[Pal/Linux-SGX] DONTMERGE: Initial EDMM dynamic heap implementation #2190
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Reviewed 13 of 13 files at r1.
Reviewable status: all files reviewed, 3 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @vijaydhanraj)
Pal/src/host/Linux-SGX/enclave_pages.c, line 313 at r1 (raw file):
out: _DkInternalUnlock(&g_heap_vma_lock); if (g_pal_sec.edmm_enable_heap && new_allocation && ret) {
new_ allocation doesn’t seem correct when addr is specified.
when addr isn’t specified, it’s size.
Pal/src/host/Linux-SGX/enclave_pages.c, line 401 at r1 (raw file):
_DkInternalUnlock(&g_heap_vma_lock); if (ret >=0 && g_pal_sec.edmm_enable_heap) { if (free_edmm_page_range(addr, size) < 0)
This doesn’t seem correct as the region can be scattered.
or is it idenpotent?
Pal/src/host/Linux-SGX/sgx_main.c, line 460 at r1 (raw file):
/* skip adding free (heap) pages to the enclave */ if (enclave->pal_sec.edmm_enable_heap && !strcmp(areas[i].desc, "free")) { goto skip_add;
Please don’t use unnecessary goto. just negate if condition.
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Reviewed 13 of 13 files at r1.
Reviewable status: all files reviewed, 48 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @vijaydhanraj and @yamahata)
a discussion (no related file):
It looks like we have a big problem with multi-threading here... I actually don't know how to enable EDMM correctly in case of multi-threaded memory allocations. @vijaydhanraj Could you research this area a bit? Surely other memory allocators found good way of dealing with it.
I can imagine two ways:
- Each thread has its own sub-region of enclave memory. Looks brittle (we don't have too much enclave memory).
- All threads issue requests to some helper thread that performs all allocations (I think that's what SGX driver does). But this leads to a problem of a new helper thread...
Looks like a tough problem to solve.
Documentation/manifest-syntax.rst, line 379 at r1 (raw file):
This syntax enables EDMM dynamic heap feature available as part of Intel SGX2 capable hardware. By default the feature is disabled but when enabled, EPC
No reason to state again that the feature is disabled by default. Simply remove this part and start with When enabled, EPC....
Documentation/manifest-syntax.rst, line 380 at r1 (raw file):
This syntax enables EDMM dynamic heap feature available as part of Intel SGX2 capable hardware. By default the feature is disabled but when enabled, EPC pages are not added when creating the enclave but allocated when an unavailable
unavailable sounds weird. Maybe allocated dynamically using EACCEPT when Graphene requests more heap memory. The EACCEPT triggers....
Documentation/manifest-syntax.rst, line 382 at r1 (raw file):
pages are not added when creating the enclave but allocated when an unavailable page is EACCEPT'ed. This triggers a page fault (#PF) which is handled by the Intel SGX driver (legacy driver) which EAUG's the page and is then EACCEPT'ed
...which EAUG's the page and returns the control back to the in-Graphene enclave,
which in turn continues from the same EACCEPT instruction (but this time this
instruction succeeds). This does help...
Documentation/manifest-syntax.rst, line 383 at r1 (raw file):
page is EACCEPT'ed. This triggers a page fault (#PF) which is handled by the Intel SGX driver (legacy driver) which EAUG's the page and is then EACCEPT'ed by the enclave. This does help reduce the loading time of a large enclave
help to reduce
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 14 at r1 (raw file):
#include "sgx_attest.h" #include "gsgx.h"
Please remove this include from everywhere. See my other comment below on this.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 121 at r1 (raw file):
const sgx_quote_nonce_t* nonce, char** quote, size_t* quote_len); int ocall_trim_epc_pages(struct sgx_range* rg);
What is struct sgx_range? I guess it is defined in sgx.h of the legacy OOT driver?
I don't like the idea of using gsgx.h (that embeds sgx.h) for this. Could you copy-paste this struct inside sgx_arch.h (or some similar SGX-specific header in Graphene) and use this header?
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 121 at r1 (raw file):
const sgx_quote_nonce_t* nonce, char** quote, size_t* quote_len); int ocall_trim_epc_pages(struct sgx_range* rg);
Also, what is rg? Let's use a proper name for it, e.g., enclave_pages_range or epc_pages_range.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 123 at r1 (raw file):
int ocall_trim_epc_pages(struct sgx_range* rg); int ocall_notify_accept(struct sgx_range* rg);
Please add a newline here.
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1708 at r1 (raw file):
int ocall_trim_epc_pages(struct sgx_range* rg) { int retval = 0; struct sgx_range* ms;
I am a bit torn here. Re-using struct sgx_range is a smart optimization, but I would still prefer to follow our convention in this file to declare OCALL-specific structs. So please add a new struct ms_ocall_sgx_range_t (with the same fields as sgx_range) and use it here internally.
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1710 at r1 (raw file):
struct sgx_range* ms; void *old_ustack = sgx_prepare_ustack();
* is wrongly aligned
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1730 at r1 (raw file):
int ocall_notify_accept(struct sgx_range* rg) { int retval = 0; struct sgx_range* ms;
ditto
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1732 at r1 (raw file):
struct sgx_range* ms; void *old_ustack = sgx_prepare_ustack();
ditto
Pal/src/host/Linux-SGX/enclave_pages.c, line 10 at r1 (raw file):
#include "pal_security.h" #include "gsgx.h"
remove
Pal/src/host/Linux-SGX/enclave_pages.c, line 86 at r1 (raw file):
} #define SE_DECLSPEC_ALIGN(x) __attribute__((aligned(x)))
You seem to need this because EACCEPT requires proper (64B) alignment. But I don't like that you're declaring a macro here. Let's just re-use already defined __sgx_mem_aligned (512 alignment). It's a bit of an overkill, but it's a more readable approach. And we use it everywhere else (see e.g. enclave_platform.c).
Pal/src/host/Linux-SGX/enclave_pages.c, line 87 at r1 (raw file):
#define SE_DECLSPEC_ALIGN(x) __attribute__((aligned(x))) static int free_edmm_page_range(void *start, size_t size)
Please add some comments to this function describing the flows. You can even draw an ASCII diagram if you want to :)
Pal/src/host/Linux-SGX/enclave_pages.c, line 88 at r1 (raw file):
#define SE_DECLSPEC_ALIGN(x) __attribute__((aligned(x))) static int free_edmm_page_range(void *start, size_t size) {
Please move to previous line
Pal/src/host/Linux-SGX/enclave_pages.c, line 89 at r1 (raw file):
static int free_edmm_page_range(void *start, size_t size) { void *addr = (void *)((uintptr_t)start & (~(PRESET_PAGESIZE-1)));
void *addr -> void* addr
(void *) -> (void*)
We have a special macro to align to the beginning of page: ALLOC_ALIGN_DOWN_PTR
Pal/src/host/Linux-SGX/enclave_pages.c, line 90 at r1 (raw file):
{ void *addr = (void *)((uintptr_t)start & (~(PRESET_PAGESIZE-1))); void *end = addr + size;
Here and everywhere: fix alignment of *
Pal/src/host/Linux-SGX/enclave_pages.c, line 99 at r1 (raw file):
memset(&si.reserved, 0, sizeof(si.reserved)); rg.start_addr = (unsigned long) addr;
No space between case and variable
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
rg.start_addr = (unsigned long) addr; rg.nr_pages = size / PRESET_PAGESIZE;
Please don't use PRESET_PAGESIZE. We should use g_pal_state.alloc_align.
Pal/src/host/Linux-SGX/enclave_pages.c, line 102 at r1 (raw file):
rg.nr_pages = size / PRESET_PAGESIZE; ret = ocall_trim_epc_pages(&rg); if (ret) {
Please replace all such occurrences with ret < 0
Pal/src/host/Linux-SGX/enclave_pages.c, line 104 at r1 (raw file):
if (ret) { log_debug("EPC trim page on [%p, %p) failed (%d)\n", addr, end, ret); return -1;
Why -1? Simply return ret;
Pal/src/host/Linux-SGX/enclave_pages.c, line 111 at r1 (raw file):
if (ret) { log_debug("EDMM accept page failed while trimming: %p %d\n", (void *)addr, ret); return -1;
Why -1? Simply return ret;
Pal/src/host/Linux-SGX/enclave_pages.c, line 118 at r1 (raw file):
if (ret) { log_debug("EPC notify_accept on [%p, %p) failed (%d)\n", addr, end, ret); return -1;
Why -1? Simply return ret;
Pal/src/host/Linux-SGX/enclave_pages.c, line 125 at r1 (raw file):
static int get_edmm_page_range(void *start, size_t size, bool executable) {
ditto
Pal/src/host/Linux-SGX/enclave_pages.c, line 130 at r1 (raw file):
log_debug("%s: start = %lx, size = %lx, is_executable = %s\n", __func__, start, size, (executable) ? "TRUE" : "FALSE"); SE_DECLSPEC_ALIGN(sizeof(sgx_arch_sec_info_t)) sgx_arch_sec_info_t si;
ditto
Pal/src/host/Linux-SGX/enclave_pages.c, line 136 at r1 (raw file):
memset(&si.reserved, 0, sizeof(si.reserved)); SE_DECLSPEC_ALIGN(sizeof(sgx_arch_sec_info_t)) sgx_arch_sec_info_t smi = si;
Please add a comment explaining why you need both si and smi.
Pal/src/host/Linux-SGX/enclave_pages.c, line 146 at r1 (raw file):
if (ret) { log_debug("EDMM accept page failed: %p %d\n", (void *)addr, ret); return -1;
return ret
Pal/src/host/Linux-SGX/enclave_pages.c, line 149 at r1 (raw file):
} /* EMODPE doesn't return any value */
This comment alone is not enough to understand what you're doing. Please expand.
Pal/src/host/Linux-SGX/enclave_pages.c, line 246 at r1 (raw file):
assert(vma->top - vma->bottom >= (ptrdiff_t)freed); size_t allocated = vma->top - vma->bottom - freed; *new_allocation = allocated;
You seem to be using new_allocation as boolean, why did you declare it as size_t? Please make it boolean. Also, maybe add a comment why this variable is needed?
Pal/src/host/Linux-SGX/enclave_pages.c, line 313 at r1 (raw file):
out: _DkInternalUnlock(&g_heap_vma_lock); if (g_pal_sec.edmm_enable_heap && new_allocation && ret) {
Please make ret more explicit: ret != NULL (otherwise I thought initially that ret means "error code").
Pal/src/host/Linux-SGX/enclave_pages.c, line 313 at r1 (raw file):
out: _DkInternalUnlock(&g_heap_vma_lock); if (g_pal_sec.edmm_enable_heap && new_allocation && ret) {
Can you actually do it outside of the lock? Isn't it possible that while you're here, some other enclave thread decided to free this memory region, and you have a data race?
We need to think how to fix this multi-threading issue. I don't want to simply move this new logic under the g_heap_vma_lock because this logic goes out-and-in the enclave, so everything will become extremely slow. I can't come up with something good right now. Maybe @yamahata and @boryspoplawski and @mkow ?
Pal/src/host/Linux-SGX/enclave_pages.c, line 314 at r1 (raw file):
_DkInternalUnlock(&g_heap_vma_lock); if (g_pal_sec.edmm_enable_heap && new_allocation && ret) { if (get_edmm_page_range(ret, size, 1) < 0)
I think this is wrong. It is possible that the [ret, size) memory region was partly allocated before. So you'll end up with EACCEPT on the same page. Or am I wrong?
Pal/src/host/Linux-SGX/enclave_pages.c, line 315 at r1 (raw file):
if (g_pal_sec.edmm_enable_heap && new_allocation && ret) { if (get_edmm_page_range(ret, size, 1) < 0) ret = NULL;
Please add some comments. Also, could you end up in "half-allocated" state here?
Pal/src/host/Linux-SGX/enclave_pages.c, line 401 at r1 (raw file):
Previously, yamahata wrote…
This doesn’t seem correct as the region can be scattered.
or is it idenpotent?
Isaku is right. This is not correct.
Pal/src/host/Linux-SGX/pal_security.h, line 22 at r1 (raw file):
sgx_measurement_t mr_signer; sgx_attributes_t enclave_attributes; bool edmm_enable_heap;
Please move after heap_min, heap_max.
Pal/src/host/Linux-SGX/sgx_enclave.c, line 31 at r1 (raw file):
#include "sigset.h" #include "gsgx.h"
Please remove this (and declare all the needed constants in sgx_arch.h or smth)
Pal/src/host/Linux-SGX/sgx_enclave.c, line 686 at r1 (raw file):
} extern int g_isgx_device;
Please move inside the function, right before the statement where you use it.
Pal/src/host/Linux-SGX/sgx_enclave.c, line 688 at r1 (raw file):
extern int g_isgx_device; static long sgx_ocall_trim_epc_pages(void *pms) { struct sgx_range *rg = (struct sgx_range *)pms;
All * alignments are wrong here :)
Pal/src/host/Linux-SGX/sgx_enclave.c, line 689 at r1 (raw file):
static long sgx_ocall_trim_epc_pages(void *pms) { struct sgx_range *rg = (struct sgx_range *)pms; ODEBUG(OCALL_EVENTFD, rg);
EVENTFD?
Pal/src/host/Linux-SGX/sgx_enclave.c, line 696 at r1 (raw file):
static long sgx_ocall_notify_accept(void *pms) { struct sgx_range *rg = (struct sgx_range *)pms; ODEBUG(OCALL_EVENTFD, rg);
EVENTFD?
Pal/src/host/Linux-SGX/sgx_framework.c, line 141 at r1 (raw file):
} #endif
Please keep this empty line
python/graphenelibos/sgx_sign.py, line 594 at r1 (raw file):
desc, flags) else: if edmm_enable_heap == 1 and (area.desc == "free"):
No need for parenthesis
python/graphenelibos/sgx_sign.py, line 595 at r1 (raw file):
else: if edmm_enable_heap == 1 and (area.desc == "free"): continue
Please add a comment that you want to skip EADDing of heap ("free") pages when EDMM is enabled.
python/graphenelibos/sgx_sign.py, line 766 at r1 (raw file):
print(' misc_select: %08x' % int.from_bytes(attr['misc_select'], byteorder='big')) print(' date: %d-%02d-%02d' % (attr['year'], attr['month'], attr['day'])) print(" edmm_heap: %d" % (attr['edmm_enable_heap']))
Please use the same name edmm_enable_heap, to avoid confusion (and add more spaces everywhere here, for correct indentation)
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @vijaydhanraj, and @yamahata)
a discussion (no related file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
It looks like we have a big problem with multi-threading here... I actually don't know how to enable EDMM correctly in case of multi-threaded memory allocations. @vijaydhanraj Could you research this area a bit? Surely other memory allocators found good way of dealing with it.
I can imagine two ways:
- Each thread has its own sub-region of enclave memory. Looks brittle (we don't have too much enclave memory).
- All threads issue requests to some helper thread that performs all allocations (I think that's what SGX driver does). But this leads to a problem of a new helper thread...
Looks like a tough problem to solve.
I didn't read all the code yet, but I think I get the issue (if not, please correct me).
The first solution doesn't scale, I don't think it's acceptable.
The second sounds a bit PITA.
What about having a global (thread safe) "registry" of pages which have pending EDMM changes? If a thread would want to modify something which is already waiting for a modification issued by another thread then it would need to wait on this registry and continue once this particular page is changeable again.
Documentation/manifest-syntax.rst, line 379 at r1 (raw file):
Intel SGX2 capable hardware
Please link to sgx-intro.html#term-sgx2.
Documentation/manifest-syntax.rst, line 381 at r1 (raw file):
capable hardware. By default the feature is disabled but when enabled, EPC pages are not added when creating the enclave but allocated when an unavailable page is EACCEPT'ed. This triggers a page fault (#PF) which is handled by the
EACCEPT'ed -> EACCEPTed or EACCEPT-ed (ditto for other places)
Documentation/manifest-syntax.rst, line 385 at r1 (raw file):
This does help reduce the loading time of a large enclave application but [...]
I think the biggest advantage of EDMM is that you pay the price only for the pages you actually used. So, you can say e.g. that your enclave will have 128 GB, even if you won't use most of it, i.e. you don't have to tailor the size precisely for each workload.
Pal/src/host/Linux-SGX/enclave_pages.c, line 136 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add a comment explaining why you need both
siandsmi.
Actually, what this smi name means? Maybe you could use a bit longer, more descriptive names?
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @vijaydhanraj, and @yamahata)
a discussion (no related file):
What about having a global (thread safe) "registry" of pages which have pending EDMM changes? If a thread would want to modify something which is already waiting for a modification issued by another thread then it would need to wait on this registry and continue once this particular page is changeable again.
This sounds like we'll need futexes inside the enclave's memory allocator (in enclave_pages.c)? Looks like a PITA itself. Also, why would this be better than simply moving the EACCEPT logic under the g_heap_vma_lock global spinlock? (Rather than spinlock vs futex argument, but futexes in the enclave is also a bad idea).
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Documentation/manifest-syntax.rst, line 385 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
This does help reduce the loading time of a large enclave application but [...]I think the biggest advantage of EDMM is that you pay the price only for the pages you actually used. So, you can say e.g. that your enclave will have 128 GB, even if you won't use most of it, i.e. you don't have to tailor the size precisely for each workload.
Agree with Michal, we should also highlight this.
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
a discussion (no related file):
sounds like we'll need futexes inside the enclave's memory allocator (in
enclave_pages.c)?
Why is this a problem? Our memory management requires locks anyways.
Also, why would this be better than simply moving the EACCEPT logic under the g_heap_vma_lock global spinlock? (Rather than spinlock vs futex argument, but futexes in the enclave is also a bad idea).
Sounds like a potential bottleneck for a case where a lot of threads are allocating memory?
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
a discussion (no related file):
Why is this a problem? Our memory management requires locks anyways.
We currently use spinlocks everywhere in the lowest level of trusted PAL. The only place where futexes are used is the Exitless feature. My point is that I'm not sure our code is ready for futexes, and it will be pretty complex to implement correctly and catch all the segfault bugs due to data races. But I don't know, probably there is no other way but futexes.
Sounds like a potential bottleneck for a case where a lot of threads are allocating memory?
Yes, this could be a perf issue. On the other hand, the current implementation of EDMM is already slow as hell. And I don't think that real-world applications (and memory managers) frequently do this "a lot of threads allocating memory" pattern. My assumption would be that apps typically pre-allocate a bunch of memory regions (one for each thread), and then draw from this pre-allocated pool.
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
a discussion (no related file):
My assumption would be that apps typically pre-allocate a bunch of memory regions (one for each thread)
Yeah, but don't they do this at the same time, usually?
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Reviewable status: all files reviewed, 51 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, and @yamahata)
a discussion (no related file):
Previously, mkow (Michał Kowalczyk) wrote…
My assumption would be that apps typically pre-allocate a bunch of memory regions (one for each thread)
Yeah, but don't they do this at the same time, usually?
For initial analysis, I have moved the EACCEPT and EREMOVE logic under the g_heap_vma_lock lock temporarily. Looking into other memory allocator designs and will address this issue before the actual PR
Documentation/manifest-syntax.rst, line 379 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
No reason to state again that the feature is disabled by default. Simply remove this part and start with
When enabled, EPC....
Done.
Documentation/manifest-syntax.rst, line 379 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Intel SGX2 capable hardwarePlease link to sgx-intro.html#term-sgx2.
Done.
Documentation/manifest-syntax.rst, line 380 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
unavailablesounds weird. Maybeallocated dynamically using EACCEPT when Graphene requests more heap memory. The EACCEPT triggers....
Done.
Documentation/manifest-syntax.rst, line 381 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
EACCEPT'ed->EACCEPTedorEACCEPT-ed(ditto for other places)
Reworded so this doesn't apply anymore but will follow the convention when using at other places.
Documentation/manifest-syntax.rst, line 382 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
...which EAUG's the page and returns the control back to the in-Graphene enclave, which in turn continues from the same EACCEPT instruction (but this time this instruction succeeds). This does help...
Done, just removed in-Graphene as we simply use enclave elsewhere in the text.
Documentation/manifest-syntax.rst, line 383 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
help to reduce
Done.
Documentation/manifest-syntax.rst, line 385 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Agree with Michal, we should also highlight this.
yes added this info as well.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 14 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please remove this include from everywhere. See my other comment below on this.
Yes removed from enclave_ocalls.h and enclave_pages.c but need need this header file in sgx_enclave.c as we call the trim/notify_accept IOCTLs here.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 121 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
What is
struct sgx_range? I guess it is defined insgx.hof the legacy OOT driver?I don't like the idea of using
gsgx.h(that embedssgx.h) for this. Could you copy-paste this struct insidesgx_arch.h(or some similar SGX-specific header in Graphene) and use this header?
struct sgx_range is a sgx2 specific struct to provide a range of addresses to trim/remove. Yes, this is defined in sgx_user.h struct of the legacy OOT driver.
Based on @dimakuv's comment, I have created an OCALL-specific struct ms_ocall_sgx_range_twhich removes the need to duplicate struct sgx_range and also can remove the gsgx.h file.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 121 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Also, what is
rg? Let's use a proper name for it, e.g.,enclave_pages_rangeorepc_pages_range.
rg was short for range. But this is removed after introducing OCALL-specific struct ms_ocall_sgx_range_t
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 123 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add a newline here.
Done.
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1708 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
I am a bit torn here. Re-using
struct sgx_rangeis a smart optimization, but I would still prefer to follow our convention in this file to declare OCALL-specific structs. So please add a new structms_ocall_sgx_range_t(with the same fields assgx_range) and use it here internally.
yes, added OCALL-specific struct ms_ocall_sgx_range_t
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1710 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
*is wrongly aligned
Done.
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1730 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
ditto
Done.
Pal/src/host/Linux-SGX/enclave_ocalls.c, line 1732 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
ditto
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 10 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
remove
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 86 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
You seem to need this because EACCEPT requires proper (64B) alignment. But I don't like that you're declaring a macro here. Let's just re-use already defined
__sgx_mem_aligned(512 alignment). It's a bit of an overkill, but it's a more readable approach. And we use it everywhere else (see e.g.enclave_platform.c).
Removed #define SE_DECLSPEC_ALIGN(x) __attribute__((aligned(x))) and used __sgx_mem_aligned. But why do we want to use a 512B alignment when 64B is the requirement?
Pal/src/host/Linux-SGX/enclave_pages.c, line 87 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add some comments to this function describing the flows. You can even draw an ASCII diagram if you want to :)
Added a detailed explanation of the function.
Pal/src/host/Linux-SGX/enclave_pages.c, line 88 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please move to previous line
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 89 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
void *addr->void* addr
(void *)->(void*)We have a special macro to align to the beginning of page:
ALLOC_ALIGN_DOWN_PTR
Thanks, used this macro and also took care of the * misalignment.
Pal/src/host/Linux-SGX/enclave_pages.c, line 90 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Here and everywhere: fix alignment of
*
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 99 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
No space between case and variable
This code is removed but will keep an eye out for other typecasting variables.
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please don't use
PRESET_PAGESIZE. We should useg_pal_state.alloc_align.
Done, but this name g_pal_state.alloc_align is a little unclear.
Pal/src/host/Linux-SGX/enclave_pages.c, line 102 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please replace all such occurrences with
ret < 0
That will not be correct as sgx_accept returns a positive value as an error code. For example, it can return SGX_PAGE_ATTRIBUTES_MISMATCH which is 19. So unified all returns to -1.
But now I have just changed ocall_* functions to return the value returned and check for ret < 0
Pal/src/host/Linux-SGX/enclave_pages.c, line 104 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why
-1? Simplyreturn ret;
please refer to the earlier comment.
Pal/src/host/Linux-SGX/enclave_pages.c, line 111 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why
-1? Simplyreturn ret;
ditto
Pal/src/host/Linux-SGX/enclave_pages.c, line 118 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why
-1? Simplyreturn ret;
ditto
Pal/src/host/Linux-SGX/enclave_pages.c, line 125 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
ditto
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 130 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
ditto
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 136 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Actually, what this
sminame means? Maybe you could use a bit longer, more descriptive names?
Renamed si and smi to secinfo and secinfo_extend. Original intention was si meant secinfo struct and smi meant secinfo modified/extended :)
using two variables as we don't want to add SGX_SECINFO_FLAGS_X and clear it in the next iteration for sgx_accept. Do we want a comment here for this? I have added comments explaining other things which will make these declarations clear.
Pal/src/host/Linux-SGX/enclave_pages.c, line 146 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
return ret
return from sgx_accept is a positive number, so setting this explicitly to -1
Pal/src/host/Linux-SGX/enclave_pages.c, line 149 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
This comment alone is not enough to understand what you're doing. Please expand.
yes, have explained in detail. Hope this helps.
Pal/src/host/Linux-SGX/enclave_pages.c, line 246 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
You seem to be using
new_allocationas boolean, why did you declare it assize_t? Please make it boolean. Also, maybe add a comment why this variable is needed?
The logic around new_allocation is modified to take into account free spaces while between VMAs while merging vma_above. Now this variable is not used.
But I have added comments here for the new logic.
Pal/src/host/Linux-SGX/enclave_pages.c, line 313 at r1 (raw file):
Previously, yamahata wrote…
new_ allocation doesn’t seem correct when addr is specified.
when addr isn’t specified, it’s size.
@yamahata the logic around new_allocation is modified to take into account free spaces between VMAs while merging vma_above. Please take a look and see if this addresses your concern.
Pal/src/host/Linux-SGX/enclave_pages.c, line 313 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please make
retmore explicit:ret != NULL(otherwise I thought initially that ret means "error code").
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 313 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Can you actually do it outside of the lock? Isn't it possible that while you're here, some other enclave thread decided to free this memory region, and you have a data race?
We need to think how to fix this multi-threading issue. I don't want to simply move this new logic under the
g_heap_vma_lockbecause this logic goes out-and-in the enclave, so everything will become extremely slow. I can't come up with something good right now. Maybe @yamahata and @boryspoplawski and @mkow ?
yes, I have moved the allocation and deallocation inside the g_heap_vma_lock temporarily. Looking at other memory allocator designs to see how to address the bottleneck for multi-threaded scenarios.
Pal/src/host/Linux-SGX/enclave_pages.c, line 314 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
I think this is wrong. It is possible that the
[ret, size)memory region was partly allocated before. So you'll end up with EACCEPT on the same page. Or am I wrong?
yes pls see the earlier comment.
Pal/src/host/Linux-SGX/enclave_pages.c, line 315 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add some comments. Also, could you end up in "half-allocated" state here?
yes, this could happen when we new addr + size space multiple VMAs having free spaces between them. I have addressed this by tracking free spaces between VMAs while walking the g_heap_vma_list and only call EACCEPT on those ranges.
Pal/src/host/Linux-SGX/enclave_pages.c, line 401 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Isaku is right. This is not correct.
At least on my test runs with entire LibOS regression tests, I didn't encounter non-continuous regions but I have implemented a simple logic that tracks the free ranges while parsing the VMAs and frees them.
Pal/src/host/Linux-SGX/pal_security.h, line 22 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please move after
heap_min, heap_max.
Done
Pal/src/host/Linux-SGX/sgx_enclave.c, line 31 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please remove this (and declare all the needed constants in
sgx_arch.hor smth)
Moving this to sgx_arch.h is little tricky because of redeclaration conflicts that arise from pal\src\host\Linux-SGX\generated-offsets.c file. Here we have both sgx_*.h files as part of pal_linux.h as well as gsgx.h.
The reason we have it here is because of IOCTL calls to the sgx driver very similar to how we have this header in sgx_framework.c
Pal/src/host/Linux-SGX/sgx_enclave.c, line 686 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please move inside the function, right before the statement where you use it.
Done.
Pal/src/host/Linux-SGX/sgx_enclave.c, line 688 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
All
*alignments are wrong here :)
Done.
Pal/src/host/Linux-SGX/sgx_enclave.c, line 689 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
EVENTFD?
Copy-paste error, fixed it.
Pal/src/host/Linux-SGX/sgx_enclave.c, line 696 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
EVENTFD?
Done.
Pal/src/host/Linux-SGX/sgx_framework.c, line 141 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please keep this empty line
Done.
Pal/src/host/Linux-SGX/sgx_main.c, line 460 at r1 (raw file):
Previously, yamahata wrote…
Please don’t use unnecessary goto. just negate if condition.
Not sure but I don't think a simple negation would work here as we only need to skip adding pages only when EDMM is active and the pages are free. But I have removed goto by using an if and else statement.
python/graphenelibos/sgx_sign.py, line 594 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
No need for parenthesis
Done.
python/graphenelibos/sgx_sign.py, line 595 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add a comment that you want to skip EADDing of heap (
"free") pages when EDMM is enabled.
Done.
python/graphenelibos/sgx_sign.py, line 766 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please use the same name
edmm_enable_heap, to avoid confusion (and add more spaces everywhere here, for correct indentation)
Done.
There was a problem hiding this comment.
Reviewed 13 of 13 files at r2.
Reviewable status: all files reviewed, 43 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @mkow, @vijaydhanraj, and @yamahata)
a discussion (no related file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
For initial analysis, I have moved the
EACCEPTandEREMOVElogic under theg_heap_vma_locklock temporarily. Looking into other memory allocator designs and will address this issue before the actual PR
Sounds good, Vijay!
a discussion (no related file):
default default signal handler.
Typo in the commit message (two times default)
LibOS/shim/test/regression/mmap_file.c, line 1 at r2 (raw file):
#define _GNU_SOURCE
Borys would love this test :) I think we should rewrite this whole file (or burn it).
LibOS/shim/test/regression/test_libos.py, line 402 at r2 (raw file):
'On SGX, SIGBUS isn\'t always implemented correctly, for lack ' 'of memory protection. For now, some of these cases won\'t work.') def test_051_mmap_sgx(self):
The name is weird now: you have _sgx in the name, but it is actually skipped on SGX. So maybe just keep the old name, _mmap?
Pal/src/host/Linux-SGX/db_main.c, line 713 at r2 (raw file):
ocall_exit(1, true); } if (!g_pal_sec.edmm_enable_heap && preheat_enclave == 1) {
This is a good catch, but I would also print a log_warning in this case. Something like:
if (g_pal_sec.edmm_enable_heap && preheat_enclave) {
log_warning("EDMM ('sgx.edmm_enable_heap') and preheat-enclave ('sgx.preheat_enclave') are both enabled"
" but they cannot be combined. Graphene will use EDMM and disable preheat-enclave now.");
}
Something like this...
Pal/src/host/Linux-SGX/enclave_pages.c, line 86 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Removed
#define SE_DECLSPEC_ALIGN(x) __attribute__((aligned(x)))and used__sgx_mem_aligned. But why do we want to use a512Balignment when64Bis the requirement?
For simplicity. But sure, you can add a new macro __sgx_64byte_aligned or something like this. Feel free to add it if you feel this is important.
I just didn't like the declaration of the macro in this file.
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Done, but this name
g_pal_state.alloc_alignis a little unclear.
@mkow knows better why we have such a name. I think this has to do something with Windows.
Pal/src/host/Linux-SGX/enclave_pages.c, line 102 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
That will not be correct as sgx_accept returns a positive value as an error code. For example, it can return
SGX_PAGE_ATTRIBUTES_MISMATCHwhich is19. So unified all returns to-1.But now I have just changed
ocall_*functions to return the value returned and check forret < 0
Thanks. I didn't realize that.
Pal/src/host/Linux-SGX/enclave_pages.c, line 136 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Renamed
siandsmitosecinfoandsecinfo_extend. Original intention wassi meant secinfo structandsmi meant secinfo modified/extended:)using two variables as we don't want to add
SGX_SECINFO_FLAGS_Xand clear it in the next iteration forsgx_accept. Do we want a comment here for this? I have added comments explaining other things which will make these declarations clear.
Thanks, I think everything is clear now.
Pal/src/host/Linux-SGX/enclave_pages.c, line 91 at r2 (raw file):
} /* This function trims an EPC page on enclave's request. The sequence is as below,
Why do you say an EPC page? You can submit several pages here. Please fix the description.
Pal/src/host/Linux-SGX/enclave_pages.c, line 93 at r2 (raw file):
/* This function trims an EPC page on enclave's request. The sequence is as below, * 1. Enclave calls SGX driver IOCTL to change the page's type to PT_TRIM. * 2. In turn driver invokes ETRACK to track page's address on all processors and issues IPI to flush
In turn is not needed here, just remove it.
Also, I would prefer to replace processors with CPUs
Pal/src/host/Linux-SGX/enclave_pages.c, line 96 at r2 (raw file):
* stale TLB entries. * 3. Enclave issues an EACCEPT to accept changes to the EPC page. * 4. Notifies the driver to remove EPC page which issues EREMOVE inst to complete the request. */
Enclave notifies...
Pal/src/host/Linux-SGX/enclave_pages.c, line 96 at r2 (raw file):
* stale TLB entries. * 3. Enclave issues an EACCEPT to accept changes to the EPC page. * 4. Notifies the driver to remove EPC page which issues EREMOVE inst to complete the request. */
I would separate driver's EREMOVE in a separate item:
4. Enclave notifies the driver to remove the EPC page (using an IOCTL).
5. Driver issues EREMOVE to complete the request (maybe lazily).
Pal/src/host/Linux-SGX/enclave_pages.c, line 107 at r2 (raw file):
memset(&secinfo.reserved, 0, sizeof(secinfo.reserved)); unsigned int nr_pages = size / g_pal_state.alloc_align;
Do we guarantee that size is a multiple of alloc_align? For example, could this function receive size = 8? Then we'll have nr_pages = 0 and the logic breaks...
I'm fine with an assert(size % g_pal_state.alloc_align == 0). But maybe you want to ALLOC_ALIGN_UP(size). I don't know which one is a better fit here.
Pal/src/host/Linux-SGX/enclave_pages.c, line 114 at r2 (raw file):
} for (void* page_addr = addr; page_addr < end; page_addr += g_pal_state.alloc_align) {
void* -> char* (it is technically disallowed to do pointer arithmetic on void* so we should always use char* for "modifiable" pointers)
Pal/src/host/Linux-SGX/enclave_pages.c, line 124 at r2 (raw file):
ret = ocall_notify_accept(addr, nr_pages); if (ret < 0) { log_debug("EPC notify_accept on [%p, %p), %d pages failed (%d)\n", addr, end, nr_pages, ret);
Please unify the message format -- in trim_epc_pages above you don't have this %d pages.
Pal/src/host/Linux-SGX/enclave_pages.c, line 131 at r2 (raw file):
} /* This function allocates a new page at an address in ELRANGE of an enclave. If the page contains
Why a new page? We may submit several pages to this function. Please fix the description.
Pal/src/host/Linux-SGX/enclave_pages.c, line 133 at r2 (raw file):
/* This function allocates a new page at an address in ELRANGE of an enclave. If the page contains * executable code, the page permissions are extended once the page is in a valid state. The * allocation sequence is described below
Add : at the end
Pal/src/host/Linux-SGX/enclave_pages.c, line 134 at r2 (raw file):
* executable code, the page permissions are extended once the page is in a valid state. The * allocation sequence is described below * 1. Enclave invokes EACCEPT on the new page request which triggers a page fault(#PF) as the page
page fault(#PF) -> page fault (#PF)
Pal/src/host/Linux-SGX/enclave_pages.c, line 136 at r2 (raw file):
* 1. Enclave invokes EACCEPT on the new page request which triggers a page fault(#PF) as the page * is not available yet. * 2. Driver catches this #PF and issues EAUG for the page. The control returns back to enclave.
EAUG for the page (at this point the page becomes VALID and may be used by the enclave).
Pal/src/host/Linux-SGX/enclave_pages.c, line 140 at r2 (raw file):
static int get_edmm_page_range(void* start, size_t size, bool executable) { uintptr_t lo = (uintptr_t)start; uintptr_t addr = lo + size;
Do we guarantee that size is a multiple of alloc_align? For example, could this function receive size = 8? Then we'll have weird arithmetic onaddr and the logic breaks...
I'm fine with an assert(size % g_pal_state.alloc_align == 0). But maybe you want to ALLOC_ALIGN_UP(size). I don't know which one is a better fit here.
Actually, the same for start.
Pal/src/host/Linux-SGX/enclave_pages.c, line 140 at r2 (raw file):
static int get_edmm_page_range(void* start, size_t size, bool executable) { uintptr_t lo = (uintptr_t)start; uintptr_t addr = lo + size;
Why do you use uintptr_t in this function, but you used void*/char* in the other function? I think you should use void*/char* in here.
Pal/src/host/Linux-SGX/enclave_pages.c, line 163 at r2 (raw file):
* permissions will have no effect. * Note: Page becomes valid only after EUG which will be done as part of previous sgx_accept * call. */
Given that you have a detailed explanation of the flows in the function top-comment, this feels redundant. I suggest to keep only the first sentence and remove all the rest of this comment:
/* All new pages have RW permissions initially, so after EAUG/EACCEPT, extend
* permissions of a VALID enclave page (if needed). */
Pal/src/host/Linux-SGX/enclave_pages.c, line 177 at r2 (raw file):
static void* __create_vma_and_merge(void* addr, size_t size, bool is_pal_internal, struct heap_vma* vma_above, struct edmm_heap_range* unallocated_heap) {
Please add a comment to this function that unallocated_heap is an array (of size 64 entries) that tracks the freed memory regions, and that this function updates this variable with addr, size entries.
Pal/src/host/Linux-SGX/enclave_pages.c, line 177 at r2 (raw file):
static void* __create_vma_and_merge(void* addr, size_t size, bool is_pal_internal, struct heap_vma* vma_above, struct edmm_heap_range* unallocated_heap) {
Also, the name is weird. I guess you mean something like "enclave memory regions which were not yet allocated", so maybe heap_ranges_to_alloc?
Pal/src/host/Linux-SGX/enclave_pages.c, line 240 at r2 (raw file):
* the condition `vma_below->top >= vma->bottom` */ if (g_pal_sec.edmm_enable_heap && vma_current && addr < vma_current->top) { int64_t free_size = vma_above->bottom - vma_current->top;
Why int64_t? It should be size_t. To check for overflow, just move the assert before assignment:
assert(vma_above->bottom <= vma_current->top);
size_t free_size = vma_above->bottom - vma_current->top;
Pal/src/host/Linux-SGX/enclave_pages.c, line 245 at r2 (raw file):
unallocated_heap[free_cnt].size = free_size; unallocated_heap[free_cnt].addr = vma_current->top; free_cnt++;
Please add assert(free_cnt <= EDMM_HEAP_RANGE_CNT).
Pal/src/host/Linux-SGX/enclave_pages.c, line 249 at r2 (raw file):
__func__, vma_current->top, free_size); } }
Why do you need to keep track of vma_current?
Isn't it enough to use vma_above->top and vma_above->bottom here?
Pal/src/host/Linux-SGX/enclave_pages.c, line 285 at r2 (raw file):
assert(vma->top - vma->bottom >= (ptrdiff_t)freed); size_t allocated = vma->top - vma->bottom - freed; /* No free space between VMAs found */
Is this comment correct? I think what really happens is there were some VMA merges, and this may have led to overlaps with previously-allocated pages, so these overlapping pages were marked as "freed". And you want to track those page ranges that were marked as "freed". And if there were no "freed" pages, it means that there were no overlaps (and thus no previously-allocated pages), and all VMA pages must be EACCEPTed.
Pal/src/host/Linux-SGX/enclave_pages.c, line 286 at r2 (raw file):
size_t allocated = vma->top - vma->bottom - freed; /* No free space between VMAs found */ if (g_pal_sec.edmm_enable_heap && free_cnt == 0 && allocated > 0) {
Why do you care about free_cnt and allocated? Shouldn't you only check for freed == 0?
Pal/src/host/Linux-SGX/enclave_pages.c, line 289 at r2 (raw file):
unallocated_heap[0].size = size; unallocated_heap[0].addr = addr; }
This whole logic with unallocated_heap is confusing to me. Please explain the logic, and we'll see how to do re-write it in a more readable way.
Pal/src/host/Linux-SGX/enclave_pages.c, line 304 at r2 (raw file):
void* ret = NULL; /* TODO: Should we introduce a compiler switch for EDMM? */ struct edmm_heap_range unallocated_heap[EDMM_HEAP_RANGE_CNT] = {0};
Actually, why do you want to collect the yet-not-allocated page ranges first and then perform get_edmm_page_range() on these ranges? Why not just embed get_edmm_page_range() inside __create_vma_and_merge()?
We currently perform everything under the same global lock anyway. So there won't be any difference in performance, but it will significantly simplify the existing code. And in the future, we may change that (but let's not overcomplicate it now).
Pal/src/host/Linux-SGX/enclave_pages.c, line 365 at r2 (raw file):
unallocated_heap[cnt].addr, unallocated_heap[cnt].size); if (unallocated_heap[cnt].size > 0 && get_edmm_page_range(unallocated_heap[cnt].addr, unallocated_heap[cnt].size, 1) < 0) {
Please don't do this pattern of "check and execute inside the IF statement". Extract get_edmm_page_range() on its own line.
Pal/src/host/Linux-SGX/enclave_pages.c, line 438 at r2 (raw file):
edmm_free_cnt++; } }
I suggest to embed free_edmm_page_range() directly in here, instead of tracking.
Pal/src/host/Linux-SGX/ocall_types.h, line 316 at r2 (raw file):
typedef struct { unsigned long start_addr;
Why not void*?
Pal/src/host/Linux-SGX/ocall_types.h, line 317 at r2 (raw file):
typedef struct { unsigned long start_addr; unsigned int nr_pages;
Please spaces instead of tabs.
Pal/src/host/Linux-SGX/sgx_main.c, line 458 at r2 (raw file):
} /* skip adding free (heap) pages to the enclave */
... if EDMM is enabled
Pal/src/host/Linux-SGX/sgx_main.c, line 468 at r2 (raw file):
if (areas[i].prot & PROT_EXEC) p[2] = 'X'; }
Now we have this code copy-pasted in several places. Can you extract this code in a separate func prot_flags_to_permissions_str()?
python/graphenelibos/sgx_sign.py, line 594 at r2 (raw file):
desc, flags) else: # Skip EADDing of heap("free") pages when EDMM is enabled.
heap ("free")
There was a problem hiding this comment.
Reviewed 6 of 13 files at r2.
Reviewable status: all files reviewed, 45 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @vijaydhanraj, and @yamahata)
a discussion (no related file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Sounds good, Vijay!
ack, good luck then!
Documentation/manifest-syntax.rst, line 384 at r2 (raw file):
but this time this instruction succeeds
This should sound better: "but this time the instruction succeeds"
Pal/src/host/Linux-SGX/db_main.c, line 713 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
This is a good catch, but I would also print a
log_warningin this case. Something like:if (g_pal_sec.edmm_enable_heap && preheat_enclave) { log_warning("EDMM ('sgx.edmm_enable_heap') and preheat-enclave ('sgx.preheat_enclave') are both enabled" " but they cannot be combined. Graphene will use EDMM and disable preheat-enclave now."); }Something like this...
+1, modulo alignment, in the second line " should be aligned to the previous " ;)
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 119 at r2 (raw file):
const sgx_quote_nonce_t* nonce, char** quote, size_t* quote_len); int ocall_trim_epc_pages(void* addr, unsigned int nr_pages);
should be size_t
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 121 at r2 (raw file):
int ocall_trim_epc_pages(void* addr, unsigned int nr_pages); int ocall_notify_accept(void* addr, unsigned int nr_pages);
ditto
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
@mkow knows better why we have such a name. I think this has to do something with Windows.
We're inside Linux-specific PAL, so we can't just use PAGE_SIZE I think.
Pal/src/host/Linux-SGX/enclave_pages.c, line 96 at r2 (raw file):
* stale TLB entries. * 3. Enclave issues an EACCEPT to accept changes to the EPC page. * 4. Notifies the driver to remove EPC page which issues EREMOVE inst to complete the request. */
inst
please use either insn or instr, there are many words which start with inst (e.g. "instance" or "installation")
Pal/src/host/Linux-SGX/sgx_api.h, line 57 at r2 (raw file):
* \brief Low-level wrapper around EACCEPT instruction leaf. * * Caller is responsible for parameter alignment: 64B for `si` and 4KB(page size) for `addr`.
space before (, ditto for the whole PR
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Reviewable status: all files reviewed, 46 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/db_main.c, line 713 at r2 (raw file):
ocall_exit(1, true); } if (!g_pal_sec.edmm_enable_heap && preheat_enclave == 1) {
Actually, now that I think of this, I think we should still have this option with EDMM, but slightly different - something like "sgx.preallocation_size", which would preallocate and fault a specified amount of heap at the beginning (and we could default it to e.g. 32MB), and only after you cross this amount the EDMM triggers.
What do you think? This way you could benefit from both EDMM and preheating.
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Reviewable status: all files reviewed, 45 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/db_main.c, line 713 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Actually, now that I think of this, I think we should still have this option with EDMM, but slightly different - something like "sgx.preallocation_size", which would preallocate and fault a specified amount of heap at the beginning (and we could default it to e.g. 32MB), and only after you cross this amount the EDMM triggers.
What do you think? This way you could benefit from both EDMM and preheating.
sounds good idea.
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Reviewable status: all files reviewed, 45 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
a discussion (no related file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
default default signal handler.
Typo in the commit message (two times
default)
yes fixed it.
Documentation/manifest-syntax.rst, line 384 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
but this time this instruction succeedsThis should sound better: "but this time the instruction succeeds"
Done.
LibOS/shim/test/regression/test_libos.py, line 402 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
The name is weird now: you have
_sgxin the name, but it is actually skipped on SGX. So maybe just keep the old name,_mmap?
yes agree, have removed _sgx from the test name.
Pal/src/host/Linux-SGX/db_main.c, line 713 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
+1, modulo alignment, in the second line
"should be aligned to the previous";)
Modified the message a little bit as we want to try combining both preheat_enclave as well as EDMM.
log_warning("EDMM ('sgx.edmm_enable_heap') and preheat-enclave ('sgx.preheat_enclave') are"
" both enabled. Graphene will use EDMM only for the region excluded by"
" preheat-enclave size.");
Pal/src/host/Linux-SGX/db_main.c, line 713 at r2 (raw file):
Previously, yamahata wrote…
sounds good idea.
yes, that is a good idea @mkow. I plan to try this optimization. The tricky part will be figuring out the default preheat_enclave size to balance between optimal enclave loading time and the no. of AEXs due to page faults.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 119 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
should be
size_t
SGX driver expects unsigned int for nr_pages and so I have used it. Using size_t might expand the size to 8 bytes on x64 systems.
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 121 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
ditto
pls see above.
Pal/src/host/Linux-SGX/enclave_pages.c, line 86 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
For simplicity. But sure, you can add a new macro
__sgx_64byte_alignedor something like this. Feel free to add it if you feel this is important.I just didn't like the declaration of the macro in this file.
Ok, is it fine to have the generic version #define _DECLSPEC_ALIGN(x) __attribute__((aligned(x))) in sgx_arch.h
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
We're inside Linux-specific PAL, so we can't just use
PAGE_SIZEI think.
Ok, thanks for the clarification.
Pal/src/host/Linux-SGX/enclave_pages.c, line 91 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why do you say
an EPC page? You can submit several pages here. Please fix the description.
I have reworded to trims EPC pages on enclave's request
Pal/src/host/Linux-SGX/enclave_pages.c, line 93 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
In turnis not needed here, just remove it.Also, I would prefer to replace
processorswithCPUs
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 96 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Enclave notifies...
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 96 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
I would separate driver's EREMOVE in a separate item:
4. Enclave notifies the driver to remove the EPC page (using an IOCTL). 5. Driver issues EREMOVE to complete the request (maybe lazily).
Ok, done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 96 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
inst
please use eitherinsnorinstr, there are many words which start withinst(e.g. "instance" or "installation")
I have removed inst itself here as we don't use it for other instructions. But will keep the abbreviation in mind for future usage.
Pal/src/host/Linux-SGX/enclave_pages.c, line 107 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Do we guarantee that
sizeis a multiple ofalloc_align? For example, could this function receivesize = 8? Then we'll havenr_pages = 0and the logic breaks...I'm fine with an
assert(size % g_pal_state.alloc_align == 0). But maybe you want toALLOC_ALIGN_UP(size). I don't know which one is a better fit here.
yes, it is taken care in free_enclave_pages() which calls free_edmm_page_range()
Pal/src/host/Linux-SGX/enclave_pages.c, line 114 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
void*->char*(it is technically disallowed to do pointer arithmetic onvoid*so we should always usechar*for "modifiable" pointers)
gcc didn't seem to complain but looks like other compilers like MSVC might have an issue. I now typecast to char* for arithmetic operation and then recast to void*.
Pal/src/host/Linux-SGX/enclave_pages.c, line 124 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please unify the message format -- in
trim_epc_pagesabove you don't have this%d pages.
yes have reworded the text, please let me know if this helps.
Pal/src/host/Linux-SGX/enclave_pages.c, line 131 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why
a new page? We may submit several pages to this function. Please fix the description.
Although this function takes a range (addr, size) internally we allocate at page granularity so the text. But I see your point and have reworded it.
Pal/src/host/Linux-SGX/enclave_pages.c, line 133 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Add
:at the end
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 134 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
page fault(#PF)->page fault (#PF)
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 136 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
EAUG for the page (at this point the page becomes VALID and may be used by the enclave).
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 140 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Do we guarantee that
sizeis a multiple ofalloc_align? For example, could this function receivesize = 8? Then we'll have weird arithmetic onaddrand the logic breaks...I'm fine with an
assert(size % g_pal_state.alloc_align == 0). But maybe you want toALLOC_ALIGN_UP(size). I don't know which one is a better fit here.Actually, the same for
start.
yes, both addr and size are multiple of alloc_align. This is taken care get_enclave_pages(). So arithmetic between these two variables should result in a multiple of alloc_align.
Pal/src/host/Linux-SGX/enclave_pages.c, line 140 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why do you use
uintptr_tin this function, but you usedvoid*/char*in the other function? I think you should usevoid*/char*in here.
we use uintptr_t to typecast void* in defines like ALIGN_DOWN_PTR (most defines in api.h) so was little confused and used it here. But will revert to using void*/char*
Pal/src/host/Linux-SGX/enclave_pages.c, line 163 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Given that you have a detailed explanation of the flows in the function top-comment, this feels redundant. I suggest to keep only the first sentence and remove all the rest of this comment:
/* All new pages have RW permissions initially, so after EAUG/EACCEPT, extend * permissions of a VALID enclave page (if needed). */
yes removed.
note: we only add executable permission here, no other flags are being added, so better to state as extend permission
Pal/src/host/Linux-SGX/enclave_pages.c, line 177 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Also, the name is weird. I guess you mean something like "enclave memory regions which were not yet allocated", so maybe
heap_ranges_to_alloc?
Ok, have renamed it to heap_ranges_to_alloc
Pal/src/host/Linux-SGX/enclave_pages.c, line 177 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add a comment to this function that
unallocated_heapis an array (of size 64 entries) that tracks the freed memory regions, and that this function updates this variable withaddr, sizeentries.
Isn't this explicit when reading get_enclave_pages()? This function is only called from it so not sure why a comment is needed here.
Pal/src/host/Linux-SGX/enclave_pages.c, line 240 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why
int64_t? It should besize_t. To check for overflow, just move the assert before assignment:assert(vma_above->bottom <= vma_current->top); size_t free_size = vma_above->bottom - vma_current->top;
Modified the logic a bit which removes the need for assert. Using size_t now instead of int64_t
Pal/src/host/Linux-SGX/enclave_pages.c, line 245 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please add
assert(free_cnt <= EDMM_HEAP_RANGE_CNT).
yes good point, done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 249 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why do you need to keep track of
vma_current?Isn't it enough to use
vma_above->topandvma_above->bottomhere?
No, it isn't. Let us take the below example where the request overlaps with the existing allocation.
+ +
+-----------+ top
| VMA_ABOVE_ABOVE
+---------------------+-------+ ADDR + SIZE, VMA->top
| |
+-----------+ bottom
| FREE |
+-----------+ top
| VMA_ABOVE |
| |
+-----------+ bottom
| FREE |
+-----------+ top
| |
+-----------------------------+ ADDR, VMA->bottom
| VMA_BELOW |
+-----------+ bottom
+ +
So the idea here is to identify the free spaces (unallocated regions) and only do EACCEPT on these ranges as the other ranges are already allocated. If we use vma_above->top and vma_above->bottom the free space between vma_below->top and vma_above->bottomis missed. In order to track this region, I usevma_current`.
With new changes, I have renamed vma_current to current_top and is initialized to void* current_top = (vma_below) ? MAX(vma_below->top, vma->bottom) : vma->bottom;. Before merging the vma_above I do store vma_above->top to current_top to find free space between vma_above_above and vma_above. This continues as we go upwards merging VMAs.
Pal/src/host/Linux-SGX/enclave_pages.c, line 285 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Is this comment correct? I think what really happens is
there were some VMA merges, and this may have led to overlaps with previously-allocated pages, so these overlapping pages were marked as "freed". And you want to track those page ranges that were marked as "freed". And if there were no "freed" pages, it means that there were no overlaps (and thus no previously-allocated pages), and all VMA pages must be EACCEPTed.
yes, I think. When we hit this condition, it means the allocation is somewhere after the lowest vma->bottom and heap bottom. If there were free spaces between VMAs we would have taken the vma_above path (vma_above->bottom <= vma->top)
Pal/src/host/Linux-SGX/enclave_pages.c, line 286 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why do you care about
free_cntandallocated? Shouldn't you only check forfreed == 0?
Consider the below example where the allocation request starts from a free region which also happens to be vma_below->top and ends before extending into vma_above.
+ +
| |
+----------+ top
| VMA_ABOVE|
| |
+----------+ bottom
+-----------------------------+ ADDR+SIZE, VMA->top
| FREE |
+-----------------------------+ top, ADDR, VMA->bottom
| |
| VMA_BELOW|
| |
+----------+ bottom
| |
+ +
Here if we just consider freed == 0, the if condition will fail and we miss allocating the free space, that is (addr, addr+size]. So I use allocated to check this free space and free_cnt to ensure that we don't have any other free regions which should be the case (sanity check).
Pal/src/host/Linux-SGX/enclave_pages.c, line 289 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
This whole logic with
unallocated_heapis confusing to me. Please explain the logic, and we'll see how to do re-write it in a more readable way.
I have added a detailed explanation above. Please let me know if more details are required.
Pal/src/host/Linux-SGX/enclave_pages.c, line 304 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Actually, why do you want to collect the yet-not-allocated page ranges first and then perform
get_edmm_page_range()on these ranges? Why not just embedget_edmm_page_range()inside__create_vma_and_merge()?We currently perform everything under the same global lock anyway. So there won't be any difference in performance, but it will significantly simplify the existing code. And in the future, we may change that (but let's not overcomplicate it now).
Yes we can embed get_edmm_page_range() inside __create_vma_and_merge(). I did consolidation to create a framework for EAUG batch optimization. Why do you think this is complicated? We simply pass an array and store the address ranges. The complicated part lies in identifying these free ranges.
I would prefer it this way until we finalize the EAUG batch optimization as performance won't be any different.
Pal/src/host/Linux-SGX/enclave_pages.c, line 365 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please don't do this pattern of "check and execute inside the IF statement". Extract
get_edmm_page_range()on its own line.
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 438 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
I suggest to embed
free_edmm_page_range()directly in here, instead of tracking.
free ranges can be contiguous and it is better to consolidate and just make a single free_edmm_page_range(). Please see this case, https://github.com/oscarlab/graphene/pull/2190/files#diff-c2e0a370259cd766336e18435809201836adfbe09dc2884127323a4a3e3429f8R428
Pal/src/host/Linux-SGX/ocall_types.h, line 316 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why not
void*?
Because the SGX drive IOCTL expects unsigned long and wanted to avoid unnecessary typecasting. Any issues with this or why void* would be preferred?
Pal/src/host/Linux-SGX/ocall_types.h, line 317 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please spaces instead of tabs.
oh sorry, fixed it.
Pal/src/host/Linux-SGX/sgx_api.h, line 57 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
space before
(, ditto for the whole PR
I think I have addressed all.
Pal/src/host/Linux-SGX/sgx_main.c, line 458 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
... if EDMM is enabled
I have added it but felt this was explicit.
Pal/src/host/Linux-SGX/sgx_main.c, line 468 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Now we have this code copy-pasted in several places. Can you extract this code in a separate func
prot_flags_to_permissions_str()?
yes, done.
python/graphenelibos/sgx_sign.py, line 594 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
heap ("free")
Done.
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Needed to change the commit message and along with it rebased to the latest master. Sorry about it. |
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Reviewed 1 of 13 files at r2, 5 of 11 files at r3.
Reviewable status: 10 of 16 files reviewed, 40 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" and "fixup! " found in commit messages' one-liners (waiting on @dimakuv, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_ocalls.h, line 119 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
SGX driver expects
unsigned intfornr_pagesand so I have used it. Usingsize_tmight expand the size to 8 bytes on x64 systems.
Uh, seriously? That's bad... I guess we don't have a choice then. I hope the in-kernel driver will use proper types.
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Ok, thanks for the clarification.
Oops, I meant "we can" -.-
Sorry for confusion.
Pal/src/host/Linux-SGX/enclave_pages.c, line 114 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
gccdidn't seem to complain but looks like other compilers like MSVC might have an issue. I now typecast tochar*for arithmetic operation and then recast tovoid*.
Yeah, I think it complains only with -pedantic.
Pal/src/host/Linux-SGX/ocall_types.h, line 316 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Because the SGX drive IOCTL expects
unsigned longand wanted to avoid unnecessary typecasting. Any issues with this or whyvoid*would be preferred?
I'd prefer to push such uglinesses as down as possible and keep proper types in Graphene interfaces.
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Reviewable status: 10 of 16 files reviewed, 40 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" and "fixup! " found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Oops, I meant "we can" -.-
Sorry for confusion.
It looks like PAL uses this API _DkGetAllocationAlignment() to update g_pal_state.alloc_align which inturn simply returns PRESET_PAGESIZE.
I am fine with both but if PRESET_PAGESIZE is more readable, I can change it when creating the PR.
Pal/src/host/Linux-SGX/enclave_pages.c, line 114 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Yeah, I think it complains only with
-pedantic.
got it, thanks.
Pal/src/host/Linux-SGX/ocall_types.h, line 316 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
I'd prefer to push such uglinesses as down as possible and keep proper types in Graphene interfaces.
Actually, we use this ms_ocall_sgx_range_t struct directly in the IOCTL. So if we want to avoid this, I can create a local struct that is used for the driver IOCTL and typecast payload that is part of ms_ocall_sgx_range_t. Is this preferred?
Something like below,
typedef struct {
unsigned long start_addr;
unsigned int nr_pages;
} sgx_range_t ;========> local to `static long sgx_ocall_trim_epc_pages` and `sgx_ocall_notify_accept`
typedef struct {
void* start_addr;
size_t nr_pages;
} ms_ocall_sgx_range_t ;=> used elsewhere in graphene like `ocall_trim_epc_pages` and `ocall_notify_accept`
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Reviewable status: 10 of 16 files reviewed, 39 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" and "fixup! " found in commit messages' one-liners (waiting on @dimakuv, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
It looks like
PALuses this API_DkGetAllocationAlignment()to updateg_pal_state.alloc_alignwhich inturn simply returnsPRESET_PAGESIZE.I am fine with both but if
PRESET_PAGESIZEis more readable, I can change it when creating the PR.
Tbh it's quite a mess, we need to clean this up and have only one intended way to get this value. For now whichever you prefer is fine.
Pal/src/host/Linux-SGX/ocall_types.h, line 316 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Actually, we use this
ms_ocall_sgx_range_tstruct directly in theIOCTL. So if we want to avoid this, I can create a local struct that is used for the driverIOCTLand typecast payload that is part ofms_ocall_sgx_range_t. Is this preferred?Something like below,
typedef struct { unsigned long start_addr; unsigned int nr_pages; } sgx_range_t ;========> local to `static long sgx_ocall_trim_epc_pages` and `sgx_ocall_notify_accept` typedef struct { void* start_addr; size_t nr_pages; } ms_ocall_sgx_range_t ;=> used elsewhere in graphene like `ocall_trim_epc_pages` and `ocall_notify_accept`
Yup, I prefer it this way.
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Reviewable status: 6 of 16 files reviewed, 39 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 100 at r1 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Tbh it's quite a mess, we need to clean this up and have only one intended way to get this value. For now whichever you prefer is fine.
I will leave this for now. Maybe for the final PR, we can have PRESET_PAGESIZE
Pal/src/host/Linux-SGX/ocall_types.h, line 316 at r2 (raw file):
Previously, mkow (Michał Kowalczyk) wrote…
Yup, I prefer it this way.
Done.
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Reviewed 6 of 11 files at r3, 5 of 5 files at r4.
Reviewable status: all files reviewed, 14 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
LibOS/shim/test/regression/mmap_file.c, line 1 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Borys would love this test :) I think we should rewrite this whole file (or burn it).
@boryspoplawski What do you think we should do with this file?
Pal/src/host/Linux-SGX/enclave_pages.c, line 86 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Ok, is it fine to have the generic version
#define _DECLSPEC_ALIGN(x) __attribute__((aligned(x)))insgx_arch.h
Why not just use alignas(64) here? The _DECLSPEC_ALIGN name is ugly.
Pal/src/host/Linux-SGX/enclave_pages.c, line 111 at r1 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
ditto
Shouldn't you then use -EFAULT or something similar, not just -1?
Pal/src/host/Linux-SGX/enclave_pages.c, line 304 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Yes we can embed
get_edmm_page_range()inside__create_vma_and_merge(). I did consolidation to create a framework forEAUGbatch optimization. Why do you think this is complicated? We simply pass an array and store the address ranges. The complicated part lies in identifying these free ranges.I would prefer it this way until we finalize the
EAUGbatch optimization as performance won't be any different.
OK, fair enough.
Pal/src/host/Linux-SGX/enclave_pages.c, line 365 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Done.
Not done?
Pal/src/host/Linux-SGX/ocall_types.h, line 318 at r4 (raw file):
void* start_addr; size_t nr_pages; } ms_ocall_sgx_range_t ;
Redundant space before ;
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Reviewable status: all files reviewed, 15 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
LibOS/shim/test/regression/mmap_file.c, line 1 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
@boryspoplawski What do you think we should do with this file?
I would just leave it for now, unless it's breaking in some way. We need to rewrite most of the tests anyway (especially Pal/regression)
LibOS/shim/test/regression/mmap_file.c, line 92 at r4 (raw file):
a[page_size] = 0xff; if (signal(SIGBUS, SIG_DFL) == SIG_ERR) {
Why remove it?
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Reviewable status: 14 of 16 files reviewed, 15 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
LibOS/shim/test/regression/mmap_file.c, line 92 at r4 (raw file):
Previously, boryspoplawski (Borys Popławski) wrote…
Why remove it?
Not sure why this was needed as we have already set the SIGBUS handler before accessing the end of the mapped file. I tested this both with native as well as linux-pal and it worked as expected. The only issue was with linuxSGX-pal which we have commented out as part of this PR. So removed this code.
Pal/src/host/Linux-SGX/enclave_pages.c, line 86 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why not just use
alignas(64)here? The_DECLSPEC_ALIGNname is ugly.
yes used alignas(64). This is better rather than introducing a new macro.
Pal/src/host/Linux-SGX/enclave_pages.c, line 111 at r1 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Shouldn't you then use
-EFAULTor something similar, not just -1?
yes, used -EFAULT
Pal/src/host/Linux-SGX/enclave_pages.c, line 365 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Not done?
oh my bad, I misunderstood your comment. I have separated the execution and check into different lines.
Pal/src/host/Linux-SGX/ocall_types.h, line 318 at r4 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Redundant space before
;
Done.
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Reviewable status: 14 of 16 files reviewed, 15 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
LibOS/shim/test/regression/mmap_file.c, line 92 at r4 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Not sure why this was needed as we have already set the
SIGBUShandler before accessing the end of the mapped file. I tested this both with native as well aslinux-paland it worked as expected. The only issue was withlinuxSGX-palwhich we have commented out as part of this PR. So removed this code.
It is not needed, but I don't see a reason to touch this file in this PR, especially since you disabled it in SGX tests. This would rather need a proper rewrite than removing random parts of it.
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Reviewable status: 14 of 16 files reviewed, 15 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
LibOS/shim/test/regression/mmap_file.c, line 92 at r4 (raw file):
Previously, boryspoplawski (Borys Popławski) wrote…
It is not needed, but I don't see a reason to touch this file in this PR, especially since you disabled it in SGX tests. This would rather need a proper rewrite than removing random parts of it.
Ok, I will revert the changes and just exclude the test from sgx regression test.
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Reviewed 1 of 11 files at r3, 3 of 3 files at r5.
Reviewable status: all files reviewed, 22 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 249 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
No, it isn't. Let us take the below example where the request overlaps with the existing allocation.
+ + +-----------+ top | VMA_ABOVE_ABOVE +---------------------+-------+ ADDR + SIZE, VMA->top | | +-----------+ bottom | FREE | +-----------+ top | VMA_ABOVE | | | +-----------+ bottom | FREE | +-----------+ top | | +-----------------------------+ ADDR, VMA->bottom | VMA_BELOW | +-----------+ bottom + +So the idea here is to identify the free spaces (unallocated regions) and only do
EACCEPTon these ranges as the other ranges are already allocated. If we usevma_above->topandvma_above->bottomthe free space betweenvma_below->topand vma_above->bottomis missed. In order to track this region, I usevma_current`.With new changes, I have renamed
vma_currenttocurrent_topand is initialized tovoid* current_top = (vma_below) ? MAX(vma_below->top, vma->bottom) : vma->bottom;. Before merging thevma_aboveI do storevma_above->toptocurrent_topto find free space betweenvma_above_aboveandvma_above. This continues as we go upwards merging VMAs.
Ok, thanks for explanation. I think I get it now.
I don't like the names you chose though. We have here two different concepts:
- already-existing logic of "free" memory regions: this means "already allocated but will be zeroed out" (pages exist but their data is erased)
- your newly-added logic of "unallocated" memory regions: this means "not yet allocated"
But you're using free term for both these cases. Let's separate them. I suggest to rename your new variables:
current_top->unallocated_region_addrfree_size->unallocated_region_sizefree_cnt- >heap_ranges_to_alloc_cnt
Pal/src/host/Linux-SGX/enclave_pages.c, line 285 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
yes, I think. When we hit this condition, it means the allocation is somewhere after the lowest vma->bottom and heap bottom. If there were free spaces between VMAs we would have taken the
vma_abovepath(vma_above->bottom <= vma->top)
This comment will need to be fixed, but let's first resolve my other comments (and then decide what is the correct text here).
Pal/src/host/Linux-SGX/enclave_pages.c, line 143 at r5 (raw file):
* may be used by the enclave). The control returns back to enclave. * 3. Enclave continues the same EACCEPT and the instruction succeeds this time. */ static int get_edmm_page_range(void* start, size_t size, bool executable) {
Why get? I think alloc_edmm_page_range is a better name.
Pal/src/host/Linux-SGX/enclave_pages.c, line 235 at r5 (raw file):
struct heap_vma* vma_above_above = LISTP_PREV_ENTRY(vma_above, &g_heap_vma_list, list); /* Track free space between VMAs while merging `vma_above`. */
free space- > unallocated memory regions
Pal/src/host/Linux-SGX/enclave_pages.c, line 238 at r5 (raw file):
if (g_pal_sec.edmm_enable_heap && vma_above->bottom > current_top) { size_t free_size = vma_above->bottom - current_top; if (free_size) {
This IF is redundant, free_size cannot be zero.
Pal/src/host/Linux-SGX/enclave_pages.c, line 253 at r5 (raw file):
/* Store vma_above->top to check for any free region between vma_above->top and * vma_above_above->bottom. */
This comment is redundant once you change the names. I suggest to simply remove it.
Pal/src/host/Linux-SGX/enclave_pages.c, line 272 at r5 (raw file):
__free_vma(vma_below); vma_below = vma_below_below;
Do I understand correctly that you don't need to add similar logic to this vma_below merging because:
- We already covered the bottom part of the to-allocate memory region (starting with
addr) duringvma_abovemerging above. - It is impossible to have an unallocated space between
vma_belowandvma_below_belowthat needs to be allocated for[addr, size)region.
Pal/src/host/Linux-SGX/enclave_pages.c, line 289 at r5 (raw file):
if (g_pal_sec.edmm_enable_heap && free_cnt == 0 && allocated > 0) { heap_ranges_to_alloc[0].size = allocated; heap_ranges_to_alloc[0].addr = addr;
Something is wrong here... What if we have this scenario:
+ +
+---------------------+-------+ ADDR + SIZE, VMA->top
| FREE |
| FREE |
+-----------+ top
| |
+-----------------------------+ ADDR, VMA->bottom
| VMA_BELOW |
+-----------+ bottom
+ +
Here, the memory region [vma_below->bottom, vma_below->top) is already allocated (and this overlaps with the requested [addr, size)). And the unallocated memory region is [vma_below->top, allocated).
So this line in your code:
heap_ranges_to_alloc[0].addr = addr;
looks incorrect.
Pal/src/host/Linux-SGX/enclave_pages.c, line 363 at r5 (raw file):
* aren't accepted yet (unallocated heap) and call EACCEPT only on those EPC pages. */ if (g_pal_sec.edmm_enable_heap && ret != NULL) { for (int cnt = 0; cnt < EDMM_HEAP_RANGE_CNT; cnt++) {
Please rename cnt -> i
Pal/src/host/Linux-SGX/enclave_pages.c, line 367 at r5 (raw file):
break; int retval = get_edmm_page_range(heap_ranges_to_alloc[cnt].addr, heap_ranges_to_alloc[cnt].size, 1);
Please replace the last argument with proper boolean: 1 -> /*executable=*/true.
Also, are you always setting "executable" permission because in the current code, we don't have actual permission changes? So you're jut setting the maximum permissions possible?
Pal/src/host/Linux-SGX/enclave_pages.c, line 381 at r5 (raw file):
int ret = 0; /* TODO: Should we introduce a compiler switch for EDMM? */ struct edmm_heap_range edmm_free_heap[EDMM_HEAP_RANGE_CNT] = {0};
Please change edmm_free_heap -> heap_ranges_to_free.
Pal/src/host/Linux-SGX/enclave_pages.c, line 382 at r5 (raw file):
/* TODO: Should we introduce a compiler switch for EDMM? */ struct edmm_heap_range edmm_free_heap[EDMM_HEAP_RANGE_CNT] = {0}; int edmm_free_cnt = 0;
Please rename to heap_ranges_to_free_cnt
Pal/src/host/Linux-SGX/enclave_pages.c, line 427 at r5 (raw file):
} freed += MIN(vma->top, addr + size) - MAX(vma->bottom, addr);
Please introduce additional variables for all these and use these additional variables in your new logic below. Currently, you have repetition which is prone to future errors.
Pal/src/host/Linux-SGX/enclave_pages.c, line 432 at r5 (raw file):
size_t range = MIN(vma->top, addr + size) - MAX(vma->bottom, addr); /* if range is contiguous with previous entry, update addr, size accordinlgy*/
Why do you need this "optimization"? To me it looks like an unnecessary complexity. Why would it be worse even if we have two contiguous ranges in two edmm_free_heap entries? This saves us like 5 hardware instructions, who cares.
Pal/src/host/Linux-SGX/enclave_pages.c, line 438 at r5 (raw file):
} else { assert(edmm_free_cnt < EDMM_HEAP_RANGE_CNT); /* found a new non-contiguous range */
This comment will be useless after you remove the "optimization of using the previous entry".
Pal/src/host/Linux-SGX/enclave_pages.c, line 478 at r5 (raw file):
out: if (ret >=0 && g_pal_sec.edmm_enable_heap) { for (int free_cnt = 0; free_cnt < edmm_free_cnt; free_cnt++) {
free_cnt -> i
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Reviewable status: 14 of 15 files reviewed, 22 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 249 at r2 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Ok, thanks for explanation. I think I get it now.
I don't like the names you chose though. We have here two different concepts:
- already-existing logic of "free" memory regions: this means "already allocated but will be zeroed out" (pages exist but their data is erased)
- your newly-added logic of "unallocated" memory regions: this means "not yet allocated"
But you're using
freeterm for both these cases. Let's separate them. I suggest to rename your new variables:
current_top->unallocated_region_addrfree_size->unallocated_region_sizefree_cnt- >heap_ranges_to_alloc_cnt
makes sense but the suggested names seem little long to me. How about?
current_top->unallocated_region_addr->unallocated_start_addrfree_size->unallocated_region_size-> Have removed this variable and simply used original variables for the size arithmetic. It is only used once. I will remove the debug log for the final PR.free_cnt->heap_ranges_to_alloc_cnt->unallocated_cnt
Pal/src/host/Linux-SGX/enclave_pages.c, line 143 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why
get? I thinkalloc_edmm_page_rangeis a better name.
alloc_* could mean similar to SGX1 usage of manipulating already allocated but zeroed out pages. So preferred get as we get these pages from the driver.
I open to changing this but let us see what others think.
Pal/src/host/Linux-SGX/enclave_pages.c, line 235 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
free space- >unallocated memory regions
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 238 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
This IF is redundant,
free_sizecannot be zero.
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 253 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
This comment is redundant once you change the names. I suggest to simply remove it.
I felt this needed to be called out as we switch from using vma_below->top to vma_above->top. But fine with removing this.
Pal/src/host/Linux-SGX/enclave_pages.c, line 272 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Do I understand correctly that you don't need to add similar logic to this
vma_belowmerging because:
- We already covered the bottom part of the to-allocate memory region (starting with
addr) duringvma_abovemerging above.- It is impossible to have an unallocated space between
vma_belowandvma_below_belowthat needs to be allocated for[addr, size)region.
yes, correct for both cases.
Pal/src/host/Linux-SGX/enclave_pages.c, line 289 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Something is wrong here... What if we have this scenario:
+ + +---------------------+-------+ ADDR + SIZE, VMA->top | FREE | | FREE | +-----------+ top | | +-----------------------------+ ADDR, VMA->bottom | VMA_BELOW | +-----------+ bottom + +Here, the memory region
[vma_below->bottom, vma_below->top)is already allocated (and this overlaps with the requested[addr, size)). And the unallocated memory region is[vma_below->top, allocated).So this line in your code:
heap_ranges_to_alloc[0].addr = addr;looks incorrect.
good catch. This should have been MAX(vma_below->top, addr)
Pal/src/host/Linux-SGX/enclave_pages.c, line 363 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please rename
cnt->i
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 367 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please replace the last argument with proper boolean:
1->/*executable=*/true.Also, are you always setting "executable" permission because in the current code, we don't have actual permission changes? So you're jut setting the maximum permissions possible?
yes, currently we always set "executable permission but I want to keep the function prototype so that we can use it in the future.
Pal/src/host/Linux-SGX/enclave_pages.c, line 381 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please change
edmm_free_heap->heap_ranges_to_free.
Done
Pal/src/host/Linux-SGX/enclave_pages.c, line 382 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please rename to
heap_ranges_to_free_cnt
This is only used for indexing heap_ranges_to_free[heap_ranges_to_free_cnt] and it makes the variable too long and somewhat repetitive. How about just free_cnt or simply cnt?
Pal/src/host/Linux-SGX/enclave_pages.c, line 427 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Please introduce additional variables for all these and use these additional variables in your new logic below. Currently, you have repetition which is prone to future errors.
Done.
Pal/src/host/Linux-SGX/enclave_pages.c, line 432 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Why do you need this "optimization"? To me it looks like an unnecessary complexity. Why would it be worse even if we have two contiguous ranges in two
edmm_free_heapentries? This saves us like 5 hardware instructions, who cares.
each new entry in edmm_free_heap corresponds to a range to be freed. Now to free the range, I call free_edmm_page_range() which has the cost of 2 ocalls + 2 IOCTLS. So it is better to consolidate as much as possible before invoking free_edmm_page_range()
Pal/src/host/Linux-SGX/enclave_pages.c, line 478 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
free_cnt->i
Done.
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Reviewed 1 of 1 files at r6.
Reviewable status: all files reviewed, 13 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 249 at r2 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
makes sense but the suggested names seem little long to me. How about?
current_top->unallocated_region_addr->unallocated_start_addrfree_size->unallocated_region_size-> Have removed this variable and simply used original variables for the size arithmetic. It is only used once. I will remove the debug log for the final PR.free_cnt->heap_ranges_to_alloc_cnt->unallocated_cnt
OK, looks much better now!
Pal/src/host/Linux-SGX/enclave_pages.c, line 253 at r5 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
I felt this needed to be called out as we switch from using
vma_below->toptovma_above->top. But fine with removing this.
? What do you mean by "from using vma_below->top..."? There is no vma_below used here.
But I'm fine with keeping the comment.
Pal/src/host/Linux-SGX/enclave_pages.c, line 432 at r5 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
each new entry in
edmm_free_heapcorresponds to a range to be freed. Now to free the range, I callfree_edmm_page_range()which has the cost of2 ocalls + 2 IOCTLS. So it is better to consolidate as much as possible before invokingfree_edmm_page_range()
Good point. But still, does it ever happen? Can you actually have two ranges-to-free being contiguous? I still think that this optimization is premature and doesn't happen in reality (or happens very rarely).
Pal/src/host/Linux-SGX/enclave_pages.c, line 426 at r6 (raw file):
void* free_heap_top = MIN(vma->top, addr + size); void* free_heap_bottom = MAX(vma->bottom, addr); size_t range = free_heap_top - free_heap_bottom;
To be honest, this range variable seems a bit too much :) I would prefer to remove it and just use the subtraction, but I'm not blocking on this.
Pal/src/host/Linux-SGX/enclave_pages.c, line 431 at r6 (raw file):
/* if range is contiguous with previous entry, update addr, size accordinlgy*/ if (free_cnt > 0 && (free_heap_bottom + range) == heap_ranges_to_free[free_cnt-1].addr) {
free_heap_bottom + range -- isn't it just free_heap_top?
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Reviewable status: 14 of 15 files reviewed, 13 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 253 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
? What do you mean by "from using
vma_below->top..."? There is novma_belowused here.But I'm fine with keeping the comment.
Initially before entering the while loop we set to unallocated_start_addr = (vma_below) ? MAX(vma_below->top, vma->bottom) : vma->bottom; and as we go up we set it to unallocated_start_addr = vma_above->top; So thought of calling it out. If you have suggestions to reword it, please let me know.
Pal/src/host/Linux-SGX/enclave_pages.c, line 432 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
Good point. But still, does it ever happen? Can you actually have two ranges-to-free being contiguous? I still think that this optimization is premature and doesn't happen in reality (or happens very rarely).
It can happen but agree it is a little rare. I haven't seen it with our regression tests but we haven't tested real workloads extensively to rule out such a case. Given the cost of enclave exits, I would prefer to have this optimization until we have more results.
I have added assert(0) just to catch this case.
Pal/src/host/Linux-SGX/enclave_pages.c, line 426 at r6 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
To be honest, this
rangevariable seems a bit too much :) I would prefer to remove it and just use the subtraction, but I'm not blocking on this.
I thought we preferred new variables to avoid repetition. Here we reuse range at 3 places.
Pal/src/host/Linux-SGX/enclave_pages.c, line 431 at r6 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
free_heap_bottom + range-- isn't it justfree_heap_top?
yes, we can just use, free_heap_top.
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Reviewed 1 of 11 files at r3, 1 of 1 files at r7.
Reviewable status: all files reviewed, 7 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "fixup! " and "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @mkow, @vijaydhanraj, and @yamahata)
Pal/src/host/Linux-SGX/enclave_pages.c, line 143 at r5 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
alloc_*could mean similar to SGX1 usage of manipulating already allocated but zeroed out pages. So preferredgetas we get thesepagesfrom the driver.I open to changing this but let us see what others think.
Ok, I'm fine with this name.
Pal/src/host/Linux-SGX/enclave_pages.c, line 253 at r5 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
Initially before entering the
whileloop we set tounallocated_start_addr = (vma_below) ? MAX(vma_below->top, vma->bottom) : vma->bottom;and as we go up we set it tounallocated_start_addr = vma_above->top;So thought of calling it out. If you have suggestions to reword it, please let me know.
OK, understood now. Let's keep the comment as is, I'm fine.
Pal/src/host/Linux-SGX/enclave_pages.c, line 432 at r5 (raw file):
Previously, vijaydhanraj (Vijay Dhanraj) wrote…
It can happen but agree it is a little rare. I haven't seen it with our regression tests but we haven't tested real workloads extensively to rule out such a case. Given the cost of enclave exits, I would prefer to have this optimization until we have more results.
I have addedassert(0)just to catch this case.
No, let's not add an assert(0). I don't say that this is an impossible code path. I'm just saying that it is rare (but possible).
I suggest to remove this assert and modify the comment like this:
/* if range is contiguous with previous entry, update addr and size accordingly; this case may be rare
* but the below optimization still saves us 2 OCALLs and 2 IOCTLs, so should be worth it */
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Reviewable status: 1 of 26 files reviewed, 7 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (2 more required, approved so far: ), "DONTMERGE" found in commit messages' one-liners (waiting on @boryspoplawski, @dimakuv, @mkow, and @yamahata)
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Previously, mkow (Michał Kowalczyk) wrote…
ack, good luck then!
Added optimizations to naive EDMM implementation as part of this PR. Also, added a mmap multi-threaded regression test to assess g_heap_vma_lock overhead. Based on my assessment, Hybrid + Lazy free optimization provides much value in the absence of Intel SGX OOT driver optimizations (batch allocation).
Pal/src/host/Linux-SGX/enclave_pages.c, line 432 at r5 (raw file):
Previously, dimakuv (Dmitrii Kuvaiskii) wrote…
No, let's not add an
assert(0). I don't say that this is an impossible code path. I'm just saying that it is rare (but possible).I suggest to remove this assert and modify the comment like this:
/* if range is contiguous with previous entry, update addr and size accordingly; this case may be rare * but the below optimization still saves us 2 OCALLs and 2 IOCTLs, so should be worth it */
Done.
Signed-off-by: Vijay Dhanraj <[email protected]>
This test case passes without EDMM as all the enclave pages are already EADDed but with EDMM, a SIGBUS is generated since pages are only added when needed. Since SIGBUS isn't implemented correctly for lack of memory protection, skipping the mmap test case. Also, updated the mmap test case to remove default signal handler. Signed-off-by: Vijay Dhanraj <[email protected]>
To reduce the enclave exits, pre-allocate minimal heap from top as required by application and allocate the remaining dynamically using EDMM. Signed-off-by: Vijay Dhanraj <[email protected]>
SGX driver allocates EPC pages dynamically by faulting in pages one at a time. This incurs a huge overhead due to enclave exit for each page. To overcome this issue, a new IOCTL has been introduced in the SGX driver which can take the requested range and EAUG all the pages in one shot. This patch updates graphene memory allocator to use the newly added SGX driver IOCTL to pass range of EPC pages to be allocated and on return simply EACCEPTs the EAUG'ed pages. Signed-off-by: Vijay Dhanraj <[email protected]>
This optimization keeps track of free EPC pages and lazily frees them when the amount of EPC that is not freed exceeds a certain threshold that is set from the manifest file `sgx.edmm_lazyfree_th`. This optimization reduces enclave exists and at the same time doesn't hog EPC pages that aren't required anymore. Signed-off-by: Vijay Dhanraj <[email protected]>
Signed-off-by: Vijay Dhanraj <[email protected]>
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Description of the changes
Naive EDMM heap implementation (experimental). This is based on zhtlancer@4f2cfa0 and #234.
How to test this PR?
Add
sgx.edmm_enable_heap = 1to the mainfest file and run the simplehelloworldprogram from regression tests.This change is