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 C765E8BFF; Mon, 9 Jun 2025 13:48:04 +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=1749476884; cv=none; b=MqJYzInwjfvuBIAh/QucKLX5H0rxExNRMF2/sFBRJcdAyhveDPqbfk9MwYQ946UWewSqZlubFpNVMFK/D4GOHWGMaa45NSJ1DmKNvxS8qvSlzxa4fInmiN/cqLqYwfk7pUW/ZKiVEyNvXR5p/Ic/JVsnMR+JZ1x59vbSqNYVjjI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749476884; c=relaxed/simple; bh=qrZpZsMrsU1gfoQb0W7EnINpdzrBuhVDdB9nntc+yHM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=LNergJ8ad4xKkj8KeG+WuTh+neD7SfC0ivISb7y+kLTUp8RYVAf6dJvOy96nT9/v4mB6OiTvBsQbl5MM3RfVRBNqYabSD03b0Kk5UYFg3jtt1LWkg3GZNpLbrZbqWUneiTVN4H/12aC0Lk5txqB01P7faYJQVNifeSAxlmEl1js= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PQJZGA8E; 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="PQJZGA8E" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5D95C4CEF0; Mon, 9 Jun 2025 13:48:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749476884; bh=qrZpZsMrsU1gfoQb0W7EnINpdzrBuhVDdB9nntc+yHM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PQJZGA8EIeOaVWgoRBjpGdLDPVrS+4D4DZYH+uZE4mvO6Z+5+TvXp6r6X+p0d9TCH TudQ4I2HiGHqcTEYEdnCHxU3ospRyEJrKOW10KdRmSyFBKI6SElqalgA7QSKmBiFWp XaQLmtm1Fah9cH/WiXXlC/QIAl2embQvVgJrKaM/Af8ryKOLPmXti88AL+EcrSksjn VFFI60M2hRMQ+IadJaRW0DnP4eeO4EC/y3RYY948eAPulqHS84SKZDjThpk4A8z0GV zvPjDaOnsk6TQhSUCXy/PkYPYHwzia600txu8suMCwNa5jfe0jkEt2bVBCLka+E5Zq Ruf0r/96mnhIQ== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Sami Tolvanen , Masahiro Yamada , linux-kbuild@vger.kernel.org, kernel test robot , Johannes Berg , Sasha Levin Subject: [PATCH AUTOSEL 5.15 04/12] um: Add cmpxchg8b_emu and checksum functions to asm-prototypes.h Date: Mon, 9 Jun 2025 09:47:47 -0400 Message-Id: <20250609134755.1345286-4-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250609134755.1345286-1-sashal@kernel.org> References: <20250609134755.1345286-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.185 Content-Transfer-Encoding: 8bit From: Sami Tolvanen [ Upstream commit 674d03f6bd6b0f8327f1a4920ff5893557facfbd ] With CONFIG_GENDWARFKSYMS, um builds fail due to missing prototypes in asm/asm-prototypes.h. Add declarations for cmpxchg8b_emu and the exported checksum functions, including csum_partial_copy_generic as it's also exported. Cc: Masahiro Yamada Cc: linux-kbuild@vger.kernel.org Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202503251216.lE4t9Ikj-lkp@intel.com/ Signed-off-by: Sami Tolvanen Link: https://patch.msgid.link/20250326190500.847236-2-samitolvanen@google.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- **YES** This commit should be backported to stable kernel trees based on the following analysis: ## Analysis ### Purpose and Context This commit fixes a build failure in the User Mode Linux (UM) architecture when `CONFIG_GENDWARFKSYMS` is enabled. The `CONFIG_GENDWARFKSYMS` feature is a new kernel build system enhancement for generating DWARF-based symbol versioning, which requires proper prototypes in `asm-prototypes.h` files to generate correct CRCs for exported symbols. ### Code Changes Analysis **File 1: `arch/um/include/asm/asm-prototypes.h`** - **Before**: Only included the generic asm-prototypes.h - **After**: Added includes for `` and conditional declaration of `cmpxchg8b_emu()` for `CONFIG_UML_X86` **File 2: `arch/x86/um/asm/checksum.h`** - **Before**: Only declared `csum_partial()` function - **After**: Added declaration for `csum_partial_copy_generic()` with a comment explaining it's for export type visibility ### Why This Should Be Backported 1. **Fixes Important Build Failures**: This directly addresses build failures when `CONFIG_GENDWARFKSYMS` is enabled for UM architecture, as confirmed by the kernel test robot report. 2. **Minimal Risk Changes**: - Only adds function declarations, no implementation changes - Changes are confined to UM architecture headers - No behavioral changes to existing code paths 3. **Follows Established Patterns**: Similar commits in the reference history (Similar Commit #1 and #5) that add missing prototypes to `asm-prototypes.h` files were marked as "YES" for backporting. This follows the exact same pattern. 4. **Critical Infrastructure Fix**: The `asm-prototypes.h` infrastructure is essential for proper symbol versioning. Missing prototypes can cause genksyms to segfault during build, making this a critical build system fix. 5. **Architecture-Specific Scope**: Changes are limited to UM architecture, reducing risk of regressions in other subsystems. 6. **Self-Contained**: The fix includes both the missing `cmpxchg8b_emu` prototype (conditional on `CONFIG_UML_X86`) and the checksum function declarations, making it complete. ### Comparison to Reference Commits - **Similar to Commit #1**: Adds missing prototypes for genksyms CRC generation (Status: YES) - **Similar to Commit #5**: Fixes missing prototypes causing build issues with symbol versioning (Status: YES) - **Unlike Commits #2, #3, #4**: This is not just a comment update or cleanup, but fixes actual build failures The fix addresses a concrete build failure affecting users who enable `CONFIG_GENDWARFKSYMS` with UM, making it an important bugfix that meets stable tree criteria for backporting. arch/um/include/asm/asm-prototypes.h | 5 +++++ arch/x86/um/asm/checksum.h | 3 +++ 2 files changed, 8 insertions(+) diff --git a/arch/um/include/asm/asm-prototypes.h b/arch/um/include/asm/asm-prototypes.h index 5898a26daa0dd..408b31d591279 100644 --- a/arch/um/include/asm/asm-prototypes.h +++ b/arch/um/include/asm/asm-prototypes.h @@ -1 +1,6 @@ #include +#include + +#ifdef CONFIG_UML_X86 +extern void cmpxchg8b_emu(void); +#endif diff --git a/arch/x86/um/asm/checksum.h b/arch/x86/um/asm/checksum.h index b07824500363f..ddc144657efad 100644 --- a/arch/x86/um/asm/checksum.h +++ b/arch/x86/um/asm/checksum.h @@ -20,6 +20,9 @@ */ extern __wsum csum_partial(const void *buff, int len, __wsum sum); +/* Do not call this directly. Declared for export type visibility. */ +extern __visible __wsum csum_partial_copy_generic(const void *src, void *dst, int len); + /** * csum_fold - Fold and invert a 32bit checksum. * sum: 32bit unfolded sum -- 2.39.5