From nobody Sat Sep 13 17:02:41 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31CCBC77B73 for ; Mon, 1 May 2023 15:10:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232756AbjEAPKi (ORCPT ); Mon, 1 May 2023 11:10:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232718AbjEAPKf (ORCPT ); Mon, 1 May 2023 11:10:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13AC210E9; Mon, 1 May 2023 08:10:03 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D61AD61090; Mon, 1 May 2023 15:09:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA1C7C433EF; Mon, 1 May 2023 15:09:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1682953791; bh=8mniL9+4FrB6k7OubdeD6PkVGGfKPDXaTg619EQY+6s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i3W99S+Kebonz2Fr8RCco6sseFLpNxS9uPzExEdlbcbg4nz/ApgOoU4JIS9AIVVyQ +6d1GbNxD78qu4UlQiCUo6BSopMqynW0Zxesmp40+9z6+NCJ9fmRqHCmv6TE7G5pnz 2WlN27ilmamAE3tvr9Zc9sUsMge/CQVbgUvNXFHsx42W9lc8LxI7wUekC0YkptFMnm Pz/BfahFtCA6LVkfJvdSWnezlKuoGD5aMzrSX0uvVAhTQfEbh6eCToR8A3LWnWFsFc PRkKQ5pWPoxqfo/PkQTprkZgA/FuY4/LYroRAx4P0LXdQgUMo3oiMOtH7r6AspJFdz TIx6qpKjo1ZIA== From: "Masami Hiramatsu (Google)" To: linux-trace-kernel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Steven Rostedt , mhiramat@kernel.org, Florent Revest , Mark Rutland , Will Deacon , Mathieu Desnoyers , Martin KaFai Lau , bpf@vger.kernel.org Subject: [PATCH v9 07/11] tracing/probes: Add $$args meta argument for all function args Date: Tue, 2 May 2023 00:09:47 +0900 Message-ID: <168295378775.3157983.11834761936789897301.stgit@mhiramat.roam.corp.google.com> X-Mailer: git-send-email 2.40.1.495.gc816e09b53d-goog In-Reply-To: <168295372484.3157983.731333785390494141.stgit@mhiramat.roam.corp.google.com> References: <168295372484.3157983.731333785390494141.stgit@mhiramat.roam.corp.google.com> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) Add the '$$args' meta fetch argument for function-entry probe events. This will be expanded to the all arguments of the function and the tracepoint using BTF function argument information. e.g. # echo 'p vfs_read $$args' >> dynamic_events # echo 'f vfs_write $$args' >> dynamic_events # echo 't sched_overutilized_tp $$args' >> dynamic_events # cat dynamic_events p:kprobes/p_vfs_read_0 vfs_read file=3Dfile buf=3Dbuf count=3Dcount pos=3Dp= os f:fprobes/vfs_write__entry vfs_write file=3Dfile buf=3Dbuf count=3Dcount po= s=3Dpos t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=3Drd overutili= zed=3Doverutilized Signed-off-by: Masami Hiramatsu (Google) --- Changes in v6: - update patch description. --- kernel/trace/trace_fprobe.c | 21 ++++++++-- kernel/trace/trace_kprobe.c | 23 +++++++++-- kernel/trace/trace_probe.c | 93 +++++++++++++++++++++++++++++++++++++++= ++++ kernel/trace/trace_probe.h | 9 ++++ 4 files changed, 138 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index a34081113fa8..aa3e4ac9c259 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -924,14 +924,16 @@ static int __trace_fprobe_create(int argc, const char= *argv[]) * FETCHARG:TYPE : use TYPE instead of unsigned long. */ struct trace_fprobe *tf =3D NULL; - int i, len, ret =3D 0; + int i, len, new_argc =3D 0, ret =3D 0; bool is_return =3D false; char *symbol =3D NULL, *tmp =3D NULL; const char *event =3D NULL, *group =3D FPROBE_EVENT_SYSTEM; + const char **new_argv =3D NULL; int maxactive =3D 0; char buf[MAX_EVENT_NAME_LEN]; char gbuf[MAX_EVENT_NAME_LEN]; char sbuf[KSYM_NAME_LEN]; + char abuf[MAX_BTF_ARGS_LEN]; bool is_tracepoint =3D false; struct tracepoint *tpoint =3D NULL; struct traceprobe_parse_context ctx =3D { @@ -1037,9 +1039,22 @@ static int __trace_fprobe_create(int argc, const cha= r *argv[]) } else ctx.funcname =3D symbol; =20 + argc -=3D 2; argv +=3D 2; + new_argv =3D traceprobe_expand_meta_args(argc, argv, &new_argc, + abuf, MAX_BTF_ARGS_LEN, &ctx); + if (IS_ERR(new_argv)) { + ret =3D PTR_ERR(new_argv); + new_argv =3D NULL; + goto out; + } + if (new_argv) { + argc =3D new_argc; + argv =3D new_argv; + } + /* setup a probe */ tf =3D alloc_trace_fprobe(group, event, symbol, tpoint, maxactive, - argc - 2, is_return); + argc, is_return); if (IS_ERR(tf)) { ret =3D PTR_ERR(tf); /* This must return -ENOMEM, else there is a bug */ @@ -1051,7 +1066,6 @@ static int __trace_fprobe_create(int argc, const char= *argv[]) tf->mod =3D __module_text_address( (unsigned long)tf->tpoint->probestub); =20 - argc -=3D 2; argv +=3D 2; /* parse arguments */ for (i =3D 0; i < argc && i < MAX_TRACE_ARGS; i++) { trace_probe_log_set_index(i + 2); @@ -1080,6 +1094,7 @@ static int __trace_fprobe_create(int argc, const char= *argv[]) =20 out: trace_probe_log_clear(); + kfree(new_argv); kfree(symbol); return ret; =20 diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index aff6c1a5e161..2d7c0188c2b1 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -732,9 +732,10 @@ static int __trace_kprobe_create(int argc, const char = *argv[]) * FETCHARG:TYPE : use TYPE instead of unsigned long. */ struct trace_kprobe *tk =3D NULL; - int i, len, ret =3D 0; + int i, len, new_argc =3D 0, ret =3D 0; bool is_return =3D false; char *symbol =3D NULL, *tmp =3D NULL; + const char **new_argv =3D NULL; const char *event =3D NULL, *group =3D KPROBE_EVENT_SYSTEM; enum probe_print_type ptype; int maxactive =3D 0; @@ -742,6 +743,7 @@ static int __trace_kprobe_create(int argc, const char *= argv[]) void *addr =3D NULL; char buf[MAX_EVENT_NAME_LEN]; char gbuf[MAX_EVENT_NAME_LEN]; + char abuf[MAX_BTF_ARGS_LEN]; struct traceprobe_parse_context ctx =3D { .flags =3D TPARG_FL_KERNEL }; =20 switch (argv[0][0]) { @@ -854,19 +856,31 @@ static int __trace_kprobe_create(int argc, const char= *argv[]) event =3D buf; } =20 + argc -=3D 2; argv +=3D 2; + ctx.funcname =3D symbol; + new_argv =3D traceprobe_expand_meta_args(argc, argv, &new_argc, + abuf, MAX_BTF_ARGS_LEN, &ctx); + if (IS_ERR(new_argv)) { + ret =3D PTR_ERR(new_argv); + new_argv =3D NULL; + goto out; + } + if (new_argv) { + argc =3D new_argc; + argv =3D new_argv; + } + /* setup a probe */ tk =3D alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive, - argc - 2, is_return); + argc, is_return); if (IS_ERR(tk)) { ret =3D PTR_ERR(tk); /* This must return -ENOMEM, else there is a bug */ WARN_ON_ONCE(ret !=3D -ENOMEM); goto out; /* We know tk is not allocated */ } - argc -=3D 2; argv +=3D 2; =20 /* parse arguments */ - ctx.funcname =3D symbol; for (i =3D 0; i < argc && i < MAX_TRACE_ARGS; i++) { trace_probe_log_set_index(i + 2); ctx.offset =3D 0; @@ -894,6 +908,7 @@ static int __trace_kprobe_create(int argc, const char *= argv[]) =20 out: trace_probe_log_clear(); + kfree(new_argv); kfree(symbol); return ret; =20 diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 346673e9dfd4..4c3c70862a9a 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -451,12 +451,18 @@ static const struct fetch_type *parse_btf_arg_type(in= t arg_idx, =20 return find_fetch_type(typestr, ctx->flags); } + #else static struct btf *traceprobe_get_btf(void) { return NULL; } =20 +static const struct btf_param *find_btf_func_param(const char *funcname, s= 32 *nr) +{ + return ERR_PTR(-EOPNOTSUPP); +} + static int parse_btf_arg(const char *varname, struct fetch_insn *code, struct traceprobe_parse_context *ctx) { @@ -1080,6 +1086,93 @@ void traceprobe_free_probe_arg(struct probe_arg *arg) kfree(arg->fmt); } =20 +/* Return new_argv which must be freed after use */ +const char **traceprobe_expand_meta_args(int argc, const char *argv[], + int *new_argc, char *buf, int bufsize, + struct traceprobe_parse_context *ctx) +{ + struct btf *btf =3D traceprobe_get_btf(); + const struct btf_param *params =3D NULL; + int i, j, used, ret, args_idx =3D -1; + const char **new_argv =3D NULL; + int nr_skipped; + + /* The first argument of tracepoint should be skipped. */ + nr_skipped =3D ctx->flags & TPARG_FL_TPOINT ? 1 : 0; + for (i =3D 0; i < argc; i++) + if (!strcmp(argv[i], "$$args")) { + trace_probe_log_set_index(i + 2); + + if (!tparg_is_function_entry(ctx->flags)) { + trace_probe_log_err(0, NOFENTRY_ARGS); + return ERR_PTR(-EINVAL); + } + + if (args_idx >=3D 0) { + trace_probe_log_err(0, DOUBLE_ARGS); + return ERR_PTR(-EINVAL); + } + + args_idx =3D i; + params =3D find_btf_func_param(ctx->funcname, &ctx->nr_params); + if (IS_ERR(params)) { + trace_probe_log_err(0, NOSUP_BTFARG); + return (const char **)params; + } + ctx->params =3D params; + } + + /* If target has no arguments, return NULL and the original argc. */ + if (args_idx < 0 || ctx->nr_params < nr_skipped) { + *new_argc =3D argc; + return NULL; + } + + *new_argc =3D argc - 1 + ctx->nr_params - nr_skipped; + + new_argv =3D kcalloc(*new_argc, sizeof(char *), GFP_KERNEL); + if (!new_argv) + return ERR_PTR(-ENOMEM); + + for (i =3D 0; i < args_idx; i++) + new_argv[i] =3D argv[i]; + + used =3D 0; + trace_probe_log_set_index(args_idx + 2); + for (i =3D 0; i < ctx->nr_params - nr_skipped; i++) { + const char *name; + + name =3D btf_name_by_offset(btf, params[i + nr_skipped].name_off); + if (!name) { + trace_probe_log_err(0, NO_BTF_ENTRY); + ret =3D -ENOENT; + goto error; + } + ret =3D snprintf(buf + used, bufsize - used, "%s", name); + if (ret >=3D bufsize - used) { + trace_probe_log_err(0, ARGS_2LONG); + ret =3D -E2BIG; + goto error; + } + new_argv[args_idx + i] =3D buf + used; + used +=3D ret + 1; /* include null byte */ + } + + /* Note: we have to skip $$args */ + j =3D args_idx + ctx->nr_params - nr_skipped; + for (i =3D args_idx + 1; i < argc; i++, j++) { + if (WARN_ON(j >=3D *new_argc)) + goto error; + new_argv[j] =3D argv[i]; + } + + return new_argv; + +error: + kfree(new_argv); + return ERR_PTR(ret); +} + int traceprobe_update_arg(struct probe_arg *arg) { struct fetch_insn *code =3D arg->code; diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 9ea5c7e8753f..8c5b029c5d62 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -33,6 +33,7 @@ #define MAX_ARGSTR_LEN 63 #define MAX_ARRAY_LEN 64 #define MAX_ARG_NAME_LEN 32 +#define MAX_BTF_ARGS_LEN 128 #define MAX_STRING_SIZE PATH_MAX =20 /* Reserved field names */ @@ -387,6 +388,9 @@ struct traceprobe_parse_context { extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, const char *argv, struct traceprobe_parse_context *ctx); +const char **traceprobe_expand_meta_args(int argc, const char *argv[], + int *new_argc, char *buf, int bufsize, + struct traceprobe_parse_context *ctx); =20 extern int traceprobe_update_arg(struct probe_arg *arg); extern void traceprobe_free_probe_arg(struct probe_arg *arg); @@ -481,7 +485,10 @@ extern int traceprobe_define_arg_fields(struct trace_e= vent_call *event_call, C(NO_EP_FILTER, "No filter rule after 'if'"), \ C(NOSUP_BTFARG, "BTF is not available or not supported"), \ C(NO_BTFARG, "This variable is not found at this probe point"),\ - C(NO_BTF_ENTRY, "No BTF entry for this probe point"), + C(NO_BTF_ENTRY, "No BTF entry for this probe point"), \ + C(NOFENTRY_ARGS, "$$args can be used only on function entry"), \ + C(DOUBLE_ARGS, "$$args can be used only once in the parameter"), \ + C(ARGS_2LONG, "$$args failed because the argument is too long"), =20 #undef C #define C(a, b) TP_ERR_##a