Commit 0988ea18 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027083745.419351819@linutronix.de
parent 5002dd53

arch/riscv/include/asm/uaccess.h

+4 −4
Original line number Diff line number Diff line
@@ -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;			\