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From: Andrii Nakryiko <andrii@kernel.org>
To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
	martin.lau@kernel.org
Cc: andrii@kernel.org, kernel-team@meta.com
Subject: [PATCH v2 bpf-next 2/7] libbpf: fix __arg_ctx type enforcement for perf_event programs
Date: Thu, 25 Jan 2024 12:55:05 -0800	[thread overview]
Message-ID: <20240125205510.3642094-3-andrii@kernel.org> (raw)
In-Reply-To: <20240125205510.3642094-1-andrii@kernel.org>

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

Fixes: 76ec90a996e3 ("libbpf: warn on unexpected __arg_ctx type when rewriting BTF")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 41ab7a21f868..db65ea59a05a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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 */
-- 
2.34.1


  parent reply	other threads:[~2024-01-25 20:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-25 20:55 [PATCH v2 bpf-next 0/7] Trusted PTR_TO_BTF_ID arg support in global subprogs Andrii Nakryiko
2024-01-25 20:55 ` [PATCH v2 bpf-next 1/7] libbpf: integrate __arg_ctx feature detector into kernel_supports() Andrii Nakryiko
2024-01-25 20:55 ` Andrii Nakryiko [this message]
2024-01-26 13:24   ` [PATCH v2 bpf-next 2/7] libbpf: fix __arg_ctx type enforcement for perf_event programs Eduard Zingerman
2024-01-26 19:06     ` Andrii Nakryiko
2024-01-26 21:32       ` Eduard Zingerman
2024-01-26 22:21         ` Andrii Nakryiko
2024-01-25 20:55 ` [PATCH v2 bpf-next 3/7] bpf: move arg:ctx type enforcement check inside the main logic loop Andrii Nakryiko
2024-01-25 20:55 ` [PATCH v2 bpf-next 4/7] bpf: add __arg_trusted global func arg tag Andrii Nakryiko
2024-01-25 20:55 ` [PATCH v2 bpf-next 5/7] bpf: add arg:maybe_null tag to be combined with trusted pointers Andrii Nakryiko
2024-01-25 20:55 ` [PATCH v2 bpf-next 6/7] libbpf: add __arg_trusted and __arg_maybe_null tag macros Andrii Nakryiko
2024-01-25 20:55 ` [PATCH v2 bpf-next 7/7] selftests/bpf: add trusted global subprog arg tests Andrii Nakryiko
2024-01-29 17:29 ` [PATCH v2 bpf-next 0/7] Trusted PTR_TO_BTF_ID arg support in global subprogs Eduard Zingerman
2024-01-29 20:50 ` patchwork-bot+netdevbpf

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