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 E2541C3DA58 for ; Thu, 17 Aug 2023 18:26:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354342AbjHQSZn (ORCPT ); Thu, 17 Aug 2023 14:25:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354539AbjHQSZQ (ORCPT ); Thu, 17 Aug 2023 14:25:16 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F4113C11 for ; Thu, 17 Aug 2023 11:24:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EBB7464E97 for ; Thu, 17 Aug 2023 18:23:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FECEC433C7; Thu, 17 Aug 2023 18:23:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692296624; bh=f5ptGtZ/YpXtDqus4xfoEV65ews+Fja02Yil5w3snuA=; h=Date:From:To:Cc:Subject:From; b=ivwoZIfl3uUPq8IRMK8Ypt/YDj0SBGkEMppQln56UfPVMhvdwCoEj/F6dm96XQZm2 tjduUHGUljtnpuUM/hOHR4+R1u9K/g0BcSo0c8geobQjXI/9KIYyljRUcDobA+UpVL 69LeK0I4khQMuGnXwfYU3tyug3xjd3PHb4Ps5JSheLz0tjORPMNAOC/Kdv4kYGDXF6 XRDGpgqbMfx8PHnZDAFEUGg3Ul3iOo3FWrt3mcHC3sY/qBQixxKa8OWwB+u+Y5T94z xQQrtG21YnzXL4Ol0z4WUZJCJQNGuxojasThhmjagjACVWcgmy1ZeMG+if4DsriHiq nVoaW5HTsYdkQ== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 534B3404DF; Thu, 17 Aug 2023 15:23:41 -0300 (-03) Date: Thu, 17 Aug 2023 15:23:41 -0300 From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Adrian Hunter , Alan Maguire , Ian Rogers , Jiri Olsa , Linux Kernel Mailing List Subject: [PATCH 1/1] perf trace: Use heuristic when deciding if a syscall tracepoint "const char *" field is really a string Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 'perf trace' tries to find BPF progs associated with a syscall that have a signature that is similar to syscalls without one to try and reuse, so, for instance, the 'open' signature can be reused with many other syscalls that have as its first arg a string. It uses the tracefs events format file for finding a signature that can be reused, but then comes the "write" syscall with its second argument as a "const char *": # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_write/format name: sys_enter_write ID: 746 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:int __syscall_nr; offset:8; size:4; signed:1; field:unsigned int fd; offset:16; size:8; signed:0; field:const char * buf; offset:24; size:8; signed:0; field:size_t count; offset:32; size:8; signed:0; print fmt: "fd: 0x%08lx, buf: 0x%08lx, count: 0x%08lx", ((unsigned long)(REC->fd)), ((unsigned long)(REC->buf)), ((unsigned long)(REC->count)) # Which isn't a string (the man page for glibc has buf as "void *"), so we have to use the name of the argument as an heuristic, to consider a string just args that are "const char *" and that have in its name the "path", "file", etc substrings. With that now it reuses: [root@quaco ~]# perf trace -v --max-events=1 |& grep Reus Reusing "open" BPF sys_enter augmenter for "stat" Reusing "open" BPF sys_enter augmenter for "lstat" Reusing "open" BPF sys_enter augmenter for "access" Reusing "connect" BPF sys_enter augmenter for "accept" Reusing "sendto" BPF sys_enter augmenter for "recvfrom" Reusing "connect" BPF sys_enter augmenter for "bind" Reusing "connect" BPF sys_enter augmenter for "getsockname" Reusing "connect" BPF sys_enter augmenter for "getpeername" Reusing "open" BPF sys_enter augmenter for "execve" Reusing "open" BPF sys_enter augmenter for "truncate" Reusing "open" BPF sys_enter augmenter for "chdir" Reusing "open" BPF sys_enter augmenter for "mkdir" Reusing "open" BPF sys_enter augmenter for "rmdir" Reusing "open" BPF sys_enter augmenter for "creat" Reusing "open" BPF sys_enter augmenter for "link" Reusing "open" BPF sys_enter augmenter for "unlink" Reusing "open" BPF sys_enter augmenter for "symlink" Reusing "open" BPF sys_enter augmenter for "readlink" Reusing "open" BPF sys_enter augmenter for "chmod" Reusing "open" BPF sys_enter augmenter for "chown" Reusing "open" BPF sys_enter augmenter for "lchown" Reusing "open" BPF sys_enter augmenter for "mknod" Reusing "open" BPF sys_enter augmenter for "statfs" Reusing "open" BPF sys_enter augmenter for "pivot_root" Reusing "open" BPF sys_enter augmenter for "chroot" Reusing "open" BPF sys_enter augmenter for "acct" Reusing "open" BPF sys_enter augmenter for "swapon" Reusing "open" BPF sys_enter augmenter for "swapoff" Reusing "open" BPF sys_enter augmenter for "delete_module" Reusing "open" BPF sys_enter augmenter for "setxattr" Reusing "open" BPF sys_enter augmenter for "lsetxattr" Reusing "openat" BPF sys_enter augmenter for "fsetxattr" Reusing "open" BPF sys_enter augmenter for "getxattr" Reusing "open" BPF sys_enter augmenter for "lgetxattr" Reusing "openat" BPF sys_enter augmenter for "fgetxattr" Reusing "open" BPF sys_enter augmenter for "listxattr" Reusing "open" BPF sys_enter augmenter for "llistxattr" Reusing "open" BPF sys_enter augmenter for "removexattr" Reusing "open" BPF sys_enter augmenter for "lremovexattr" Reusing "fsetxattr" BPF sys_enter augmenter for "fremovexattr" Reusing "open" BPF sys_enter augmenter for "mq_open" Reusing "open" BPF sys_enter augmenter for "mq_unlink" Reusing "fsetxattr" BPF sys_enter augmenter for "add_key" Reusing "fremovexattr" BPF sys_enter augmenter for "request_key" Reusing "fremovexattr" BPF sys_enter augmenter for "inotify_add_watch" Reusing "fremovexattr" BPF sys_enter augmenter for "mkdirat" Reusing "fremovexattr" BPF sys_enter augmenter for "mknodat" Reusing "fremovexattr" BPF sys_enter augmenter for "fchownat" Reusing "fremovexattr" BPF sys_enter augmenter for "futimesat" Reusing "fremovexattr" BPF sys_enter augmenter for "newfstatat" Reusing "fremovexattr" BPF sys_enter augmenter for "unlinkat" Reusing "fremovexattr" BPF sys_enter augmenter for "linkat" Reusing "open" BPF sys_enter augmenter for "symlinkat" Reusing "fremovexattr" BPF sys_enter augmenter for "readlinkat" Reusing "fremovexattr" BPF sys_enter augmenter for "fchmodat" Reusing "fremovexattr" BPF sys_enter augmenter for "faccessat" Reusing "fremovexattr" BPF sys_enter augmenter for "utimensat" Reusing "connect" BPF sys_enter augmenter for "accept4" Reusing "fremovexattr" BPF sys_enter augmenter for "name_to_handle_at" Reusing "fremovexattr" BPF sys_enter augmenter for "renameat2" Reusing "open" BPF sys_enter augmenter for "memfd_create" Reusing "fremovexattr" BPF sys_enter augmenter for "execveat" Reusing "fremovexattr" BPF sys_enter augmenter for "statx" [root@quaco ~]# Cc: Adrian Hunter Cc: Alan Maguire Cc: Ian Rogers Cc: Jiri Olsa Cc: Namhyung Kim Link: https://lore.kernel.org/lkml/ Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 3964cf44cdbcb3e8..e541d0e2777ab935 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -3398,6 +3398,19 @@ static struct bpf_program *trace__find_usable_bpf_prog_entry(struct trace *trace if (strcmp(field->type, candidate_field->type)) goto next_candidate; + /* + * This is limited in the BPF program but sys_write + * uses "const char *" for its "buf" arg so we need to + * use some heuristic that is kinda future proof... + */ + if (strcmp(field->type, "const char *") == 0 && + !(strstr(field->name, "name") || + strstr(field->name, "path") || + strstr(field->name, "file") || + strstr(field->name, "root") || + strstr(field->name, "description"))) + goto next_candidate; + is_candidate = true; } -- 2.41.0