The existing __get_user() implementation does not support fetching
64 bit values on 32 bit x86. Implement this in a way that does not
generate any incorrect warnings as cautioned by Russell King. Test
code available at http://www.kvack.org/~bcrl/x86_32-get_user.tar .
Signed-off-by: Benjamin LaHaise <b...@kvack.org>
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index a4a30e4..2d0607a 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -333,7 +333,23 @@ do {
\
} while (0)
#ifdef CONFIG_X86_32
-#define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad()
+#define __get_user_asm_u64(x, addr, err, errret) \
+ asm volatile(ASM_STAC "\n" \
+ "1: movl %2,%%eax\n" \
+ "2: movl %3,%%edx\n" \
+ "3: " ASM_CLAC "\n" \
+ ".section .fixup,\"ax\"\n" \
+ "4: mov %4,%0\n" \
+ " xorl %%eax,%%eax\n" \
+ " xorl %%edx,%%edx\n" \
+ " jmp 3b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE(1b, 4b) \
+ _ASM_EXTABLE(2b, 4b) \
+ : "=r" (err), "=A"(x) \
+ : "m" (__m(addr)), "m" __m(((u32 *)(addr)) + 1), \
+ "i" (errret), "0" (err))
+
#define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad()
#else
#define __get_user_asm_u64(x, ptr, retval, errret) \
@@ -420,11 +436,20 @@ do {
\
#define __get_user_nocheck(x, ptr, size) \
({ \
int __gu_err; \
- unsigned long __gu_val; \
- __uaccess_begin(); \
- __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
- __uaccess_end(); \
- (x) = (__force __typeof__(*(ptr)))__gu_val; \
+ if (size == 8) { \
+ unsigned long __gu_val[2]; \
+ __gu_err = 0; \
+ __uaccess_begin(); \
+ __get_user_asm_u64(__gu_val, ptr, __gu_err, -EFAULT); \
+ __uaccess_end(); \
+ (x) = *(__force __typeof__((ptr)))__gu_val; \
+ } else { \
+ unsigned long __gu_val; \
+ __uaccess_begin(); \
+ __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
+ __uaccess_end(); \
+ (x) = (__force __typeof__(*(ptr)))__gu_val; \
+ } \
__builtin_expect(__gu_err, 0); \
})
--
"Thought is the essence of where you are now."
