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 F068A111A8 for ; Thu, 24 Aug 2023 14:15:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 703F0C433C8; Thu, 24 Aug 2023 14:15:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1692886533; bh=ku46R3nMTxJvAhX2qfk6n2OZ1fmeak2j4wyA6XofgR8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cau5dqiEJlDaQzP2OjU+APCi6KS0VvaMromQwENrqRhdxCCAGdK2HZzVGeFYsXxyD CYsNwlfvrDrJgge3J/KAIm8TQxE1vzL6wMfTKJsSeZqfk5ctHRGGMU4r+0cP1z1uyO WrfL2NlrYp4H+Fb3vQ4To2Z21HjvogqPAU5AW2Zo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Petr Pavlu , "Peter Zijlstra (Intel)" , Nathan Chancellor , "Borislav Petkov (AMD)" Subject: [PATCH 6.1 13/15] x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG Date: Thu, 24 Aug 2023 16:15:09 +0200 Message-ID: <20230824141447.774063914@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230824141447.155846739@linuxfoundation.org> References: <20230824141447.155846739@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Petr Pavlu commit 79cd2a11224eab86d6673fe8a11d2046ae9d2757 upstream. The linker script arch/x86/kernel/vmlinux.lds.S matches the thunk sections ".text.__x86.*" from arch/x86/lib/retpoline.S as follows: .text { [...] TEXT_TEXT [...] __indirect_thunk_start = .; *(.text.__x86.*) __indirect_thunk_end = .; [...] } Macro TEXT_TEXT references TEXT_MAIN which normally expands to only ".text". However, with CONFIG_LTO_CLANG, TEXT_MAIN becomes ".text .text.[0-9a-zA-Z_]*" which wrongly matches also the thunk sections. The output layout is then different than expected. For instance, the currently defined range [__indirect_thunk_start, __indirect_thunk_end] becomes empty. Prevent the problem by using ".." as the first separator, for example, ".text..__x86.indirect_thunk". This pattern is utilized by other explicit section names which start with one of the standard prefixes, such as ".text" or ".data", and that need to be individually selected in the linker script. [ nathan: Fix conflicts with SRSO and fold in fix issue brought up by Andrew Cooper in post-review: https://lore.kernel.org/20230803230323.1478869-1-andrew.cooper3@citrix.com ] Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO") Signed-off-by: Petr Pavlu Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Nathan Chancellor Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230711091952.27944-2-petr.pavlu@suse.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/vmlinux.lds.S | 8 ++++---- arch/x86/lib/retpoline.S | 8 ++++---- tools/objtool/check.c | 2 +- 3 files changed, 9 insertions(+), 9 deletions(-) --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -134,7 +134,7 @@ SECTIONS KPROBES_TEXT ALIGN_ENTRY_TEXT_BEGIN #ifdef CONFIG_CPU_SRSO - *(.text.__x86.rethunk_untrain) + *(.text..__x86.rethunk_untrain) #endif ENTRY_TEXT @@ -145,7 +145,7 @@ SECTIONS * definition. */ . = srso_alias_untrain_ret | (1 << 2) | (1 << 8) | (1 << 14) | (1 << 20); - *(.text.__x86.rethunk_safe) + *(.text..__x86.rethunk_safe) #endif ALIGN_ENTRY_TEXT_END SOFTIRQENTRY_TEXT @@ -154,8 +154,8 @@ SECTIONS #ifdef CONFIG_RETPOLINE __indirect_thunk_start = .; - *(.text.__x86.indirect_thunk) - *(.text.__x86.return_thunk) + *(.text..__x86.indirect_thunk) + *(.text..__x86.return_thunk) __indirect_thunk_end = .; #endif } :text =0xcccc --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -11,7 +11,7 @@ #include #include - .section .text.__x86.indirect_thunk + .section .text..__x86.indirect_thunk .macro RETPOLINE reg ANNOTATE_INTRA_FUNCTION_CALL @@ -91,7 +91,7 @@ SYM_CODE_END(__x86_indirect_thunk_array) * As a result, srso_alias_safe_ret() becomes a safe return. */ #ifdef CONFIG_CPU_SRSO - .section .text.__x86.rethunk_untrain + .section .text..__x86.rethunk_untrain SYM_START(srso_alias_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) UNWIND_HINT_FUNC @@ -102,7 +102,7 @@ SYM_START(srso_alias_untrain_ret, SYM_L_ SYM_FUNC_END(srso_alias_untrain_ret) __EXPORT_THUNK(srso_alias_untrain_ret) - .section .text.__x86.rethunk_safe + .section .text..__x86.rethunk_safe #else /* dummy definition for alternatives */ SYM_START(srso_alias_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) @@ -120,7 +120,7 @@ SYM_START(srso_alias_safe_ret, SYM_L_GLO int3 SYM_FUNC_END(srso_alias_safe_ret) - .section .text.__x86.return_thunk + .section .text..__x86.return_thunk SYM_CODE_START(srso_alias_return_thunk) UNWIND_HINT_FUNC --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -379,7 +379,7 @@ static int decode_instructions(struct ob if (!strcmp(sec->name, ".noinstr.text") || !strcmp(sec->name, ".entry.text") || - !strncmp(sec->name, ".text.__x86.", 12)) + !strncmp(sec->name, ".text..__x86.", 13)) sec->noinstr = true; for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {