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 73752285050 for ; Wed, 6 May 2026 06:37:23 +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=1778049443; cv=none; b=U3JbiL7ifwFIARe79aNNUnbxghJnwj0o42rRrEddn+0O+jIPp2cAkoJls/JPok5shbMOJB775k/S9ZY6XmvHxIxdIS30w5CSUge1p8F4EDihAQGxKgVIP7A/qGK+/7Pe8+U7Z/7INysSD42cD3A2Xt54kZc1ayIgvpQnNx+0sQA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778049443; c=relaxed/simple; bh=4NVCgsre8Hue6TkSMQx2WGSTptIfhreDDsi2DSmsfK0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NUgilRMzJEZ1SXNesDXYkZUmOvyJNgVBUDn+2y49EIsp3bgpbkqNwOMIpuOGbiAL73oJkH9XPwckJAq/ve2mdKqKanlzDZiZ0XlVpLR8h7pmf9GPnTmscpXhmX4kSE34KPPyk3iigxA72y2tdupeIaLqndMWH7EzbpT5P77QV5I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YJWTpQr3; 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="YJWTpQr3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D5BDC2BCC4; Wed, 6 May 2026 06:37:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778049443; bh=4NVCgsre8Hue6TkSMQx2WGSTptIfhreDDsi2DSmsfK0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=YJWTpQr3XRNPLLO7qb7d3dSz+seP5/upwyJK7Lo4XioLYb8N6ja3y6HqYUAsVS1/j AcNEMvYJCDD/Y5PFwSITWMvyiodqXp7MqBF4tQ7Mwytwu8s2DEF7gvp3o2npd0sqpm lMD9ESkVjQKRHTc7D6EXMJr9ZbqHnA3R3heybjYaW1OSlJJ4wJGDk12G8McgwFEvU2 VSQm6KHZl8Wn/lCyVjGfmczXyiAG+R+wiX3RfZtaOBv4Q/hi2LTrchWuDg/n4G5PkJ KKCeLqn9h95x/LxYD1z1mbvZSmuUM2uikAZhJ+qMElZbrvV2g+CqfmyhiKdt4pf00I YEAnLdt2xDamw== Message-ID: <8bb836b5-daeb-491c-8588-5cde81580577@kernel.org> Date: Wed, 6 May 2026 08:37:19 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] powerpc/text-patching: simplify the implementation of ppc_kallsyms_lookup_name() To: Xie Yuanbin , maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, andriy.shevchenko@intel.com, kees@kernel.org Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, lilinjie8@huawei.com, liaohua4@huawei.com References: <20260506021143.13797-1-xieyuanbin1@huawei.com> Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: <20260506021143.13797-1-xieyuanbin1@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 06/05/2026 à 04:11, Xie Yuanbin a écrit : > ppc_kallsyms_lookup_name() is called only twice in the kernel code, and > the parameters are all constant strings. strnlen(name, KSYM_NAME_LEN) is > called inside ppc_kallsyms_lookup_name(), when the compiler detects that > KSYM_NAME_LEN is larger then the constant strings, > the following error will be triggered: > ```log > CC arch/powerpc/kernel/optprobes.o > In file included from ./arch/powerpc/include/asm/kprobes.h:24, > from ./include/linux/kprobes.h:31, > from arch/powerpc/kernel/optprobes.c:8: > In function 'ppc_kallsyms_lookup_name', > inlined from 'arch_prepare_optimized_kprobe' at arch/powerpc/kernel/optprobes.c:209:21: > ./arch/powerpc/include/asm/text-patching.h:232:13: error: 'strnlen' specified bound 512 exceeds source size 19 [-Werror=stringop-overread] > 232 | if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > In function 'ppc_kallsyms_lookup_name', > inlined from 'arch_prepare_optimized_kprobe' at arch/powerpc/kernel/optprobes.c:210:22: > ./arch/powerpc/include/asm/text-patching.h:232:13: error: 'strnlen' specified bound 512 exceeds source size 13 [-Werror=stringop-overread] > 232 | if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors > ``` > > The error can be reproduced in the following ways: > Use lastest linux-next source, change ppc_kallsyms_lookup_name() to > __always_inline, use default ppc64_defconfig, set CONFIG_EXPERT=y, > CONFIG_PPC64_BIG_ENDIAN_ELF_ABI_V2=n, CONFIG_CC_OPTIMIZE_FOR_SIZE=y, > and use gcc-14 or a later version for compilation. > > Since ppc_kallsyms_lookup_name() is called only twice in the kernel, > and the parameters are all constant strins, simplify the implementation > of ppc_kallsyms_lookup_name() and avoid calling strnlen(). > > Cc: Andy Shevchenko > Cc: Kees Cook > Suggested-by: Christophe Leroy (CS GROUP) > Signed-off-by: Xie Yuanbin Reviewed-by: Christophe Leroy (CS GROUP) > --- > v1->v2: https://lore.kernel.org/20260205100517.292858-2-xieyuanbin1@huawei.com > - Not use strlen() > > arch/powerpc/include/asm/text-patching.h | 50 ++++++++---------------- > 1 file changed, 17 insertions(+), 33 deletions(-) > > diff --git a/arch/powerpc/include/asm/text-patching.h b/arch/powerpc/include/asm/text-patching.h > index e7f14720f630..2d3f698cb4f1 100644 > --- a/arch/powerpc/include/asm/text-patching.h > +++ b/arch/powerpc/include/asm/text-patching.h > @@ -221,39 +221,23 @@ static inline unsigned long ppc_global_function_entry(void *func) > * - For ABIv1, we lookup the dot variant. > * - For ABIv2, we return the local entry point. > */ > -static inline unsigned long ppc_kallsyms_lookup_name(const char *name) > -{ > - unsigned long addr; > -#ifdef CONFIG_PPC64_ELF_ABI_V1 > - /* check for dot variant */ > - char dot_name[1 + KSYM_NAME_LEN]; > - bool dot_appended = false; > - > - if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) > - return 0; > - > - if (name[0] != '.') { > - dot_name[0] = '.'; > - dot_name[1] = '\0'; > - strlcat(dot_name, name, sizeof(dot_name)); > - dot_appended = true; > - } else { > - dot_name[0] = '\0'; > - strlcat(dot_name, name, sizeof(dot_name)); > - } > - addr = kallsyms_lookup_name(dot_name); > - if (!addr && dot_appended) > - /* Let's try the original non-dot symbol lookup */ > - addr = kallsyms_lookup_name(name); > -#elif defined(CONFIG_PPC64_ELF_ABI_V2) > - addr = kallsyms_lookup_name(name); > - if (addr) > - addr = ppc_function_entry((void *)addr); > -#else > - addr = kallsyms_lookup_name(name); > -#endif > - return addr; > -} > +static inline unsigned long __ppc_kallsyms_lookup_name(const char *name) > +{ > + unsigned long addr = kallsyms_lookup_name(name); > + > + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1) && !addr) > + addr = kallsyms_lookup_name(name + 1); > + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && addr) > + addr = ppc_function_entry((void *)addr); > + > + return addr; > +} > + > +#ifdef CONFIG_PPC64_ELF_ABI_V1 > +#define ppc_kallsyms_lookup_name(x) __ppc_kallsyms_lookup_name("." x) > +#else > +#define ppc_kallsyms_lookup_name(x) __ppc_kallsyms_lookup_name(x) > +#endif > > /* > * Some instruction encodings commonly used in dynamic ftracing