From nobody Mon Apr 6 23:08:49 2026 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 A61C33F789E; Tue, 17 Mar 2026 22:51:38 +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=1773787898; cv=none; b=NqHgIZnuwiMBT6angEkI9eqaCx6YQR3UVf5lS03whW2q0XSaY1UWPxHXEowNhN3LdDt7W6UhfairoITjB/l+9kabI/eekPOZNrbhroX9q32UTpuog+TK7OltiYBlzQEEwCZO8rASuhipWSSx2AancyCJPc5ain5pudnY9AHSjHo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773787898; c=relaxed/simple; bh=Z4h9ZFd5elXdJi4wGJjXHxGFSPzvcEc4LERNhrT0EmE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ba02IWoHTej++wKTAI6x/ZEbfg41FDny9UY1S5pLCYczgZ47hfMPrScH9ex98/nTgg3xmPSXkYN+MjtkftZBxsfWzJf/CBaCaEG29tav05/YY5ZOG9PuNoKxz+nM1On+BmCvxVlkO+2Rqw/d4vfcMuri7U9V/+5NBxs09S6h9Eg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SEISourM; 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="SEISourM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2B9AC2BCC9; Tue, 17 Mar 2026 22:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773787898; bh=Z4h9ZFd5elXdJi4wGJjXHxGFSPzvcEc4LERNhrT0EmE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SEISourMafINQsXcWHU2ATrORkFpttHBZjwLuKpsPpemhVE9HhqmUB/CM6T7M+htA DYR0J4BPPJCqkO96EfctVeIRhNhiRLAvPU5cmdOsi90QQyMQrniTmVNwycGCcxdZtP hUAS/YwgmhrOOeAMFmuLxT76aTwikXppqOtUIK3+2H4AgFwL2Ka+5/z9AvxduJ4KSH muy19v9dvnYxKctPAlxrXxOPWTPgau7SvFtbYeNssU2rgJd8uB0xiw/MssIc9cRMp9 eV/paCwa/QWLJSEsjjT7UXNvOhbYHqXo7B093waN/tT+DwUawc6WLzRPUJASZ2Sb6Z NlLQqnKt12HXw== From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Peter Zijlstra , Joe Lawrence , Song Liu , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Mark Rutland , Nathan Chancellor , Nicolas Schier , Herbert Xu Subject: [PATCH v2 10/12] objtool: Reuse consecutive string references Date: Tue, 17 Mar 2026 15:51:10 -0700 Message-ID: <4d211040356fe169b4236b3deea1cdff80e9babc.1773787568.git.jpoimboe@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For duplicate strings, elf_add_string() just blindly adds duplicates. That can be a problem for arm64 which often uses two consecutive instructions (and corresponding relocations) to put an address into a register, like: d8: 90000001 adrp x1, 0 d8: R_AARCH= 64_ADR_PREL_PG_HI21 .rodata.meminfo_proc_show.str1.8 dc: 91000021 add x1, x1, #0x0 dc: R_AARCH64_ADD_ABS_LO12_= NC .rodata.meminfo_proc_show.str1.8 Referencing two different string addresses in the adrp+add pair can result in a corrupt string addresses. Detect such consecutive reuses and force them to use the same string. Acked-by: Song Liu Signed-off-by: Josh Poimboeuf --- tools/objtool/elf.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index b911abe3a15e..5ccae2c937dc 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -1374,6 +1374,8 @@ struct elf *elf_create_file(GElf_Ehdr *ehdr, const ch= ar *name) =20 unsigned int elf_add_string(struct elf *elf, struct section *strtab, const= char *str) { + static unsigned int last_off; + static const char *last_str; unsigned int offset; =20 if (!strtab) @@ -1382,17 +1384,22 @@ unsigned int elf_add_string(struct elf *elf, struct= section *strtab, const char ERROR("can't find .strtab section"); return -1; } - if (!strtab->sh.sh_addralign) { ERROR("'%s': invalid sh_addralign", strtab->name); return -1; } =20 + if (last_str && !strcmp(last_str, str)) + return last_off; + offset =3D ALIGN(sec_size(strtab), strtab->sh.sh_addralign); =20 if (!elf_add_data(elf, strtab, str, strlen(str) + 1)) return -1; =20 + last_str =3D str; + last_off =3D offset; + return offset; } =20 --=20 2.53.0