s390/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.

S390 is not affected for unsafe_*_user() as it uses its own local label
already, but __get/put_kernel_nofault() lack that.

Rename them to arch_*_kernel_nofault() which makes the generic uaccess
header wrap it with a local label that makes both compilers emit correct
code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://patch.msgid.link/20251027083745.483079889@linutronix.de

diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index 3e5b8b67705712a473e0df00221b49e9aa4b21fa..c5e02addcd67f1abef51b41c0e6c0837eb7f57f7 100644 (file)
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -468,8 +468,8 @@ do {                                                                        \
 
 #endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT && CONFIG_CC_HAS_ASM_AOR_FORMAT_FLAGS */
 
-#define __get_kernel_nofault __mvc_kernel_nofault
-#define __put_kernel_nofault __mvc_kernel_nofault
+#define arch_get_kernel_nofault __mvc_kernel_nofault
+#define arch_put_kernel_nofault __mvc_kernel_nofault
 
 void __cmpxchg_user_key_called_with_bad_pointer(void);