Commit 43cc54d8 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

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: 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>
Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Link: https://patch.msgid.link/20251027083745.483079889@linutronix.de
parent 0988ea18

arch/s390/include/asm/uaccess.h

+2 −2
Original line number Diff line number Diff line
@@ -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);