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libbpf-tools/profile: Add support for PID-namespacing #5152

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libbpf-tools/profile: Add support for PID-namespacing #5152

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7a3843f
libbpf-tools/profile: Add support for PID-namespacing
ekyooo Nov 20, 2024
405c48f
libbpf_tools/profile: Support PID namespace mapping if available in t…
ekyooo Nov 21, 2024
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20 changes: 17 additions & 3 deletions libbpf-tools/profile.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,9 @@ const volatile bool user_stacks_only = false;
const volatile bool include_idle = false;
const volatile bool filter_by_pid = false;
const volatile bool filter_by_tid = false;
const volatile bool use_pidns = false;
const volatile __u64 pidns_dev = 0;
const volatile __u64 pidns_ino = 0;

struct {
__uint(type, BPF_MAP_TYPE_STACK_TRACE);
Expand Down Expand Up @@ -47,12 +50,23 @@ struct {
SEC("perf_event")
int do_perf_event(struct bpf_perf_event_data *ctx)
{
u64 id = bpf_get_current_pid_tgid();
u32 pid = id >> 32;
u32 tid = id;
u64 *valp;
static const u64 zero;
struct key_t key = {};
u64 id;
u32 pid;
u32 tid;
struct bpf_pidns_info ns = {};

if (use_pidns && !bpf_get_ns_current_pid_tgid(pidns_dev, pidns_ino, &ns,
sizeof(struct bpf_pidns_info))) {
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Use ns for sizeof instead of the type name?

pid = ns.tgid;
tid = ns.pid;
} else {
id = bpf_get_current_pid_tgid();
pid = id >> 32;
tid = id;
}

if (!include_idle && tid == 0)
return 0;
Expand Down
22 changes: 22 additions & 0 deletions libbpf-tools/profile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include <asm/unistd.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include <sys/stat.h>
#include "profile.h"
#include "profile.skel.h"
#include "trace_helpers.h"
Expand Down Expand Up @@ -506,6 +507,23 @@ static int print_counts(int counts_map, int stack_map)
return ret;
}

static int set_pidns(const struct profile_bpf *obj)
{
struct stat statbuf;

if (!probe_bpf_ns_current_pid_tgid())
return -EPERM;

if (stat("/proc/self/ns/pid", &statbuf) == -1)
return -errno;

obj->rodata->use_pidns = true;
obj->rodata->pidns_dev = statbuf.st_dev;
obj->rodata->pidns_ino = statbuf.st_ino;

return 0;
}

static void print_headers()
{
int i;
Expand Down Expand Up @@ -595,6 +613,10 @@ int main(int argc, char **argv)
env.perf_max_stack_depth * sizeof(unsigned long));
bpf_map__set_max_entries(obj->maps.stackmap, env.stack_storage_size);

err = set_pidns(obj);
if (err && env.verbose)
fprintf(stderr, "failed to translate pidns: %s\n", strerror(-err));

err = profile_bpf__load(obj);
if (err) {
fprintf(stderr, "failed to load BPF programs\n");
Expand Down
22 changes: 22 additions & 0 deletions libbpf-tools/trace_helpers.c
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Expand Up @@ -1248,6 +1248,28 @@ bool probe_ringbuf()
return true;
}

bool probe_bpf_ns_current_pid_tgid(void)
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I would first add a commit introducing this helper, then using it in another commit in profile.c.
What do you think?

{
int fd, insn_cnt;
struct bpf_insn insns[] = {
{ .code = BPF_ALU64 | BPF_MOV | BPF_X, .dst_reg = 3, .src_reg = BPF_REG_10 },
{ .code = BPF_ALU64 | BPF_ADD | BPF_K, .dst_reg = 3, .imm = -8 },
{ .code = BPF_ALU64 | BPF_MOV | BPF_K, .dst_reg = 1, .imm = 0 },
{ .code = BPF_ALU64 | BPF_MOV | BPF_K, .dst_reg = 2, .imm = 0 },
{ .code = BPF_ALU64 | BPF_MOV | BPF_K, .dst_reg = 4, .imm = 8 },
{ .code = BPF_JMP | BPF_CALL, .imm = BPF_FUNC_get_ns_current_pid_tgid },
{ .code = BPF_JMP | BPF_EXIT },
};

insn_cnt = sizeof(insns) / sizeof(struct bpf_insn);
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Suggested change
insn_cnt = sizeof(insns) / sizeof(struct bpf_insn);
insn_cnt = sizeof(insns) / sizeof(insns[0]);

This way, you do not have problem if one day we need to change the type.


fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL);
if (fd >= 0)
close(fd);

return fd >= 0;
}

int split_convert(char *s, const char* delim, void *elems, size_t elems_size,
size_t elem_size, convert_fn_t convert)
{
Expand Down
1 change: 1 addition & 0 deletions libbpf-tools/trace_helpers.h
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Expand Up @@ -107,6 +107,7 @@ bool module_btf_exists(const char *mod);

bool probe_tp_btf(const char *name);
bool probe_ringbuf();
bool probe_bpf_ns_current_pid_tgid(void);

typedef int (*convert_fn_t)(const char *src, void *dest);
int split_convert(char *s, const char* delim, void *elems, size_t elems_size,
Expand Down
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