From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-103.mta0.migadu.com [91.218.175.103]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11700559CA3 for ; Wed, 9 Sep 2026 12:48:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.103 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788958087; cv=none; b=MjLQdF0DWSfF3JRG8il10k3cO0Al/B5t7koscHXICKFTZnVECv5x4/KZSEfAPBJSncPvgUSOiXGiKLpvB56iE/eoJd10jbqSL3EtcnsjX/vJw890E/e5ZXmm8QHSfh/z22ZAbddj2dD5NwhH4c3KePItOJV05TiyAC0W3maMOaU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788958087; c=relaxed/simple; bh=y53Xk9bhjBTIXj1qHAyuohp/PrZA0avTM6UpmR+cniQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=e94hAghLhZFd1LQ9+VWduH0PA8RBDzNkzyvgdq3Ik4llNu2ZjVNsps8if+XqbQnA0oonIVshJFerFke6tOpsD77tPTEgAEUghV+Gytf6UPzdO5Y5NTz7l6mr04DpWOXf6yCIz4lIbF6jCCGntM+1OMsvUiB0TSSNf5Bh/Rts/70= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=W0yCmiDX; arc=none smtp.client-ip=91.218.175.103 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="W0yCmiDX" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=y53Xk9bhjBTIXj1qHAyuohp/PrZA0avTM6UpmR+cniQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788958081; v=1; x=1789562881; b=W0yCmiDX9lZ45zMFQBltGBMWSA+Wryts6ERBRLO/S6rNbILU07JYXG0mSScxOEwveWmFUXWl h2FLXjkSnA5y7uOzHkU6zU4pG9zylucwtXGALfVv4BNWXlGUoykT3rkGEihrVyZHi3zpJESRE+w /ESESswo9dN7Mf3vU/iLB38A= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id cd2dbaa2e085f090; Wed, 09 Sep 2026 12:48:01 +0000 X-Mizu-Trace-ID: cd2dbaa2e085f090 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Wed, 9 Sep 2026 20:47:52 +0800 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 v9 3/4] module: introduce SH_ENTSIZE_STANDALONE for separately allocated sections To: Petr Pavlu Cc: Luis Chamberlain , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Suren Baghdasaryan , Andrew Morton , linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Sashiko , stable@vger.kernel.org References: <20260908092412.115953-1-hao.ge@linux.dev> <20260908092412.115953-4-hao.ge@linux.dev> <76b5edbb-8231-41d0-9e7b-f965af13c324@suse.com> Content-Language: en-US From: Hao Ge In-Reply-To: <76b5edbb-8231-41d0-9e7b-f965af13c324@suse.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Petr On 9/9/26 19:30, Petr Pavlu wrote: > On 9/8/26 11:24 AM, Hao Ge wrote: >> SHF_ALLOC means, per the ELF spec, that a section occupies memory >> during process execution. Some module sections occupy memory >> outside the regular module layout, for example the percpu section >> with its per-CPU allocations. The loader currently excludes such >> a section from the layout by clearing its SHF_ALLOC, which >> overloads the flag with a loader-internal meaning. >> apply_relocations() needs a special case for the section, and >> find_sec(".data..percpu") returns different results before and >> after layout_and_allocate(). >> >> Introduce SH_ENTSIZE_STANDALONE to mark sections with a separate >> allocation. The percpu section is its first user. layout_sections() >> and move_module() skip marked sections, and apply_relocations() goes >> back to testing only SHF_ALLOC. Based on a patch by Petr Pavlu [1]. >> >> .data..percpu keeps SHF_ALLOC, so it would now show up under >> /sys/module/*/sections/. The section has one instance per CPU and no >> single address to report, and the entry never existed before, so >> skip it in add_sect_attrs(). add_notes_attrs() indexes its attrs[] >> array and skips it too. No functional change otherwise. >> >> Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression") >> Reported-by: Sashiko >> Link: https://lore.kernel.org/all/499bb60c-c6e3-43a3-bd92-95a0567ece5e@suse.com/ [1] >> Suggested-by: Petr Pavlu >> Cc: stable@vger.kernel.org >> Signed-off-by: Hao Ge >> --- >> [...] >> diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c >> index 0fc11e45df9b..49190deae61e 100644 >> --- a/kernel/module/kallsyms.c >> +++ b/kernel/module/kallsyms.c >> @@ -76,7 +76,7 @@ static char elf_type(const Elf_Sym *sym, const struct load_info *info) >> } >> >> static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs, >> - unsigned int shnum, unsigned int pcpundx) >> + unsigned int shnum) >> { >> const Elf_Shdr *sec; >> enum mod_mem_type type; >> @@ -86,11 +86,6 @@ static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs, >> !src->st_name) >> return false; >> >> -#ifdef CONFIG_KALLSYMS_ALL >> - if (src->st_shndx == pcpundx) >> - return true; >> -#endif >> - >> sec = sechdrs + src->st_shndx; >> type = sec->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; >> if (!(sec->sh_flags & SHF_ALLOC) >> @@ -131,8 +126,7 @@ void layout_symtab(struct module *mod, struct load_info *info) >> /* Compute total space required for the core symbols' strtab. */ >> for (ndst = i = 0; i < nsrc; i++) { >> if (i == 0 || is_livepatch_module(mod) || >> - is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum, >> - info->index.pcpu)) { >> + is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum)) { >> strtab_size += strlen(&info->strtab[src[i].st_name]) + 1; >> ndst++; >> } >> @@ -199,8 +193,7 @@ void add_kallsyms(struct module *mod, const struct load_info *info) >> for (ndst = i = 0; i < kallsyms->num_symtab; i++) { >> kallsyms->typetab[i] = elf_type(src + i, info); >> if (i == 0 || is_livepatch_module(mod) || >> - is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum, >> - info->index.pcpu)) { >> + is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum)) { >> ssize_t ret; >> >> mod->core_kallsyms.typetab[ndst] = > FTR These changes in kernel/module/kallsyms.c have a conflict with the > series "Ignore local labels and mapping symbols during module load" [1], > which is currently queued on modules-next, but it should be > straightforward to resolve. > >> diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c >> index 01c65d608873..f64170344e69 100644 >> --- a/kernel/module/sysfs.c >> +++ b/kernel/module/sysfs.c >> @@ -62,6 +62,15 @@ static void free_sect_attrs(struct module_sect_attrs *sect_attrs) >> kfree(sect_attrs); >> } >> >> +/* >> + * .data..percpu has a separate allocation per CPU and no single >> + * address to report. >> + */ >> +static bool sect_visible(const struct load_info *info, unsigned int i) >> +{ >> + return !sect_empty(&info->sechdrs[i]) && i != info->index.pcpu; >> +} >> + >> static int add_sect_attrs(struct module *mod, const struct load_info *info) >> { >> struct module_sect_attrs *sect_attrs; >> @@ -72,7 +81,7 @@ static int add_sect_attrs(struct module *mod, const struct load_info *info) >> >> /* Count loaded sections and allocate structures */ >> for (i = 0; i < info->hdr->e_shnum; i++) >> - if (!sect_empty(&info->sechdrs[i])) >> + if (sect_visible(info, i)) >> nloaded++; >> sect_attrs = kzalloc_flex(*sect_attrs, attrs, nloaded); >> if (!sect_attrs) >> @@ -92,7 +101,7 @@ static int add_sect_attrs(struct module *mod, const struct load_info *info) >> for (i = 0; i < info->hdr->e_shnum; i++) { >> Elf_Shdr *sec = &info->sechdrs[i]; >> >> - if (sect_empty(sec)) >> + if (!sect_visible(info, i)) >> continue; >> sysfs_bin_attr_init(sattr); >> sattr->attr.name = >> @@ -181,7 +190,7 @@ static int add_notes_attrs(struct module *mod, const struct load_info *info) >> >> nattr = ¬es_attrs->attrs[0]; >> for (loaded = i = 0; i < info->hdr->e_shnum; ++i) { >> - if (sect_empty(&info->sechdrs[i])) >> + if (!sect_visible(info, i)) >> continue; >> if (info->sechdrs[i].sh_type == SHT_NOTE) { >> sysfs_bin_attr_init(nattr); > add_notes_attrs() has two sect_empty() calls. Both should be changed to > sect_visible(). I kept this part unmodified to preserve the loop's original intent. This loop counts SHT_NOTE sections. SHT_NOTE refers to ELF note sections, which hold non-executable metadata such as build ID and ABI info. I wonder if we could keep the current implementation. As noted in the comment above, the top part counts SHT_NOTE sections and allocates structures, while the lower logic handles control of node attributes. WDYT? Thanks Best Regards Hao > > With this fixed, the patch looks ok to me. Feel free to add: > > Reviewed-by: Petr Pavlu > > [1] https://lore.kernel.org/linux-modules/20260820125007.22943-1-yangtiezhu@loongson.cn/ >