[3/3] Revert "bpf: Support __nullable argument suffix for tp_btf"

Commit Message

Feng Yang Feb. 10, 2025, 7:35 a.m. UTC

From: Feng Yang <[e-mail]>

This commit 838a10bd2ebf 
("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL") 
has already resolved the issue, so we can roll back these patches.
This reverts commit 8aeaed21befc90f27f4fca6dd190850d97d2e9e3.

Signed-off-by: Feng Yang <[e-mail]>
---
 kernel/bpf/btf.c      |  3 ---
 kernel/bpf/verifier.c | 36 ++++--------------------------------
 2 files changed, 4 insertions(+), 35 deletions(-)

Comments

Alexei Starovoitov Feb. 10, 2025, 7:38 a.m. UTC | #1

On Sun, Feb 9, 2025 at 11:35 PM Feng Yang <[e-mail]> wrote:
>
> From: Feng Yang <[e-mail]>
>
> This commit 838a10bd2ebf
> ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL")
> has already resolved the issue, so we can roll back these patches.
> This reverts commit 8aeaed21befc90f27f4fca6dd190850d97d2e9e3.
>
> Signed-off-by: Feng Yang <[e-mail]>
> ---
>  kernel/bpf/btf.c      |  3 ---
>  kernel/bpf/verifier.c | 36 ++++--------------------------------
>  2 files changed, 4 insertions(+), 35 deletions(-)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 9433b6467bbe..e66f98b493d0 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -6683,9 +6683,6 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
>         if (prog_args_trusted(prog))
>                 info->reg_type |= PTR_TRUSTED;
>
> -       if (btf_param_match_suffix(btf, &args[arg], "__nullable"))
> -               info->reg_type |= PTR_MAYBE_NULL;
> -

Nack.
This is still useful and necessary.

Patch

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 9433b6467bbe..e66f98b493d0 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6683,9 +6683,6 @@  bool btf_ctx_access(int off, int size, enum bpf_access_type type,
 	if (prog_args_trusted(prog))
 		info->reg_type |= PTR_TRUSTED;
 
-	if (btf_param_match_suffix(btf, &args[arg], "__nullable"))
-		info->reg_type |= PTR_MAYBE_NULL;
-
 	if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
 		struct btf *btf = prog->aux->attach_btf;
 		const struct btf_type *t;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9971c03adfd5..3c40b5b18f46 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -28,8 +28,6 @@ 
 #include <linux/cpumask.h>
 #include <linux/bpf_mem_alloc.h>
 #include <net/xdp.h>
-#include <linux/trace_events.h>
-#include <linux/kallsyms.h>
 
 #include "disasm.h"
 
@@ -22509,13 +22507,11 @@  int bpf_check_attach_target(struct bpf_verifier_log *log,
 {
 	bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
 	bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING;
-	char trace_symbol[KSYM_SYMBOL_LEN];
 	const char prefix[] = "btf_trace_";
-	struct bpf_raw_event_map *btp;
 	int ret = 0, subprog = -1, i;
 	const struct btf_type *t;
 	bool conservative = true;
-	const char *tname, *fname;
+	const char *tname;
 	struct btf *btf;
 	long addr = 0;
 	struct module *mod = NULL;
@@ -22655,34 +22651,10 @@  int bpf_check_attach_target(struct bpf_verifier_log *log,
 			return -EINVAL;
 		}
 		tname += sizeof(prefix) - 1;
-
-		/* The func_proto of "btf_trace_##tname" is generated from typedef without argument
-		 * names. Thus using bpf_raw_event_map to get argument names.
-		 */
-		btp = bpf_get_raw_tracepoint(tname);
-		if (!btp)
+		t = btf_type_by_id(btf, t->type);
+		if (!btf_type_is_ptr(t))
+			/* should never happen in valid vmlinux build */
 			return -EINVAL;
-		fname = kallsyms_lookup((unsigned long)btp->bpf_func, NULL, NULL, NULL,
-					trace_symbol);
-		bpf_put_raw_tracepoint(btp);
-
-		if (fname)
-			ret = btf_find_by_name_kind(btf, fname, BTF_KIND_FUNC);
-
-		if (!fname || ret < 0) {
-			bpf_log(log, "Cannot find btf of tracepoint template, fall back to %s%s.\n",
-				prefix, tname);
-			t = btf_type_by_id(btf, t->type);
-			if (!btf_type_is_ptr(t))
-				/* should never happen in valid vmlinux build */
-				return -EINVAL;
-		} else {
-			t = btf_type_by_id(btf, ret);
-			if (!btf_type_is_func(t))
-				/* should never happen in valid vmlinux build */
-				return -EINVAL;
-		}
-
 		t = btf_type_by_id(btf, t->type);
 		if (!btf_type_is_func_proto(t))
 			/* should never happen in valid vmlinux build */