4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx> Commit d09fbb327d670737ab40fd8bbb0765ae06b8b739 upstream. Borrow the x86 implementation of __inttype() to use in get_user() to select an integer type suitable to temporarily hold the result value. This is necessary to avoid propagating the volatile nature of the result argument, which can cause the following warning: lib/iov_iter.c:413:5: warning: optimization may eliminate reads and/or writes to register variables [-Wvolatile-register-var] Acked-by: Mark Rutland <mark.rutland@xxxxxxx> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx> Signed-off-by: David A. Long <dave.long@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm/include/asm/uaccess.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -85,6 +85,13 @@ static inline void set_fs(mm_segment_t f flag; }) /* + * This is a type: either unsigned long, if the argument fits into + * that type, or otherwise unsigned long long. + */ +#define __inttype(x) \ + __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) + +/* * Single-value transfer routines. They automatically use the right * size if we just have the right pointer type. Note that the functions * which read from user space (*get_*) need to take care not to leak @@ -153,7 +160,7 @@ extern int __get_user_64t_4(void *); ({ \ unsigned long __limit = current_thread_info()->addr_limit - 1; \ register const typeof(*(p)) __user *__p asm("r0") = (p);\ - register typeof(x) __r2 asm("r2"); \ + register __inttype(x) __r2 asm("r2"); \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \ unsigned int __ua_flags = uaccess_save_and_enable(); \