Merge tag 'mfd-next-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd

[linux-2.6-microblaze.git] / arch / x86 / include / asm / uaccess.h

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index f136595..c9fa7be 100644 (file)
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -208,16 +208,24 @@ extern void __put_user_nocheck_2(void);
 extern void __put_user_nocheck_4(void);
 extern void __put_user_nocheck_8(void);
 
+/*
+ * ptr must be evaluated and assigned to the temporary __ptr_pu before
+ * the assignment of x to __val_pu, to avoid any function calls
+ * involved in the ptr expression (possibly implicitly generated due
+ * to KASAN) from clobbering %ax.
+ */
 #define do_put_user_call(fn,x,ptr)                                     \
 ({                                                                     \
        int __ret_pu;                                                   \
+       void __user *__ptr_pu;                                          \
        register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX);           \
        __chk_user_ptr(ptr);                                            \
+       __ptr_pu = (ptr);                                               \
        __val_pu = (x);                                                 \
        asm volatile("call __" #fn "_%P[size]"                          \
                     : "=c" (__ret_pu),                                 \
                        ASM_CALL_CONSTRAINT                             \
-                    : "0" (ptr),                                       \
+                    : "0" (__ptr_pu),                                  \
                       "r" (__val_pu),                                  \
                       [size] "i" (sizeof(*(ptr)))                      \
                     :"ebx");                                           \