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 CF28CC433EF for ; Mon, 18 Apr 2022 13:09:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232643AbiDRNMC (ORCPT ); Mon, 18 Apr 2022 09:12:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243231AbiDRNJ6 (ORCPT ); Mon, 18 Apr 2022 09:09:58 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2770637A07; Mon, 18 Apr 2022 05:49:24 -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 91DA2B80EE7; Mon, 18 Apr 2022 12:49:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C345BC385A1; Mon, 18 Apr 2022 12:49:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1650286148; bh=wT4/WeIwjYBzff+W5ZOYqpym7Y597fnbp/CAYefVOIE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sgjn8gsRszB6q4ey1OP/i5SzwAo5b60Dtcb7gpMpCZZV82QYAPyEcXKZZjZK9rlgV K+fUMDnTzqiaFrYyAQujbrgYQEbGEL5zcUuPsVq8jILIGkxMThZ7smJUyZk0nRWBbP S/8NhCSCWiDX3AEzy/gNF0Sssb4JXfkNT3QxVcNuSXp0rJ00pl9+6bO1qreOrUlvtu AO5dCuXrj+yCkWKa6wPqmi0shzqXCycS76wM/mni9vqxhF/NgjuFFOTlLtw3vRLa3r z8fngrW8+fpq823RjavNKC0GzI2nNryfYc5zP+3DeAg0GixTPx3UOou6Av3SN6G6AN f+fU2Ns2C7FVA== From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Masami Hiramatsu Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, lkml , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh Subject: [PATCHv2 bpf-next 3/4] bpf: Resolve symbols with kallsyms_lookup_names for kprobe multi link Date: Mon, 18 Apr 2022 14:48:33 +0200 Message-Id: <20220418124834.829064-4-jolsa@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220418124834.829064-1-jolsa@kernel.org> References: <20220418124834.829064-1-jolsa@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Using kallsyms_lookup_names function to speed up symbols lookup in kprobe multi link attachment and replacing with it the current kprobe_multi_resolve_syms function. This speeds up bpftrace kprobe attachment: # perf stat -r 5 -e cycles ./src/bpftrace -e 'kprobe:x* { } i:ms:1 { exit(); }' ... 6.5681 +- 0.0225 seconds time elapsed ( +- 0.34% ) After: # perf stat -r 5 -e cycles ./src/bpftrace -e 'kprobe:x* { } i:ms:1 { exit(); }' ... 0.5661 +- 0.0275 seconds time elapsed ( +- 4.85% ) Signed-off-by: Jiri Olsa --- kernel/trace/bpf_trace.c | 113 +++++++++++++++++++++++---------------- 1 file changed, 67 insertions(+), 46 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index b26f3da943de..f49cdc46a21f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2226,6 +2226,60 @@ struct bpf_kprobe_multi_run_ctx { unsigned long entry_ip; }; +struct user_syms { + const char **syms; + char *buf; +}; + +static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32 cnt) +{ + unsigned long __user usymbol; + const char **syms = NULL; + char *buf = NULL, *p; + int err = -EFAULT; + unsigned int i; + + err = -ENOMEM; + syms = kvmalloc(cnt * sizeof(*syms), GFP_KERNEL); + if (!syms) + goto error; + + buf = kvmalloc(cnt * KSYM_NAME_LEN, GFP_KERNEL); + if (!buf) + goto error; + + for (p = buf, i = 0; i < cnt; i++) { + if (__get_user(usymbol, usyms + i)) { + err = -EFAULT; + goto error; + } + err = strncpy_from_user(p, (const char __user *) usymbol, KSYM_NAME_LEN); + if (err == KSYM_NAME_LEN) + err = -E2BIG; + if (err < 0) + goto error; + syms[i] = p; + p += err + 1; + } + + err = 0; + us->syms = syms; + us->buf = buf; + +error: + if (err) { + kvfree(syms); + kvfree(buf); + } + return err; +} + +static void free_user_syms(struct user_syms *us) +{ + kvfree(us->syms); + kvfree(us->buf); +} + static void bpf_kprobe_multi_link_release(struct bpf_link *link) { struct bpf_kprobe_multi_link *kmulti_link; @@ -2346,53 +2400,12 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long entry_ip, kprobe_multi_link_prog_run(link, entry_ip, regs); } -static int -kprobe_multi_resolve_syms(const void __user *usyms, u32 cnt, - unsigned long *addrs) +static int symbols_cmp(const void *a, const void *b) { - unsigned long addr, size; - const char __user **syms; - int err = -ENOMEM; - unsigned int i; - char *func; - - size = cnt * sizeof(*syms); - syms = kvzalloc(size, GFP_KERNEL); - if (!syms) - return -ENOMEM; - - func = kmalloc(KSYM_NAME_LEN, GFP_KERNEL); - if (!func) - goto error; - - if (copy_from_user(syms, usyms, size)) { - err = -EFAULT; - goto error; - } - - for (i = 0; i < cnt; i++) { - err = strncpy_from_user(func, syms[i], KSYM_NAME_LEN); - if (err == KSYM_NAME_LEN) - err = -E2BIG; - if (err < 0) - goto error; - err = -EINVAL; - addr = kallsyms_lookup_name(func); - if (!addr) - goto error; - if (!kallsyms_lookup_size_offset(addr, &size, NULL)) - goto error; - addr = ftrace_location_range(addr, addr + size - 1); - if (!addr) - goto error; - addrs[i] = addr; - } + const char **str_a = (const char **) a; + const char **str_b = (const char **) b; - err = 0; -error: - kvfree(syms); - kfree(func); - return err; + return strcmp(*str_a, *str_b); } int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) @@ -2438,7 +2451,15 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error; } } else { - err = kprobe_multi_resolve_syms(usyms, cnt, addrs); + struct user_syms us; + + err = copy_user_syms(&us, usyms, cnt); + if (err) + goto error; + + sort(us.syms, cnt, sizeof(*us.syms), symbols_cmp, NULL); + err = kallsyms_lookup_names(us.syms, cnt, addrs); + free_user_syms(&us); if (err) goto error; } -- 2.35.1