From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) (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 6BAEB3B995E; Tue, 2 Jun 2026 11:22:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780399379; cv=none; b=avstqWZ52BUNinhXbzR8GU1zB+54mn+p93wcSKdAXtGC3o1Zn3g6w6UheAjwWSY27bBaJiiS0wmPQACueW+ovRZG3cFr4yKwq2Rk8IZT0rpckokI+uINw90Z6wE9pXna1VG9la3BXO7s3kxhvyqfuC2KorLG1ykmqbuE0bF19q0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780399379; c=relaxed/simple; bh=2hnGczsE61WJKJTsFKGPfGzYvBHWq7w+13htcig3JQc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=E8sCbsMjdVotw10Gos0MwUTYpBj9wsdN0IX6mYZj4SBLY/lpE22CzSk7jOosnuO0U5XXyrhEsP7/jeK5BA2LM5CDFlSwZRszyPy2qpXCaCFHu553NsbhlFnC1oBDjDl4HBQU6q9APv7K5rzR7jXpHxWEgFWw/Z5i+9fZozGQs8I= 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=ld2B9ySg; arc=none smtp.client-ip=115.124.30.124 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="ld2B9ySg" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1780399373; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Zbw5BKJXHyNT/TPLzF2MYusKHtOC6lHLUdejhNl1Q64=; b=ld2B9ySg6F8F9XA/6m5nnP0Y1YKK264jBfRluFKD3qskhQC4jGRCO+yFUZRhxfr38WTt62sSJWVZ9e+BOEFlWm2P0RYSDgZt4UMegURoMyDwjZzkAA9WGOdQ05PQyzQB5RVrPfgE3Nwfbhl1yitjKCxZFRA3TRLESrAI3JBl288= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R831e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037026112;MF=xueshuai@linux.alibaba.com;NM=1;PH=DS;RN=34;SR=0;TI=SMTPD_---0X44JnKC_1780399369; Received: from 30.100.154.88(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0X44JnKC_1780399369 cluster:ay36) by smtp.aliyun-inc.com; Tue, 02 Jun 2026 19:22:51 +0800 Message-ID: Date: Tue, 2 Jun 2026 19:22:49 +0800 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/8] riscv: stacktrace: disable KASAN instrumentation for stacktrace.o To: Wang Han , Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: Steven Rostedt , Alexandre Ghiti , Masami Hiramatsu , Mark Rutland , Catalin Marinas , Chen Pei , Andy Chiu , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Deepak Gupta , Puranjay Mohan , Conor Dooley , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , oliver.yang@linux.alibaba.com, zhuo.song@linux.alibaba.com, jkchen@linux.alibaba.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, live-patching@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-perf-users@vger.kernel.org References: <20260527123530.2593918-1-wanghan@linux.alibaba.com> <20260528082310.1994388-4-wanghan@linux.alibaba.com> From: Shuai Xue In-Reply-To: <20260528082310.1994388-4-wanghan@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/28/26 4:23 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. > > Mark stacktrace.o as not KASAN-instrumented, matching the arm, arm64 > and x86 treatment of their stack unwinding code. 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 | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > index cabb99cadfb6..1cb6c9ab2981 100644 > --- a/arch/riscv/kernel/Makefile > +++ b/arch/riscv/kernel/Makefile > @@ -44,6 +44,11 @@ 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 > + I checked the three referenced arches: - arm (arch/arm/kernel/Makefile): KASAN only - arm64 (arch/arm64/kernel/Makefile): KASAN only - x86 (arch/x86/kernel/Makefile): KASAN *and* KCOV (KCOV_INSTRUMENT_stacktrace.o := n, plus dumpstack and the unwind_*.o TUs) So as written, this patch matches arm/arm64 but NOT x86. KCOV instruments every basic-block edge; the unwinder is a hot path (doubly so under KASAN, where it runs on every alloc/free), so the same rationale that justifies disabling KASAN applies to KCOV. I'd suggest making the claim true by adding: KCOV_INSTRUMENT_stacktrace.o := n (RISC-V keeps its entire unwinder in stacktrace.o, so unlike x86 there's no dumpstack/unwind_*.o to also annotate — the single TU covers the equivalent scope.) Alternatively, if you'd rather keep it minimal, just drop "and x86" from the changelog so the claim matches the code. Thanks. Shuai 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 83BC7CD6E4A for ; Tue, 2 Jun 2026 11:23:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=/YJRZfbaDN0VDhr6uTB+pQxqFvafuy7j2sMtIDLe4wc=; b=V4rj10vXVxX/iK mxcsW+eCplxUZnHtnL8MdAKNOWgK4bLkgDaNnD7vvsrFggs2jxttP7PqzamEewot66FVTbKt7qrJd H7+MhB5IvBHvlXlIXfJfc+jtMLmVa0LS+Un9H1rFQ3alNRSTphAlXb52HvskUqtIRwwXfQWSifAqy Ydy14RLQFmKGGLhUutv+r9gHKuTkIAow8VVWvJ7B3Wy2SrXGnj2xGYfsUKqE3GxHO93h4DgtIqvzk f3KeD5LNeFFBmtiFKVDHLK6IYtE4Cyz2I0QTbCO34++P3AvySgFdudi7ljvkabGfwniHgY1i55Mam 88Obb3zOpCGy4Lz2+PYA==; 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Received: from 30.100.154.88(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0X44JnKC_1780399369 cluster:ay36) by smtp.aliyun-inc.com; Tue, 02 Jun 2026 19:22:51 +0800 Message-ID: Date: Tue, 2 Jun 2026 19:22:49 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/8] riscv: stacktrace: disable KASAN instrumentation for stacktrace.o To: Wang Han , Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: Steven Rostedt , Alexandre Ghiti , Masami Hiramatsu , Mark Rutland , Catalin Marinas , Chen Pei , Andy Chiu , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Deepak Gupta , Puranjay Mohan , Conor Dooley , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , oliver.yang@linux.alibaba.com, zhuo.song@linux.alibaba.com, jkchen@linux.alibaba.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, live-patching@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-perf-users@vger.kernel.org References: <20260527123530.2593918-1-wanghan@linux.alibaba.com> <20260528082310.1994388-4-wanghan@linux.alibaba.com> From: Shuai Xue In-Reply-To: <20260528082310.1994388-4-wanghan@linux.alibaba.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260602_042256_038627_4B88243E X-CRM114-Status: GOOD ( 16.03 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; 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