flamenco, vm: halve size of physical stack region

firedancer-io · Oct 10, 2024 · 832f6a3 · 832f6a3
1 parent 161f74e
commit 832f6a3
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Showing 6 changed files with 22 additions and 11 deletions.
diff --git a/contrib/test/test-vectors-fixtures/syscall-fixtures/cpi.list b/contrib/test/test-vectors-fixtures/syscall-fixtures/cpi.list
@@ -1 +0,0 @@
-dump/test-vectors/syscall/fixtures/cpi/cpi_callee_prog_in_txn_check.fix

diff --git a/contrib/test/test-vectors-fixtures/test-vectors-commit-sha.txt b/contrib/test/test-vectors-fixtures/test-vectors-commit-sha.txt
@@ -1 +1 @@
-c21493260e92093295f69a629426bd90468a2e84
+06227823191776a59cb4c097fdb0780d7ba78ee9
diff --git a/src/flamenco/vm/fd_vm.h b/src/flamenco/vm/fd_vm.h
@@ -196,7 +196,7 @@ FD_PROTOTYPES_BEGIN
    integer power of 2.  FOOTPRINT is a multiple of align. 
    These are provided to facilitate compile time declarations. */
 #define FD_VM_ALIGN     (8UL     )
-#define FD_VM_FOOTPRINT (789408UL)
+#define FD_VM_FOOTPRINT (527264UL)
 
 /* fd_vm_{align,footprint} give the needed alignment and footprint
    of a memory region suitable to hold an fd_vm_t.

diff --git a/src/flamenco/vm/fd_vm_base.h b/src/flamenco/vm/fd_vm_base.h
@@ -158,9 +158,9 @@ FD_PROTOTYPES_END
 /* VM stack constants */
 
 #define FD_VM_STACK_FRAME_MAX (64UL)
-#define FD_VM_STACK_FRAME_SZ  (0x1000UL) /* FIXME: SHOULD THIS MACH FD_VM_STACK_FRAME_SIZE BELOW? */
+#define FD_VM_STACK_FRAME_SZ  FD_VM_STACK_FRAME_SIZE
 #define FD_VM_STACK_GUARD_SZ  (0x1000UL)
-#define FD_VM_STACK_MAX       (FD_VM_STACK_FRAME_MAX*(FD_VM_STACK_FRAME_SZ+FD_VM_STACK_GUARD_SZ))
+#define FD_VM_STACK_MAX       (FD_VM_STACK_FRAME_MAX*(FD_VM_STACK_FRAME_SZ))
 
 /* VM heap constants */
 

diff --git a/src/flamenco/vm/fd_vm_private.h b/src/flamenco/vm/fd_vm_private.h
@@ -312,16 +312,28 @@ fd_vm_mem_haddr( fd_vm_t const *    vm,
   ulong vaddr_hi  = vaddr >> 32;
   ulong region    = fd_ulong_min( vaddr_hi, 5UL );
   ulong offset    = vaddr & 0xffffffffUL;
-  ulong region_sz = (ulong)vm_region_sz[ region ];
-  ulong sz_max    = region_sz - fd_ulong_min( offset, region_sz );
 
   /* Stack memory regions have 4kB unmapped "gaps" in-between each frame.
-     https://github.com/solana-labs/rbpf/blob/b503a1867a9cfa13f93b4d99679a17fe219831de/src/memory_region.rs#L141
+    https://github.com/solana-labs/rbpf/blob/b503a1867a9cfa13f93b4d99679a17fe219831de/src/memory_region.rs#L141
     */
-  if( FD_UNLIKELY( ( region == 2 ) && !!( vaddr & 0x1000 ) ) ) {
-    return sentinel;
+  if ( FD_UNLIKELY( region == 2UL ) ) {
+    /* If an access starts in a gap region, that is an access violation */
+    if ( !!( vaddr & 0x1000 ) ) {
+      return sentinel;
+    }
+
+    /* To account for the fact that we have gaps in the virtual address space but not in the 
+       physical address space, we need to subtract from the offset the size of all the virtual
+       gap frames underneath it.
+       
+       https://github.com/solana-labs/rbpf/blob/b503a1867a9cfa13f93b4d99679a17fe219831de/src/memory_region.rs#L147-L149 */
+    ulong gap_mask = 0xFFFFFFFFFFFFF000;
+    offset = ( ( offset & gap_mask ) >> 1 ) | ( offset & ~gap_mask ); 
   }
 
+  ulong region_sz = (ulong)vm_region_sz[ region ];
+  ulong sz_max    = region_sz - fd_ulong_min( offset, region_sz );
+
   if( region==4UL ) {
     return fd_vm_find_input_mem_region( vm, offset, sz, write, sentinel, is_multi_region );
   }

diff --git a/src/flamenco/vm/test_vm_base.c b/src/flamenco/vm/test_vm_base.c
@@ -53,7 +53,7 @@ FD_STATIC_ASSERT( FD_VM_SHADOW_REG_CNT== 4UL, vm_reg );
 FD_STATIC_ASSERT( FD_VM_STACK_FRAME_MAX==64UL,          vm_stack );
 FD_STATIC_ASSERT( FD_VM_STACK_FRAME_SZ ==0x1000UL,      vm_stack );
 FD_STATIC_ASSERT( FD_VM_STACK_GUARD_SZ ==0x1000UL,      vm_stack );
-FD_STATIC_ASSERT( FD_VM_STACK_MAX      ==64UL*0x2000UL, vm_stack );
+FD_STATIC_ASSERT( FD_VM_STACK_MAX      ==64UL*0x1000UL, vm_stack );
 
 FD_STATIC_ASSERT( FD_VM_HEAP_DEFAULT== 32UL*1024UL, vm_heap );
 FD_STATIC_ASSERT( FD_VM_HEAP_MAX    ==256UL*1024UL, vm_heap );