Commit 9eea8faf authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: fix __arg_ctx type enforcement for perf_event programs 



Adjust PERF_EVENT type enforcement around __arg_ctx to match exactly
what kernel is doing.

Fixes: 76ec90a9 ("libbpf: warn on unexpected __arg_ctx type when rewriting BTF")
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240125205510.3642094-3-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0e6d0a9d

tools/lib/bpf/libbpf.c

+20 −1
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/filter.h>

#include <linux/limits.h>

#include <linux/perf_event.h>

#include <linux/bpf_perf_event.h>

#include <linux/ring_buffer.h>

#include <sys/epoll.h>

#include <sys/ioctl.h>
@@ -6339,6 +6340,14 @@ static struct { 
	/* all other program types don't have "named" context structs */

};



/* forward declarations for arch-specific underlying types of bpf_user_pt_regs_t typedef,

 * for below __builtin_types_compatible_p() checks;

 * with this approach we don't need any extra arch-specific #ifdef guards

 */

struct pt_regs;

struct user_pt_regs;

struct user_regs_struct;



static bool need_func_arg_type_fixup(const struct btf *btf, const struct bpf_program *prog,

				     const char *subprog_name, int arg_idx,

				     int arg_type_id, const char *ctx_name)
@@ -6379,11 +6388,21 @@ static bool need_func_arg_type_fixup(const struct btf *btf, const struct bpf_pro 
	/* special cases */

	switch (prog->type) {

	case BPF_PROG_TYPE_KPROBE:

	case BPF_PROG_TYPE_PERF_EVENT:

		/* `struct pt_regs *` is expected, but we need to fix up */

		if (btf_is_struct(t) && strcmp(tname, "pt_regs") == 0)

			return true;

		break;

	case BPF_PROG_TYPE_PERF_EVENT:

		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct pt_regs) &&

		    btf_is_struct(t) && strcmp(tname, "pt_regs") == 0)

			return 0;

		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_pt_regs) &&

		    btf_is_struct(t) && strcmp(tname, "user_pt_regs") == 0)

			return 0;

		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_regs_struct) &&

		    btf_is_struct(t) && strcmp(tname, "user_regs_struct") == 0)

			return 0;

		break;

	case BPF_PROG_TYPE_RAW_TRACEPOINT:

	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:

		/* allow u64* as ctx */