From patchwork Fri Jun 14 08:19:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Berg X-Patchwork-Id: 13698174 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (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 9693F1836F6; Fri, 14 Jun 2024 08:20:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718353204; cv=none; b=tUu8XInMdoTpzd8MbKITh7Ix1hPtOzAj3QuDLPMez6Rs8PdrDDiWzLQrgOmHAfPOw3aSb4jtued+pQ6cXWoFYIHOcxQzpFX1QediEuMvvQJ0sOBz84DuhS1itK3zjPmJ3qrjs6/kWazYvaMfbCsp8DnU9wcm4gxtl90+Czl+2ZA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718353204; c=relaxed/simple; bh=9oKO2D4zWCKhI2VBtR/81yIv1tk+S12ZDw4TjMZsTgE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tNLXHKmYFPfym27xY46tNPcuAZPihVbma+t9ifzt9X+EVtmp5ztjtdZDkiVNFMpzH5JrIIELxXvLnznFZ+QmhyavmJezZBR/dgli3BB6C9v6y0yJ6Ix4Pas9R6al2nMiDV4FOHO5CBCnPJXV9ENZdt4R59eMXEsT3VJJ3DHfckg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=OmYQWXR0; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="OmYQWXR0" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Content-Type:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=mUKYbzIsaWUiVGPBFM6gg/YVA4pBqjkVCzwArhT6VzE=; t=1718353202; x=1719562802; b=OmYQWXR0xwBIr0gC727gvrnt/ibwe9LdJIW4F/3RIhb6DBY qswYA+z1/dc3MBxNmL3LlXZCOat4R/cDQzM1yb7JgxdJU7GLvjIIBa/mASs55ODN05DTIHGPQDseD bA9DHJ34RMPQED1aQGHr/GsyWj85YtwgEjrKKRkVRzfdBOrNCGmNG1d7F2+qYKDMCnbGrALHQM3r7 xkvFskGBgaeEWGvZTgNc78Bpm1ZFLCqYcR+00+jFx4oCLRRM3DQG23NEEbxCORjYCMV4gpyQDyRat Hlx7s6TTNE8xGYGC2eE/8pdbXgqYHPPq45vHW2BT5ckSEZSyto4JUQ2PjxqQullw==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.97) (envelope-from ) id 1sI2AB-0000000DZpq-23PY; Fri, 14 Jun 2024 10:19:59 +0200 From: Johannes Berg To: linux-kernel@vger.kernel.org Cc: linux-trace-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Johannes Berg Subject: [PATCH v5 1/4] tracing: add __print_sym() to replace __print_symbolic() Date: Fri, 14 Jun 2024 10:19:13 +0200 Message-ID: <20240614101956.1328f394f6be.I4d4d01236eaa9553d91dc4fd5d6bd8dd9dbc8bf2@changeid> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240614081956.19832-6-johannes@sipsolutions.net> References: <20240614081956.19832-6-johannes@sipsolutions.net> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Johannes Berg The way __print_symbolic() works is limited and inefficient in multiple ways: - you can only use it with a static list of symbols, but e.g. the SKB dropreasons are now a dynamic list - it builds the list in memory _three_ times, so it takes a lot of memory: - The print_fmt contains the list (since it's passed to the macro there). This actually contains the names _twice_, which is fixed up at runtime. - TRACE_DEFINE_ENUM() puts a 24-byte struct trace_eval_map for every entry, plus the string pointed to by it, which cannot be deduplicated with the strings in the print_fmt - The in-kernel symbolic printing creates yet another list of struct trace_print_flags for trace_print_symbols_seq() - it also requires runtime fixup during init, which is a lot of string parsing due to the print_fmt fixup Introduce __print_sym() to - over time - replace the old one. We can easily extend this also to __print_flags later, but I cared only about the SKB dropreasons for now, which has only __print_symbolic(). This new __print_sym() requires only a single list of items, created by TRACE_DEFINE_SYM_LIST(), or can even use another already existing list by using TRACE_DEFINE_SYM_FNS() with lookup and show methods. Then, instead of doing an init-time fixup, just do this at the time when userspace reads the print_fmt. This way, dynamically updated lists are possible. For userspace, nothing actually changes, because the print_fmt is shown exactly the same way the old __print_symbolic() was. This adds about 4k .text in my test builds, but that'll be more than paid for by the actual conversions. Signed-off-by: Johannes Berg --- v2: - fix RCU - use ':' as separator to simplify the code, that's still not valid in a C identifier v3: - add missing #undef lines (reported by Simon Horman) - clarify name is not NUL-terminated and fix logic for the comparison for that v4: - fix non-modular builds and handle TRACE_EVENT_FL_DYNAMIC v5: - fix build warning in non-modular build --- include/asm-generic/vmlinux.lds.h | 3 +- include/linux/module.h | 2 + include/linux/trace_events.h | 7 ++ include/linux/tracepoint.h | 20 +++++ include/trace/stages/init.h | 55 ++++++++++++ include/trace/stages/stage2_data_offsets.h | 6 ++ include/trace/stages/stage3_trace_output.h | 9 ++ include/trace/stages/stage7_class_define.h | 3 + kernel/module/main.c | 3 + kernel/trace/trace_events.c | 99 +++++++++++++++++++++- kernel/trace/trace_output.c | 45 ++++++++++ 11 files changed, 249 insertions(+), 3 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 5703526d6ebf..8275a06bcaee 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -258,7 +258,8 @@ #define FTRACE_EVENTS() \ . = ALIGN(8); \ BOUNDED_SECTION(_ftrace_events) \ - BOUNDED_SECTION_BY(_ftrace_eval_map, _ftrace_eval_maps) + BOUNDED_SECTION_BY(_ftrace_eval_map, _ftrace_eval_maps) \ + BOUNDED_SECTION(_ftrace_sym_defs) #else #define FTRACE_EVENTS() #endif diff --git a/include/linux/module.h b/include/linux/module.h index ffa1c603163c..7256762d59e1 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -524,6 +524,8 @@ struct module { unsigned int num_trace_events; struct trace_eval_map **trace_evals; unsigned int num_trace_evals; + struct trace_sym_def **trace_sym_defs; + unsigned int num_trace_sym_defs; #endif #ifdef CONFIG_FTRACE_MCOUNT_RECORD unsigned int num_ftrace_callsites; diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 9df3e2973626..2743280c9a46 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -27,6 +27,13 @@ const char *trace_print_flags_seq(struct trace_seq *p, const char *delim, const char *trace_print_symbols_seq(struct trace_seq *p, unsigned long val, const struct trace_print_flags *symbol_array); +const char *trace_print_sym_seq(struct trace_seq *p, unsigned long long val, + const char *(*lookup)(unsigned long long val)); +const char *trace_sym_lookup(const struct trace_sym_entry *list, + size_t len, unsigned long long value); +void trace_sym_show(struct seq_file *m, + const struct trace_sym_entry *list, size_t len); + #if BITS_PER_LONG == 32 const char *trace_print_flags_seq_u64(struct trace_seq *p, const char *delim, unsigned long long flags, diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 689b6d71590e..cc3b387953d1 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -31,6 +31,24 @@ struct trace_eval_map { unsigned long eval_value; }; +struct trace_sym_def { + const char *system; + const char *symbol_id; + /* may return NULL, called under rcu_read_lock() */ + const char * (*lookup)(unsigned long long); + /* + * Must print the list: ', { val, "name"}, ...' + * with no trailing comma, but with the leading ', ' + * to simplify things: + */ + void (*show)(struct seq_file *); +}; + +struct trace_sym_entry { + unsigned long long value; + const char *name; +}; + #define TRACEPOINT_DEFAULT_PRIO 10 extern struct srcu_struct tracepoint_srcu; @@ -109,6 +127,8 @@ extern void syscall_unregfunc(void); #define TRACE_DEFINE_ENUM(x) #define TRACE_DEFINE_SIZEOF(x) +#define TRACE_DEFINE_SYM_FNS(...) +#define TRACE_DEFINE_SYM_LIST(...) #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) diff --git a/include/trace/stages/init.h b/include/trace/stages/init.h index 000bcfc8dd2e..ef63ab64250d 100644 --- a/include/trace/stages/init.h +++ b/include/trace/stages/init.h @@ -23,6 +23,61 @@ TRACE_MAKE_SYSTEM_STR(); __section("_ftrace_eval_map") \ *TRACE_SYSTEM##_##a = &__##TRACE_SYSTEM##_##a +/* + * Define a symbol for __print_sym by giving lookup and + * show functions. See &struct trace_sym_def. + */ +#undef TRACE_DEFINE_SYM_FNS +#define TRACE_DEFINE_SYM_FNS(_symbol_id, _lookup, _show) \ + _TRACE_DEFINE_SYM_FNS(TRACE_SYSTEM, _symbol_id, _lookup, _show) +#define _TRACE_DEFINE_SYM_FNS(_system, _symbol_id, _lookup, _show) \ + __TRACE_DEFINE_SYM_FNS(_system, _symbol_id, _lookup, _show) +#define __TRACE_DEFINE_SYM_FNS(_system, _symbol_id, _lookup, _show) \ + ___TRACE_DEFINE_SYM_FNS(_system ## _ ## _symbol_id, _symbol_id, \ + _lookup, _show) +#define ___TRACE_DEFINE_SYM_FNS(_name, _symbol_id, _lookup, _show) \ + static struct trace_sym_def \ + __trace_sym_def_ ## _name = { \ + .system = TRACE_SYSTEM_STRING, \ + .symbol_id = #_symbol_id, \ + .lookup = _lookup, \ + .show = _show, \ + }; \ + static struct trace_sym_def \ + __section("_ftrace_sym_defs") \ + *__trace_sym_def_p_ ## _name = &__trace_sym_def_ ## _name + +/* + * Define a symbol for __print_sym by giving lookup and + * show functions. See &struct trace_sym_def. + */ +#undef TRACE_DEFINE_SYM_LIST +#define TRACE_DEFINE_SYM_LIST(_symbol_id, ...) \ + _TRACE_DEFINE_SYM_LIST(TRACE_SYSTEM, _symbol_id, __VA_ARGS__) +#define _TRACE_DEFINE_SYM_LIST(_system, _symbol_id, ...) \ + __TRACE_DEFINE_SYM_LIST(_system, _symbol_id, __VA_ARGS__) +#define __TRACE_DEFINE_SYM_LIST(_system, _symbol_id, ...) \ + ___TRACE_DEFINE_SYM_LIST(_system ## _ ## _symbol_id, _symbol_id,\ + __VA_ARGS__) +#define ___TRACE_DEFINE_SYM_LIST(_name, _symbol_id, ...) \ + static struct trace_sym_entry \ + __trace_sym_list_ ## _name[] = { __VA_ARGS__ }; \ + static const char * \ + __trace_sym_lookup_ ## _name(unsigned long long value) \ + { \ + return trace_sym_lookup(__trace_sym_list_ ## _name, \ + ARRAY_SIZE(__trace_sym_list_ ## _name), value); \ + } \ + static void \ + __trace_sym_show_ ## _name(struct seq_file *m) \ + { \ + trace_sym_show(m, __trace_sym_list_ ## _name, \ + ARRAY_SIZE(__trace_sym_list_ ## _name)); \ + } \ + ___TRACE_DEFINE_SYM_FNS(_name, _symbol_id, \ + __trace_sym_lookup_ ## _name, \ + __trace_sym_show_ ## _name) + #undef TRACE_DEFINE_SIZEOF #define TRACE_DEFINE_SIZEOF(a) \ static struct trace_eval_map __used __initdata \ diff --git a/include/trace/stages/stage2_data_offsets.h b/include/trace/stages/stage2_data_offsets.h index 8b0cff06d346..5afd9de7deb3 100644 --- a/include/trace/stages/stage2_data_offsets.h +++ b/include/trace/stages/stage2_data_offsets.h @@ -5,6 +5,12 @@ #undef TRACE_DEFINE_ENUM #define TRACE_DEFINE_ENUM(a) +#undef TRACE_DEFINE_SYM_FNS +#define TRACE_DEFINE_SYM_FNS(_symbol_id, _lookup, _show) + +#undef TRACE_DEFINE_SYM_LIST +#define TRACE_DEFINE_SYM_LIST(_symbol_id, ...) + #undef TRACE_DEFINE_SIZEOF #define TRACE_DEFINE_SIZEOF(a) diff --git a/include/trace/stages/stage3_trace_output.h b/include/trace/stages/stage3_trace_output.h index c1fb1355d309..d2c6458b62dc 100644 --- a/include/trace/stages/stage3_trace_output.h +++ b/include/trace/stages/stage3_trace_output.h @@ -79,6 +79,15 @@ trace_print_symbols_seq(p, value, symbols); \ }) +#undef __print_sym +#define __print_sym(value, symbol_id) \ + ___print_sym(TRACE_SYSTEM, value, symbol_id) +#define ___print_sym(sys, value, symbol_id) \ + ____print_sym(sys, value, symbol_id) +#define ____print_sym(sys, value, symbol_id) \ + trace_print_sym_seq(p, value, \ + __trace_sym_def_p_ ## sys ## _ ## symbol_id->lookup) + #undef __print_flags_u64 #undef __print_symbolic_u64 #if BITS_PER_LONG == 32 diff --git a/include/trace/stages/stage7_class_define.h b/include/trace/stages/stage7_class_define.h index bcb960d16fc0..cf552916935f 100644 --- a/include/trace/stages/stage7_class_define.h +++ b/include/trace/stages/stage7_class_define.h @@ -25,6 +25,9 @@ #undef __print_hex_dump #undef __get_buf +#undef __print_sym +#define __print_sym(value, symbol_id) __print_sym(value:symbol_id) + /* * The below is not executed in the kernel. It is only what is * displayed in the print format for userspace to parse. diff --git a/kernel/module/main.c b/kernel/module/main.c index d18a94b973e1..5b1700b56a06 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2179,6 +2179,9 @@ static int find_module_sections(struct module *mod, struct load_info *info) mod->trace_evals = section_objs(info, "_ftrace_eval_map", sizeof(*mod->trace_evals), &mod->num_trace_evals); + mod->trace_sym_defs = section_objs(info, "_ftrace_sym_defs", + sizeof(*mod->trace_sym_defs), + &mod->num_trace_sym_defs); #endif #ifdef CONFIG_TRACING mod->trace_bprintk_fmt_start = section_objs(info, "__trace_printk_fmt", diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 6ef29eba90ce..0859e879ff09 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1570,6 +1570,102 @@ static void *f_next(struct seq_file *m, void *v, loff_t *pos) return node; } +extern struct trace_sym_def *__start_ftrace_sym_defs[]; +extern struct trace_sym_def *__stop_ftrace_sym_defs[]; + +/* note: @name is not NUL-terminated */ +static void show_sym_list(struct seq_file *m, struct trace_event_call *call, + const char *name, unsigned int name_len) +{ + struct trace_sym_def **sym_defs; + unsigned int n_sym_defs, i; + + if ((call->flags & TRACE_EVENT_FL_DYNAMIC) || !call->module) { + sym_defs = __start_ftrace_sym_defs; + n_sym_defs = __stop_ftrace_sym_defs - __start_ftrace_sym_defs; + } else { +#ifdef CONFIG_MODULES + struct module *mod = call->module; + + sym_defs = mod->trace_sym_defs; + n_sym_defs = mod->num_trace_sym_defs; +#else + return; +#endif /* CONFIG_MODULES */ + } + + for (i = 0; i < n_sym_defs; i++) { + unsigned int sym_len; + + if (!sym_defs[i]) + continue; + if (sym_defs[i]->system != call->class->system) + continue; + sym_len = strlen(sym_defs[i]->symbol_id); + if (name_len != sym_len) + continue; + if (strncmp(sym_defs[i]->symbol_id, name, sym_len)) + continue; + if (sym_defs[i]->show) + sym_defs[i]->show(m); + break; + } +} + +static void show_print_fmt(struct seq_file *m, struct trace_event_call *call) +{ + char *ptr = call->print_fmt; + bool in_print_sym = false; + int quote = 0; + + seq_puts(m, "\nprint fmt: "); + while (*ptr) { + if (*ptr == '\\') { + seq_putc(m, *ptr); + ptr++; + /* paranoid */ + if (!*ptr) + break; + goto next; + } + if (*ptr == '"') { + quote ^= 1; + goto next; + } + if (quote) + goto next; + + if (in_print_sym && *ptr != ':') + goto next; + + if (in_print_sym && *ptr == ':') { + const char *name; + + ptr++; + name = ptr; + /* skip the name */ + while (*ptr && *ptr != ')') + ptr++; + /* and show the actual list inline now */ + show_sym_list(m, call, name, ptr - name); + in_print_sym = false; + continue; + } + + if (strncmp(ptr, "__print_sym(", 12) == 0) { + ptr += 12; + seq_puts(m, "__print_symbolic("); + in_print_sym = true; + continue; + } +next: + seq_putc(m, *ptr); + ptr++; + } + + seq_putc(m, '\n'); +} + static int f_show(struct seq_file *m, void *v) { struct trace_event_call *call = event_file_data(m->private); @@ -1588,8 +1684,7 @@ static int f_show(struct seq_file *m, void *v) return 0; case FORMAT_PRINTFMT: - seq_printf(m, "\nprint fmt: %s\n", - call->print_fmt); + show_print_fmt(m, call); return 0; } diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index d8b302d01083..8a3aa661ea46 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -124,6 +124,51 @@ trace_print_symbols_seq(struct trace_seq *p, unsigned long val, } EXPORT_SYMBOL(trace_print_symbols_seq); +const char *trace_sym_lookup(const struct trace_sym_entry *list, + size_t len, unsigned long long value) +{ + size_t i; + + for (i = 0; i < len; i++) { + if (list[i].value == value) + return list[i].name; + } + return NULL; +} +EXPORT_SYMBOL(trace_sym_lookup); + +void trace_sym_show(struct seq_file *m, + const struct trace_sym_entry *list, size_t len) +{ + size_t i; + + for (i = 0; i < len; i++) + seq_printf(m, ", { %lld, \"%s\" }", + list[i].value, list[i].name); +} +EXPORT_SYMBOL(trace_sym_show); + +const char * +trace_print_sym_seq(struct trace_seq *p, unsigned long long val, + const char *(*lookup)(unsigned long long val)) +{ + const char *ret = trace_seq_buffer_ptr(p); + const char *name; + + rcu_read_lock(); + name = lookup(val); + if (name) + trace_seq_puts(p, name); + else + trace_seq_printf(p, "0x%llx", val); + rcu_read_unlock(); + + trace_seq_putc(p, 0); + + return ret; +} +EXPORT_SYMBOL(trace_print_sym_seq); + #if BITS_PER_LONG == 32 const char * trace_print_flags_seq_u64(struct trace_seq *p, const char *delim,