linux-kernel - [tip: core/rseq] powerpc/uaccess: Use unsafe wrappers for ASM GOTO

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Message-ID: <176173345265.2601451.7918862756893080866.tip-bot2@tip-bot2>
Date: Wed, 29 Oct 2025 10:24:12 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: core/rseq] powerpc/uaccess: Use unsafe wrappers for ASM GOTO

The following commit has been merged into the core/rseq branch of tip:

Commit-ID:     ea832a74a28cd09137c07f206557f7002e32b1f1
Gitweb:        https://git.kernel.org/tip/ea832a74a28cd09137c07f206557f7002e32b1f1
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Mon, 27 Oct 2025 09:43:48 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 29 Oct 2025 11:07:08 +01:00

powerpc/uaccess: Use unsafe wrappers for ASM GOTO

ASM GOTO is miscompiled by GCC when it is used inside a auto cleanup scope:

bool foo(u32 __user *p, u32 val)
{
	scoped_guard(pagefault)
		unsafe_put_user(val, p, efault);
	return true;
efault:
	return false;
}

It ends up leaking the pagefault disable counter in the fault path. clang
at least fails the build.

Rename unsafe_*_user() to arch_unsafe_*_user() which makes the generic
uaccess header wrap it with a local label that makes both compilers emit
correct code. Same for the kernel_nofault() variants.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Link: https://patch.msgid.link/20251027083745.356628509@linutronix.de
---
 arch/powerpc/include/asm/uaccess.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 4f5a46a..784a00e 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -451,7 +451,7 @@ user_write_access_begin(const void __user *ptr, size_t len)
 #define user_write_access_begin	user_write_access_begin
 #define user_write_access_end		prevent_current_write_to_user
 
-#define unsafe_get_user(x, p, e) do {					\
+#define arch_unsafe_get_user(x, p, e) do {			\
 	__long_type(*(p)) __gu_val;				\
 	__typeof__(*(p)) __user *__gu_addr = (p);		\
 								\
@@ -459,7 +459,7 @@ user_write_access_begin(const void __user *ptr, size_t len)
 	(x) = (__typeof__(*(p)))__gu_val;			\
 } while (0)
 
-#define unsafe_put_user(x, p, e) \
+#define arch_unsafe_put_user(x, p, e)				\
 	__put_user_size_goto((__typeof__(*(p)))(x), (p), sizeof(*(p)), e)
 
 #define unsafe_copy_from_user(d, s, l, e) \
@@ -504,11 +504,11 @@ do {									\
 		unsafe_put_user(*(u8*)(_src + _i), (u8 __user *)(_dst + _i), e); \
 } while (0)
 
-#define __get_kernel_nofault(dst, src, type, err_label)			\
+#define arch_get_kernel_nofault(dst, src, type, err_label)		\
 	__get_user_size_goto(*((type *)(dst)),				\
 		(__force type __user *)(src), sizeof(type), err_label)
 
-#define __put_kernel_nofault(dst, src, type, err_label)			\
+#define arch_put_kernel_nofault(dst, src, type, err_label)		\
 	__put_user_size_goto(*((type *)(src)),				\
 		(__force type __user *)(dst), sizeof(type), err_label)