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

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Message-ID: <176173345142.2601451.2122580905143496385.tip-bot2@tip-bot2>
Date: Wed, 29 Oct 2025 10:24:11 -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] riscv/uaccess: Use unsafe wrappers for ASM GOTO

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

Commit-ID:     6de388be01ff9399789da58e5935ed9dac88bc4a
Gitweb:        https://git.kernel.org/tip/6de388be01ff9399789da58e5935ed9dac88bc4a
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Mon, 27 Oct 2025 09:43:50 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 29 Oct 2025 11:07:09 +01:00

riscv/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/20251027083745.419351819@linutronix.de
---
 arch/riscv/include/asm/uaccess.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index f5f4f7f..36bba67 100644
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -437,10 +437,10 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
 		__clear_user(untagged_addr(to), n) : n;
 }
 
-#define __get_kernel_nofault(dst, src, type, err_label)			\
+#define arch_get_kernel_nofault(dst, src, type, err_label)			\
 	__get_user_nocheck(*((type *)(dst)), (__force __user type *)(src), err_label)
 
-#define __put_kernel_nofault(dst, src, type, err_label)			\
+#define arch_put_kernel_nofault(dst, src, type, err_label)			\
 	__put_user_nocheck(*((type *)(src)), (__force __user type *)(dst), err_label)
 
 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
@@ -460,10 +460,10 @@ static inline void user_access_restore(unsigned long enabled) { }
  * We want the unsafe accessors to always be inlined and use
  * the error labels - thus the macro games.
  */
-#define unsafe_put_user(x, ptr, label)					\
+#define arch_unsafe_put_user(x, ptr, label)				\
 	__put_user_nocheck(x, (ptr), label)
 
-#define unsafe_get_user(x, ptr, label)	do {				\
+#define arch_unsafe_get_user(x, ptr, label)	do {			\
 	__inttype(*(ptr)) __gu_val;					\
 	__get_user_nocheck(__gu_val, (ptr), label);			\
 	(x) = (__force __typeof__(*(ptr)))__gu_val;			\