From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F08CE7640E; Sat, 29 Nov 2025 19:07:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764443243; cv=none; b=gh3eBnrAN7HL5AO262qI1tNLcm9PdeihW0gZ+aSDafNNABYpnurr32+gC0GNWgiyHuFpAyznog2w271LxophTpDW70adO9CnWyEHdRd63Ii6AHNmrXQ/LGPMKINDSZNgyUlskIlsvv/xMBj+u3zOmPFjwsZpulXYDxsGU28l4rc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764443243; c=relaxed/simple; bh=Zkw51WqaNjqA1kvB4VKBpElPxu2esZazCU8ql+Q+Tuw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L7y4ZDORBtvNYuvvFWhm5rREI6QguUNNP52R0Dhmbe9pr2+KMhwiiJdd72V/KGdqnTlahy7m714r+v2hyIeZbgQnb9Zt0OvuY4hTVzRubHchSv/wfxS4FDrTL7lk2efpzPbRG9LBMynFjPn9oKK9X7GrqL25fOOB7vccMsG+rmI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=g4xQA9NS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="g4xQA9NS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E093C4CEF7; Sat, 29 Nov 2025 19:07:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764443242; bh=Zkw51WqaNjqA1kvB4VKBpElPxu2esZazCU8ql+Q+Tuw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=g4xQA9NSHQnu46gZ0Dk0L4/B9XOQq/k9lt0PXl2utoC6BGQX0rT+nCxJqVBp0MfDw U0We3HFclDclUdJd7rBhJkaBCaKROmb1SdMdm5MxeJPc2+/PxdxjzLk7+eXn76E7jt IXqb4WQivPyJETVk3xUJxrA0Hg9ha6ZleAEfiKO7R8rtAtAEiQAxKpV0NxnV0LJO3y XEuoOzmXqr7G178UTNtiPPDqLxXGklQ5MRml3LGYyDXvrGCNvfdSbggXkrO1UY4P0r qvdmwovKOojZsRQb51XLo8UkMzDb9TnAmZBa9MuYruOdo2spTjBmlwXgF0+0IApnYb YurEOCQLsG5Xw== Date: Sat, 29 Nov 2025 11:07:20 -0800 From: Namhyung Kim To: Steven Rostedt Cc: Arnaldo Carvalho de Melo , Ian Rogers , James Clark , Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Thomas Richter , Howard Chu Subject: Re: [PATCH] perf trace: Skip internal syscall arguments Message-ID: References: <20251127044418.677379-1-namhyung@kernel.org> <20251127203052.12a6a163@robin> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251127203052.12a6a163@robin> On Thu, Nov 27, 2025 at 08:30:52PM -0500, Steven Rostedt wrote: > On Wed, 26 Nov 2025 20:44:18 -0800 > Namhyung Kim wrote: > > > Recent changes in the linux-next kernel will add new field for syscalls > > to have contents in the userspace like below. > > > > # cat /sys/kernel/tracing/events/syscalls/sys_enter_write/format > > name: sys_enter_write > > ID: 758 > > 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; > > field:__data_loc char[] __buf_val; offset:40; size:4; signed:0; > > > > print fmt: "fd: 0x%08lx, buf: 0x%08lx (%s), count: 0x%08lx", ((unsigned long)(REC->fd)), > > ((unsigned long)(REC->buf)), __print_dynamic_array(__buf_val, 1), > > ((unsigned long)(REC->count)) > > > > We have a different way to handle those arguments and this change > > confuses perf trace then make some tests failing. Fix it by skipping > > the new fields that have "__data_loc char[]" type. > > > > Maybe we can switch to this instead of the BPF augmentation later. > > > > Even with this patch applied, I still have a segfault with this command: > > # ./perf trace -e syscalls:sys_enter_write What about this? # ./perf trace -e write Thanks, Namhyung > 0.000 sshd-session/5421 syscalls:sys_enter_write(perf: Segmentation fault > #0 0x560ea815187a in dump_stack debug.c:366 > #1 0x560ea81518f0 in sighandler_dump_stack debug.c:378 > #2 0x7fb5e14d1df0 in __restore_rt libc_sigaction.c:0 > #3 0x560ea7fc0cec in syscall_arg__scnprintf_buf builtin-trace.c:1857 > #4 0x560ea7fc2692 in syscall_arg_fmt__scnprintf_val builtin-trace.c:2398 > #5 0x560ea7fc2aad in syscall__scnprintf_args builtin-trace.c:2476 > #6 0x560ea7fc3ea2 in trace__fprintf_sys_enter builtin-trace.c:2885 > #7 0x560ea7fc57a5 in trace__event_handler builtin-trace.c:3312 > #8 0x560ea7fc68dd in trace__handle_event builtin-trace.c:3649 > #9 0x560ea7fc7f7a in __trace__deliver_event builtin-trace.c:4183 > #10 0x560ea7fc80cc in trace__deliver_event builtin-trace.c:4209 > #11 0x560ea7fc92b7 in trace__run builtin-trace.c:4577 > #12 0x560ea7fcd648 in cmd_trace builtin-trace.c:5773 > #13 0x560ea7fd35e3 in run_builtin perf.c:349 > #14 0x560ea7fd387b in handle_internal_command perf.c:401 > #15 0x560ea7fd39d4 in run_argv perf.c:448 > #16 0x560ea7fd3d1d in main perf.c:555 > #17 0x7fb5e14bbca8 in __libc_start_call_main libc_start_call_main.h:74 > #18 0x7fb5e14bbd65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > #19 0x560ea7f25f41 in _start perf[53f41] > Segmentation fault > > This doesn't crash in a kernel without the __data_loc. > > -- Steve