From d09fbb327d670737ab40fd8bbb0765ae06b8b739 Mon Sep 17 00:00:00 2001 From: Russell King Date: Mon, 9 Jul 2018 15:22:45 +0100 Subject: ARM: use __inttype() in get_user() 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 Signed-off-by: Russell King --- arch/arm/include/asm/uaccess.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 0bf2347495f1..29fa6f3ea25a 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -84,6 +84,13 @@ static inline void set_fs(mm_segment_t fs) : "cc"); \ 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 @@ -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(); \ -- cgit