From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CWXP265CU008.outbound.protection.outlook.com (mail-ukwestazon11020140.outbound.protection.outlook.com [52.101.195.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A9C9D35B63C; Fri, 21 Aug 2026 20:49:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.195.140 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787345390; cv=fail; b=IrfbBvLpvEUzPzAlZpWC8/cRJS8gm15sKA1qe0tYvBbeg2D6QohtAr20dSOG9cQEvz/UV/5wj4OHTSpN/l0PvxMParSrL71iex1U6ciPNH1R/Qp1nrEEJvswCSaqmBnESew/ec6xvyoy7Y63QyMv1MN9JQjVTzIVxmkYZO66cro= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787345390; c=relaxed/simple; bh=8uIAm1LzpZN8dLHCT4WDGOZRUNZ94W4NDRqcsRzTXeI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=fGHUXIF6Ir1ibVJEEl+y4s4QdcuhIAtRiAM4U/dziJkbmzoPbH22GI/ZNEO7uevegDtDpXD5tfTJd0Qtwek3YSE+Ygh8i9E1/wjpIjupKCTPMk9zRRdGtnlNuiQj4zejjCEYUTqsOocRYpSprvIhJKf0nNKA+8q0OrsIulPYn5E= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=atomlin.com; spf=pass smtp.mailfrom=atomlin.com; arc=fail smtp.client-ip=52.101.195.140 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=atomlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=atomlin.com ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=ttn9FWMU6NVsrAuiGDiEUvVj3VEUrgHmQgtgFUcfuuK0yoVEmq8q19p1gEHgS5n4EdXE+AEmlleq+gJN+BlzzEQDxVEOeM91n9amVbyagkPW9NzxhCr8Z/o1+tzg3qySItC9fEulO87vlP3Ky25QXh+VuDlWxo9+XgBJN32nMHXB2g20OaahXR/Tnb/Lhzh9IcZPAAkKUfsUwIJta/968nd6NRYZpFMF6ELOthn3/Wu0c/Woo0NhZKEMzM4aGRXAx6KCORoGLsiTX9e7UzIYNrZ0UVrj2866FTVVAcUfIcnO/9gYr4GDqZdhHvxPbAqkTemnWvcfqC0zPtwvIM8Yng== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:MIME-Version; bh=ma9hmAqw2nMZX34p9OgclZuvb3Y8EY2aa4p184hr2VI=; b=wBL/SvhgD7fTCSH/AQZ7FHIx6GrsrN+gYfz56bw8bxOxioPWgyn1UZW2bR16eEeCDSDEFmCfP1RCxMPCYdUxni0PbkWn4/OV5xGUGbVzAuNWyN45nufJEw9qLptP50OlvM0JdMqOFHkfqPNsVuEJBJUyjW8eSgdOyaS+Cn5qP8U+QByYzQvNNozEDtFFAgYKpBx1oBDT/D20hXSP6tsHoYTneZCTy8zoyOdpJ5D+p6bKudZShbGL9L1CAkLXIf8t4u2r5JHFtGTyBZ48Gzck+57OEKVhXhH1EjBlr+g5en7R4uXQRy4u444ZdHfeE/3Hm6gfE1adkcExN+YGQkblcA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=atomlin.com; dmarc=pass action=none header.from=atomlin.com; dkim=pass header.d=atomlin.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=atomlin.com; Received: from CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM (2603:10a6:400:183::5) by LO2P123MB6104.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:25b::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.339.10; Fri, 21 Aug 2026 20:49:46 +0000 Received: from CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM ([fe80::cec4:77ab:262e:d230]) by CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM ([fe80::cec4:77ab:262e:d230%4]) with mapi id 15.21.0339.010; Fri, 21 Aug 2026 20:49:46 +0000 From: Aaron Tomlin To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org Cc: mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, james.clark@linaro.org, howardchu95@gmail.com, atomlin@atomlin.com, neelx@suse.com, chjohnst@mail.com, sean@ashe.io, steve@abita.co, rishil1999@outlook.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH perf-tools-next v4 3/4] perf trace: Enhance BTF type formatting to symbolise kernel function pointers Date: Fri, 21 Aug 2026 16:49:29 -0400 Message-ID: <20260821204930.679027-4-atomlin@atomlin.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260821204930.679027-1-atomlin@atomlin.com> References: <20260821204930.679027-1-atomlin@atomlin.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: BN1PR13CA0004.namprd13.prod.outlook.com (2603:10b6:408:e2::9) To CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM (2603:10a6:400:183::5) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CWLP123MB6607:EE_|LO2P123MB6104:EE_ X-MS-Office365-Filtering-Correlation-Id: 5f4ed5c2-ad4e-414e-0205-08deffc5bbe7 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|7416014|376014|1800799024|56012099006|10067099003|3023799007|6133799003|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(366016)(7416014)(376014)(1800799024)(56012099006)(10067099003)(3023799007)(6133799003)(22082099003)(18002099003);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?zGeGLbO9rD3ZTcmUqgXJVrERt1gvgjg4C+t7i4ExjoVUHNz8HBNNVK8nYKL4?= =?us-ascii?Q?F1foWVlnlkTW6HA2H8q0P1kZZ4xeqgzHP7IefVxCBpmCliUpv46TFYPMNsmi?= =?us-ascii?Q?jUe4xNdDfIe7CetoCrG3BsUuOERt1k7qLhDQlM4g2YoU/AFSyxEpnMF+/kkK?= =?us-ascii?Q?DYV6FDX7lelMReqEE0Om+IpxDXIQtQ16FXa/HXiIun4z8rVRs4XKZfMXOUsb?= =?us-ascii?Q?zcnWKXzoeKIhA9fLbUorSPvSjlV7fAuqlvNc62ahS/UCSiZ7EHYGrwhDmBI/?= =?us-ascii?Q?zD26jvGeQxvSkdQCpsXkyNwThCNzxn+hKml4JQb8RL+G9EBy8DWn4i5fDRSI?= =?us-ascii?Q?NWmuqcqy62rqJkwKYkB4hsO0a199LF9wKpHpgxVsBMjaJppFdWSv58D7XxXM?= =?us-ascii?Q?P+os4ZoyVfI3Ap3jWuheNQLRhIw1U1GM+IY+T0U3s8zKnXKfFPLTgn0GEitD?= =?us-ascii?Q?ApI5IqTwTlMeTH+rFCWo26Mo2WCDh97FfBdmfYDKaqnBi0JjWdYxNzzhLBSb?= =?us-ascii?Q?9bpmL0eOdjbfBysgWSPjrISUXrDwG5RE/Nunc0ZgR5f9yufUJyaXkcZ9+17y?= =?us-ascii?Q?4CmijW1TIr4XpMl5MbG4hWMMleeKshGs57UuGNq5pBRseO0iRcg768uObVLu?= =?us-ascii?Q?QTnaOVgSovnZfDfYzpMVNVJeo61/jMFKeBIeLa9jhDaps769UNT6DFekEy51?= =?us-ascii?Q?IDiKM2aY72Z9a5yIQwY2RfvyGvV73kMyztZ1u7XW8tMP0epguSE5i/qFdGrm?= =?us-ascii?Q?eprl6iD7pFk2cgAXMk/VG+eJlqjrYe5N/w4pSEUpaJ5u0Fr0XjXHGKUZkLKR?= =?us-ascii?Q?bxC5eMlpca9lBH9mmbL6seclTPJuOyIesAUdAigFPoGswyS7gN0Z8tKu4JuO?= =?us-ascii?Q?rsoq4Hb5g+g7yCy0dydh/RvjQ+ocem95IgeYP9egQP0Dek5KxntDeugKMjUe?= =?us-ascii?Q?VLSKADo8iURh5WxhdnDtQxRTQ99IU+sfYZqDD3yK6UGatyKB1WPHkL1xbFc2?= =?us-ascii?Q?mKMJPbIlTkLNsSqHdWzHEHdGCBLD0xzrcsOjsukpn/L26FHQf751CGSq03bt?= =?us-ascii?Q?c5zsQlsHAgRVVuWpbncSbLdS32mZzn0v5K6F49zYkuNL9GzneDzoVtG1IKWq?= =?us-ascii?Q?oMhq9xMryhhz6YJZlmAl0N03T/ZHXOSGLzlkLnp1ikPWkLjWzQIVavjg1b1O?= =?us-ascii?Q?dzgdNCQtqIyX+oLvUNPT36ankqW7a4HeYAco4RXyl9wSDSOZiZ225O3WAElv?= =?us-ascii?Q?jRegnYK/245SpXnkMWylGg1Tv3IGYP+L/JdWpoWKW9ILLaMM1GP3NrUjVrYy?= =?us-ascii?Q?UJRndMiobZTu2G2bh1B7EbZyLceqSoSgtstLwI49l1x149PKfKTk0kvCHPER?= =?us-ascii?Q?xrTKc3Y65krIgxPdLMNAWk7vVxJvT+/wivH1/46pA78Vo7T9hqpXbjtp7EQI?= =?us-ascii?Q?bEJZJhyjQulUjQmVzTU5UgnMaITr0z51pRNHRyU15VZ2lmeEyVe8u3g3+9RC?= =?us-ascii?Q?rpQZ+wSyHL9JgQkRZokvbhRgqoR4mrWvxgY+SUSkZL17+RTwFqj3UyGxDFJh?= =?us-ascii?Q?y58sSIa0t2Mx+7PpOehrwdacCuQUUlBBLZvPVI72N5gXKdjXItdVXgcn54zh?= =?us-ascii?Q?Es1GUrud8+FLxP269f3I0NskU4Cs0YUzBKVXS0NYV/PV+AiH6ESYOR/kWa00?= =?us-ascii?Q?D2nYI1V00MLJnZoX9E8Pjax8QaN6LC3StgaaSvVH1Zu4aroWKBrJleI4qgk2?= =?us-ascii?Q?RCPOcG3Y7Q=3D=3D?= X-OriginatorOrg: atomlin.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5f4ed5c2-ad4e-414e-0205-08deffc5bbe7 X-MS-Exchange-CrossTenant-AuthSource: CWLP123MB6607.GBRP123.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Aug 2026 20:49:46.0907 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: e6a32402-7d7b-4830-9a2b-76945bbbcb57 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 4jV4FIh6wGSMi5cfWR8Xr9ymB5MS7xnArIAdzy5epKluc185T827KLOZhRZqnEXYOYbF+DxTAgdvVyonb0Q7uA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LO2P123MB6104 When BTF (BPF Type Format) metadata is loaded from vmlinux, 'perf trace' can inspect the precise C types of tracepoint and system call parameters. However, function pointer arguments are currently not recognised during BTF pretty-printing and default to hexadecimal output. Introduce btf_is_func_ptr() to inspect BTF type hierarchies (i.e., traversing pointers, typedefs, and type modifiers) to determine whether a parameter resolves to a function prototype (BTF_KIND_FUNC_PROTO). Generalise BTF type caching via syscall_arg_fmt__cache_btf_type() to handle structs, unions, enums, and function pointers alike. When a field is identified as a kernel function pointer, trace__btf_scnprintf() routes its value to syscall_arg__scnprintf_ksym(), enabling automatic zero-config symbolisation of kernel function pointers whenever BTF is available. Signed-off-by: Aaron Tomlin --- tools/perf/builtin-trace.c | 100 ++++++++++++++++++++++++++++--------- 1 file changed, 77 insertions(+), 23 deletions(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 0a12d7b37d8d..9f9494f9d9d8 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -122,6 +122,7 @@ struct syscall_arg_fmt { #ifdef HAVE_LIBBPF_SUPPORT const struct btf_type *type; int type_id; /* used in btf_dump */ + bool btf_type_cached; #endif }; @@ -979,21 +980,61 @@ static size_t syscall_arg__scnprintf_getrandom_flags(char *bf, size_t size, #define SCA_GETRANDOM_FLAGS syscall_arg__scnprintf_getrandom_flags #ifdef HAVE_LIBBPF_SUPPORT -static void syscall_arg_fmt__cache_btf_enum(struct syscall_arg_fmt *arg_fmt, struct btf *btf, char *type) +static bool btf_is_func_ptr(const struct btf *btf, const struct btf_type *type) { + while (type) { + if (btf_is_ptr(type) || btf_is_typedef(type) || btf_is_mod(type)) + type = btf__type_by_id(btf, type->type); + else + break; + } + return type && btf_is_func_proto(type); +} + +static void syscall_arg_fmt__cache_btf_type(struct syscall_arg_fmt *arg_fmt, + struct btf *btf, const char *type) +{ + char name[128]; + const char *pos; + size_t len = 0; int id; - type = strstr(type, "enum "); + arg_fmt->btf_type_cached = true; + if (type == NULL) return; - type += 5; // skip "enum " to get the enumeration name + /* Pointers to enums are memory addresses, not scalar enums */ + if (strstr(type, "enum ") && strchr(type, '*')) + return; + + if ((pos = strstr(type, "enum ")) != NULL) + pos += 5; + else if ((pos = strstr(type, "struct ")) != NULL) + pos += 7; + else if ((pos = strstr(type, "union ")) != NULL) + pos += 6; + else + pos = type; + + while (isspace(*pos)) + pos++; + + while ((isalnum(pos[len]) || pos[len] == '_') && len < sizeof(name) - 1) { + name[len] = pos[len]; + len++; + } + name[len] = '\0'; - id = btf__find_by_name(btf, type); + if (len == 0) + return; + + id = btf__find_by_name(btf, name); if (id < 0) return; arg_fmt->type = btf__type_by_id(btf, id); + arg_fmt->type_id = id; } static bool syscall_arg__strtoul_btf_enum(char *bf, size_t size, struct syscall_arg *arg, u64 *val) @@ -1027,10 +1068,8 @@ static bool syscall_arg__strtoul_btf_type(char *bf, size_t size, struct syscall_ if (btf == NULL) return false; - if (arg->fmt->type == NULL) { - // See if this is an enum - syscall_arg_fmt__cache_btf_enum(arg->fmt, btf, type); - } + if (!arg->fmt->btf_type_cached) + syscall_arg_fmt__cache_btf_type(arg->fmt, btf, type); // Now let's see if we have a BTF type resolved bt = arg->fmt->type; @@ -1038,19 +1077,22 @@ static bool syscall_arg__strtoul_btf_type(char *bf, size_t size, struct syscall_ return false; // If it is an enum: - if (btf_is_enum(arg->fmt->type)) + if (btf_is_enum(arg->fmt->type)) { + if (type && strchr(type, '*')) + return false; return syscall_arg__strtoul_btf_enum(bf, size, arg, val); + } return false; } -static size_t btf_enum_scnprintf(const struct btf_type *type, struct btf *btf, char *bf, size_t size, int val) +static size_t btf_enum_scnprintf(const struct btf_type *type, struct btf *btf, char *bf, size_t size, unsigned long val) { struct btf_enum *be = btf_enum(type); const unsigned int nr_entries = btf_vlen(type); for (unsigned int i = 0; i < nr_entries; ++i, ++be) { - if (be->val == val) { + if ((unsigned long)(__u32)be->val == val || (unsigned long)be->val == val) { return scnprintf(bf, size, "%s", btf__name_by_offset(btf, be->name_off)); } @@ -1077,14 +1119,19 @@ static size_t btf_struct_scnprintf(const struct btf_type *type, struct btf *btf, .bf = bf, .size = size, }; - struct augmented_arg *augmented_arg = arg->augmented.args; + struct augmented_arg *augmented_arg; int type_id = arg->fmt->type_id, consumed; struct btf_dump *btf_dump; LIBBPF_OPTS(btf_dump_opts, dump_opts); LIBBPF_OPTS(btf_dump_type_data_opts, dump_data_opts); - if (arg == NULL || arg->augmented.args == NULL) + if (arg == NULL || arg->augmented.args == NULL || arg->augmented.size <= 0 || + arg->fmt == NULL || !arg->fmt->from_user) + return 0; + + augmented_arg = arg->augmented.args; + if (augmented_arg->size <= 0) return 0; dump_data_opts.compact = true; @@ -1095,8 +1142,10 @@ static size_t btf_struct_scnprintf(const struct btf_type *type, struct btf *btf, return 0; /* pretty print the struct data here */ - if (btf_dump__dump_type_data(btf_dump, type_id, arg->augmented.args->value, type->size, &dump_data_opts) == 0) + if (btf_dump__dump_type_data(btf_dump, type_id, augmented_arg->value, type->size, &dump_data_opts) == 0) { + btf_dump__free(btf_dump); return 0; + } consumed = sizeof(*augmented_arg) + augmented_arg->size; arg->augmented.args = ((void *)arg->augmented.args) + consumed; @@ -1108,33 +1157,37 @@ static size_t btf_struct_scnprintf(const struct btf_type *type, struct btf *btf, } static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg *arg, char *bf, - size_t size, int val, char *type) + size_t size, unsigned long val, char *type) { struct syscall_arg_fmt *arg_fmt = arg->fmt; if (trace->btf == NULL) return 0; - if (arg_fmt->type == NULL) { - // Check if this is an enum and if we have the BTF type for it. - syscall_arg_fmt__cache_btf_enum(arg_fmt, trace->btf, type); - } + if (!arg_fmt->btf_type_cached) + syscall_arg_fmt__cache_btf_type(arg_fmt, trace->btf, type); // Did we manage to find a BTF type for the syscall/tracepoint argument? if (arg_fmt->type == NULL) return 0; - if (btf_is_enum(arg_fmt->type)) + if (btf_is_enum(arg_fmt->type)) { + if (type && strchr(type, '*')) + return 0; return btf_enum_scnprintf(arg_fmt->type, trace->btf, bf, size, val); - else if (btf_is_struct(arg_fmt->type) || btf_is_union(arg_fmt->type)) + } else if (btf_is_struct(arg_fmt->type) || btf_is_union(arg_fmt->type)) return btf_struct_scnprintf(arg_fmt->type, trace->btf, bf, size, arg); + else if (btf_is_func_ptr(trace->btf, arg_fmt->type)) { + arg->val = val; + return syscall_arg__scnprintf_ksym(bf, size, arg); + } return 0; } #else // HAVE_LIBBPF_SUPPORT static size_t trace__btf_scnprintf(struct trace *trace __maybe_unused, struct syscall_arg *arg __maybe_unused, - char *bf __maybe_unused, size_t size __maybe_unused, int val __maybe_unused, + char *bf __maybe_unused, size_t size __maybe_unused, unsigned long val __maybe_unused, char *type __maybe_unused) { return 0; @@ -2579,7 +2632,8 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size, default_scnprintf = sc->arg_fmt[arg.idx].scnprintf; - if (trace->force_btf || default_scnprintf == NULL || default_scnprintf == SCA_PTR) { + if (trace->force_btf || default_scnprintf == NULL || + default_scnprintf == SCA_PTR || default_scnprintf == SCA_KSYM) { btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed, size - printed, val, field->type); if (btf_printed) { -- 2.55.0