Commit 5002dd53 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

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: 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/20251027083745.356628509@linutronix.de
parent 14219398

arch/powerpc/include/asm/uaccess.h

+4 −4
Original line number Diff line number Diff line
@@ -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)