From mboxrd@z Thu Jan 1 00:00:00 1970 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 CDF2CC433F5 for ; Fri, 29 Apr 2022 14:56:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378066AbiD2O7m (ORCPT ); Fri, 29 Apr 2022 10:59:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378055AbiD2O7i (ORCPT ); Fri, 29 Apr 2022 10:59:38 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46AFFAF1F1; Fri, 29 Apr 2022 07:56:19 -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 ams.source.kernel.org (Postfix) with ESMTPS id F1205B835DF; Fri, 29 Apr 2022 14:56:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FAB9C385A7; Fri, 29 Apr 2022 14:56:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651244176; bh=55dPsFKyaJHm2X36nyJJ6CyaTJGEyAtYgXfkNvY8120=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nYb27mqCCvMQYHhGuOJj/ESE9vTGSFM+TWDg6GxTzLLlzjUAcKNQ4B7zCc8+g3ffM q2SbAWlAnpje85wpNKgGQOJc9PB3o2WOLoJPeM7YaRgh3RmAHfTSOQ3Cra7lvB0x3O doOHu9cyTZy2rMF9rvwNA/Wk5aYxXfZFFa1QWNE3uu4qxU7Tap20xm1wJZN29HKg4/ RfEG+xgerU6YkR7qZePkRPXZy9rDhLJ2AS2tQmM5j+h3JwxotqtCgJNUaiNmc3M7hP V7LkhYvwWcUTysu6cUX+gZ+N+amu9Mc2eQAtO/l1p51cT2NaBB8R+I30XCSsNRL9kq 593RlzeNYOtCQ== Date: Fri, 29 Apr 2022 23:56:11 +0900 From: Masami Hiramatsu To: Jiri Olsa Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , netdev@vger.kernel.org, bpf@vger.kernel.org, lkml , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Steven Rostedt Subject: Re: [PATCHv4 bpf-next 2/5] ftrace: Add ftrace_lookup_symbols function Message-Id: <20220429235611.4d14d87efc0b6189dadfe3b1@kernel.org> In-Reply-To: <20220428201207.954552-3-jolsa@kernel.org> References: <20220428201207.954552-1-jolsa@kernel.org> <20220428201207.954552-3-jolsa@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 28 Apr 2022 22:12:04 +0200 Jiri Olsa wrote: > Adding ftrace_lookup_symbols function that resolves array of symbols > with single pass over kallsyms. > > The user provides array of string pointers with count and pointer to > allocated array for resolved values. > > int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, > unsigned long *addrs) > > It iterates all kallsyms symbols and tries to loop up each in provided > symbols array with bsearch. The symbols array needs to be sorted by > name for this reason. > > We also check each symbol to pass ftrace_location, because this API > will be used for fprobe symbols resolving. This looks good to me. Reviewed-by: Masami Hiramatsu Thanks! > > Suggested-by: Andrii Nakryiko > Acked-by: Andrii Nakryiko > Signed-off-by: Jiri Olsa > --- > include/linux/ftrace.h | 6 ++++ > kernel/kallsyms.c | 1 + > kernel/trace/ftrace.c | 62 ++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 69 insertions(+) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 4816b7e11047..820500430eae 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -303,6 +303,8 @@ int unregister_ftrace_function(struct ftrace_ops *ops); > extern void ftrace_stub(unsigned long a0, unsigned long a1, > struct ftrace_ops *op, struct ftrace_regs *fregs); > > + > +int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *addrs); > #else /* !CONFIG_FUNCTION_TRACER */ > /* > * (un)register_ftrace_function must be a macro since the ops parameter > @@ -313,6 +315,10 @@ extern void ftrace_stub(unsigned long a0, unsigned long a1, > static inline void ftrace_kill(void) { } > static inline void ftrace_free_init_mem(void) { } > static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { } > +static inline int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *addrs) > +{ > + return -EOPNOTSUPP; > +} > #endif /* CONFIG_FUNCTION_TRACER */ > > struct ftrace_func_entry { > diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c > index fdfd308bebc4..fbdf8d3279ac 100644 > --- a/kernel/kallsyms.c > +++ b/kernel/kallsyms.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > > /* > * These will be re-linked against their real values > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 4f1d2f5e7263..07d87c7a525d 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -7964,3 +7964,65 @@ ftrace_enable_sysctl(struct ctl_table *table, int write, > mutex_unlock(&ftrace_lock); > return ret; > } > + > +static int symbols_cmp(const void *a, const void *b) > +{ > + const char **str_a = (const char **) a; > + const char **str_b = (const char **) b; > + > + return strcmp(*str_a, *str_b); > +} > + > +struct kallsyms_data { > + unsigned long *addrs; > + const char **syms; > + size_t cnt; > + size_t found; > +}; > + > +static int kallsyms_callback(void *data, const char *name, > + struct module *mod, unsigned long addr) > +{ > + struct kallsyms_data *args = data; > + > + if (!bsearch(&name, args->syms, args->cnt, sizeof(*args->syms), symbols_cmp)) > + return 0; > + > + addr = ftrace_location(addr); > + if (!addr) > + return 0; > + > + args->addrs[args->found++] = addr; > + return args->found == args->cnt ? 1 : 0; > +} > + > +/** > + * ftrace_lookup_symbols - Lookup addresses for array of symbols > + * > + * @sorted_syms: array of symbols pointers symbols to resolve, > + * must be alphabetically sorted > + * @cnt: number of symbols/addresses in @syms/@addrs arrays > + * @addrs: array for storing resulting addresses > + * > + * This function looks up addresses for array of symbols provided in > + * @syms array (must be alphabetically sorted) and stores them in > + * @addrs array, which needs to be big enough to store at least @cnt > + * addresses. > + * > + * This function returns 0 if all provided symbols are found, > + * -ESRCH otherwise. > + */ > +int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *addrs) > +{ > + struct kallsyms_data args; > + int err; > + > + args.addrs = addrs; > + args.syms = sorted_syms; > + args.cnt = cnt; > + args.found = 0; > + err = kallsyms_on_each_symbol(kallsyms_callback, &args); > + if (err < 0) > + return err; > + return args.found == args.cnt ? 0 : -ESRCH; > +} > -- > 2.35.1 > -- Masami Hiramatsu