From patchwork Wed Jul 5 08:15:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Petr Pavlu X-Patchwork-Id: 13301831 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22785C001B1 for ; Wed, 5 Jul 2023 08:16:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232454AbjGEIQT (ORCPT ); Wed, 5 Jul 2023 04:16:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232448AbjGEIQS (ORCPT ); Wed, 5 Jul 2023 04:16:18 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEA3918B; Wed, 5 Jul 2023 01:16:16 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 98DCF22759; Wed, 5 Jul 2023 08:16:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1688544975; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=s/QzpkL3eR+kFPIlxO/QnNZXPq02PnM7/83/wB+Buqo=; b=FAZFennVRgNkYCRDDJU9ZhrrAp82fkJ2zEP01TDygpvCy8slWxBMR+EyBGjKYnyajVvSL3 MjGsr8ArVQPdVltVmQOmVfYkpvhBiaK9lCNrmSDdgGONonbdH6zAAp32LBYxvXGSq45lpU WH34QBGfpHsEdryD9d1HjVKTuKUH9uw= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 684FE13460; Wed, 5 Jul 2023 08:16:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 0CKkGM8mpWRkRwAAMHmgww (envelope-from ); Wed, 05 Jul 2023 08:16:15 +0000 From: Petr Pavlu To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mhiramat@kernel.org Cc: peterz@infradead.org, samitolvanen@google.com, x86@kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Pavlu Subject: [PATCH 1/2] x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG Date: Wed, 5 Jul 2023 10:15:46 +0200 Message-Id: <20230705081547.25130-2-petr.pavlu@suse.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230705081547.25130-1-petr.pavlu@suse.com> References: <20230705081547.25130-1-petr.pavlu@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org 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 range [__indirect_thunk_start, __indirect_thunk_end] is then empty. A visible result is that function insn_is_indirect_jump() misbehaves and optprobes become allowed in functions where they are not potentially safe. Fix the problem by using ".." as the first separator, for instance, ".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. Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO") Signed-off-by: Petr Pavlu Acked-by: Peter Zijlstra (Intel) --- arch/x86/kernel/vmlinux.lds.S | 2 +- arch/x86/lib/retpoline.S | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 03c885d3640f..a4cd04c458df 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -134,7 +134,7 @@ SECTIONS SOFTIRQENTRY_TEXT #ifdef CONFIG_RETPOLINE __indirect_thunk_start = .; - *(.text.__x86.*) + *(.text..__x86.*) __indirect_thunk_end = .; #endif STATIC_CALL_TEXT diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index 3fd066d42ec0..3bea96341d00 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -12,7 +12,7 @@ #include #include - .section .text.__x86.indirect_thunk + .section .text..__x86.indirect_thunk .macro POLINE reg @@ -131,7 +131,7 @@ SYM_CODE_END(__x86_indirect_jump_thunk_array) */ #ifdef CONFIG_RETHUNK - .section .text.__x86.return_thunk + .section .text..__x86.return_thunk /* * Safety details here pertain to the AMD Zen{1,2} microarchitecture: