From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (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 7E4CE3E7BC6; Wed, 8 Jul 2026 08:07:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.132 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783498050; cv=none; b=ZzC4pyBUGS8VO1bJzCHLAvZ1Vh4oS6F925tzahlmTj4gaWoLLq4KosCd6UaJH79HHZurHriTrX9ZEy7r7XH1eXQvKl1QcDcwBvH2WRrw82cwN7zGFqBnnMHCGygGOxdGa8IpWAjjveZ4orj3C8fNcTg0nC0lOhATKjcWnfIWlyU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783498050; c=relaxed/simple; bh=t5aDYhWDsenCSPBFg8sFWKNzaG45c943wAdMkXPrlFM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=THeHqoLaQ/wF/DutuY30wicWI5GBtLSae9pPl1ybFqUgOIt7dL+H6Cusy9Um30nzlJVsWHcmDlisNOrOLT6R75u2+z3D25HBxMyFQyT6kV4sOWScfoEBkxeCrbJC1wRrTrYJPVFX3I2/U0cL2pCaukEdVcgFbY4VlQ4Bgop1rgA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=TSI9Owt9; arc=none smtp.client-ip=115.124.30.132 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="TSI9Owt9" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1783498041; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=7aX7B+3xkHbNhiVcp4PAYQLzOnDUqkKktfRxNWYRSCI=; b=TSI9Owt9xFK3U5bQlUri1HJ35iDcK98p5Wj7bR1IfzPOqUOG7bGCt6Fsp9bgDmvdgAScS2KdXjeb9kjdFyM2WQj76YOjBenDgO7hHntCduFoTbHwu1GGE4ectC0NmrLSM5VqfFxrmHuWzFEDlvkLv7h/9YdIYUujG3Sds2psbeQ= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037009110;MF=xueshuai@linux.alibaba.com;NM=1;PH=DS;RN=34;SR=0;TI=SMTPD_---0X6h5OsU_1783498037; Received: from 30.246.161.237(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0X6h5OsU_1783498037 cluster:ay36) by smtp.aliyun-inc.com; Wed, 08 Jul 2026 16:07:19 +0800 Message-ID: <9986b3bf-e80e-4ffc-afd6-6b82baa1e9d0@linux.alibaba.com> Date: Wed, 8 Jul 2026 16:07:17 +0800 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 RESEND 2/7] riscv: stacktrace: disable KASAN and KCOV instrumentation for stacktrace.o To: Wang Han , Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: Alexandre Ghiti , linux-riscv@lists.infradead.org, Oleg Nesterov , Steven Rostedt , Masami Hiramatsu , Mark Rutland , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , oliver.yang@linux.alibaba.com, zhuo.song@linux.alibaba.com, jkchen@linux.alibaba.com, Marcos Paulo de Souza , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, live-patching@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260629072713.3273743-1-wanghan@linux.alibaba.com> <20260629072713.3273743-3-wanghan@linux.alibaba.com> From: Shuai Xue In-Reply-To: <20260629072713.3273743-3-wanghan@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/29/26 3:27 PM, Wang Han wrote: > KASAN records stack traces for every alloc/free, which means it walks > the unwinder very frequently. Instrumenting the stack trace collection > code itself adds substantial overhead and makes the traces themselves > noisier. > > KCOV instruments every basic-block edge. The unwinder is a hot path, > especially with KASAN enabled, so KCOV instrumentation has the same kind > of cost and noise problem here. > > Mark stacktrace.o as not KASAN- or KCOV-instrumented, matching the x86 > treatment of its stack unwinding code. RISC-V keeps the relevant unwinder > code in stacktrace.o, so a single translation-unit annotation covers the > equivalent scope. This is a prerequisite preference for the upcoming > reliable unwinder, but the change is valid on its own. > > Signed-off-by: Wang Han > --- > arch/riscv/kernel/Makefile | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > index cabb99cadfb6..c565a72a36f3 100644 > --- a/arch/riscv/kernel/Makefile > +++ b/arch/riscv/kernel/Makefile > @@ -44,6 +44,12 @@ CFLAGS_REMOVE_return_address.o = $(CC_FLAGS_FTRACE) > CFLAGS_REMOVE_sbi_ecall.o = $(CC_FLAGS_FTRACE) > endif > > +# When KASAN is enabled, a stack trace is recorded for every alloc/free, which > +# can significantly impact performance. Avoid instrumenting the stack trace > +# collection code to minimize this impact. > +KASAN_SANITIZE_stacktrace.o := n > +KCOV_INSTRUMENT_stacktrace.o := n > + > always-$(KBUILD_BUILTIN) += vmlinux.lds > > obj-y += head.o Reviewed-by: Shuai Xue Thanks. Shuai