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Sun, 1 Mar 2026 19:34:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772393656; bh=BS3ZMwHlDBcAakH4xSCy5YZLU7NRjvFZNyLUzpzSoag=; h=From:To:Cc:Subject:Date:From; b=fBMoKZh/LWCvwocBJu3/DdC0EKLnEGnsvFsFINLPykRPzdRWemfcP23uVosUvNyQU LRS5bvFJZDxSZkMlwzOw4Q9gcfCc9YeJPDZ595R+nFJuTlGbuECzRBOyUNBixZFt5D iE6iCR4qfZsuoqEikqKYjCmQqHupeKgd5ohtJHLAKZG9ct5D+lRrUezJ2xNtVUijBa Af6pXyHwm+tJZeEEamUZy10vahwIWTBFKZnBtk749nsFwX6r3fnDReMFMlj+wF5hhC s98itWgns3vCxpdLt7eM0O1669ALiZebwBSZ8BHviYayyJ1j0E9NlR26Z/ra4XBWdC Zj+TlcM/lie1Q== From: "Christophe Leroy (CS GROUP)" To: Thomas Gleixner , LKML Cc: "Christophe Leroy (CS GROUP)" , Christophe Leroy , Mathieu Desnoyers , Andrew Cooper , Linus Torvalds , David Laight , kernel test robot , Russell King , linux-arm-kernel@lists.infradead.org, x86@kernel.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , linuxppc-dev@lists.ozlabs.org, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Heiko Carstens , Christian Borntraeger , Sven Schnelle , linux-s390@vger.kernel.org, Julia Lawall , Nicolas Palix , Peter Zijlstra , Darren Hart , Davidlohr Bueso , Andre Almeida , Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org Subject: [PATCH] uaccess: Fix build of scoped user access with const pointer Date: Sun, 1 Mar 2026 20:33:58 +0100 Message-ID: <4e994e13b48420ef36be686458ce3512657ddb41.1772393211.git.chleroy@kernel.org> X-Mailer: git-send-email 2.49.0 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2510; i=chleroy@kernel.org; h=from:subject:message-id; bh=BS3ZMwHlDBcAakH4xSCy5YZLU7NRjvFZNyLUzpzSoag=; b=owGbwMvMwCV2d0KB2p7V54MZT6slMWQumbKswe2Zuf6EuTudmqtKPfYcXrNP0W3Fv5jev4WbX s0s28pV0lHKwiDGxSArpshy/D/3rhldX1Lzp+7Sh5nDygQyhIGLUwAmkpLB8D+a+w/zg3+ige3h eQsXCTO+PXiEYyrjCsvO1ltzHW5ZPPvO8IspVKT412bj9XLyP/d83ZRVd+LX0vcHZX+6RcXGh8T 9EmYFAA== X-Developer-Key: i=chleroy@kernel.org; a=openpgp; fpr=10FFE6F8B390DE17ACC2632368A92FEB01B8DD78 Content-Transfer-Encoding: 8bit After converting powerpc checksum wrappers to scoped user access, following build failure happens: CC arch/powerpc/lib/checksum_wrappers.o In file included from arch/powerpc/lib/checksum_wrappers.c:12: arch/powerpc/lib/checksum_wrappers.c: In function 'csum_and_copy_from_user': ./include/linux/uaccess.h:691:1: error: initialization discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers] 691 | ({ \ | ^ ./include/linux/uaccess.h:755:37: note: in expansion of macro '__scoped_user_access_begin' 755 | for (void __user *_tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/uaccess.h:770:9: note: in expansion of macro '__scoped_user_access' 770 | __scoped_user_access(read, usrc, size, elbl) | ^~~~~~~~~~~~~~~~~~~~ arch/powerpc/lib/checksum_wrappers.c:17:9: note: in expansion of macro 'scoped_user_read_access_size' 17 | scoped_user_read_access_size(src, len, efault) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ Cast __scoped_user_access_begin() to (void __user *) to fix it. Fixes: e497310b4ffb ("uaccess: Provide scoped user access regions") Signed-off-by: Christophe Leroy (CS GROUP) --- Thomas, I encountered this problem while preparing some patches to start using scope user access widely on powerpc in order to benefit more from masked user access. Can you make this patch go into 7.0 as a fix in order avoid dependency on this change when we start using scoped user access ? include/linux/uaccess.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 1f3804245c06..5d9f6d45d301 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -752,7 +752,8 @@ USER_ACCESS_GUARD(rw) */ #define __scoped_user_access(mode, uptr, size, elbl) \ for (bool done = false; !done; done = true) \ - for (void __user *_tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl); \ + for (void __user *_tmpptr = (void __user *) \ + __scoped_user_access_begin(mode, uptr, size, elbl); \ !done; done = true) \ for (CLASS(user_##mode##_access, scope)(_tmpptr); !done; done = true) \ /* Force modified pointer usage within the scope */ \ -- 2.49.0