From: Arnd Bergmann
Sent: 16 February 2022 13:13
These two architectures implement 8-byte get_user() through
a memcpy() into a four-byte variable, which won't fit.
Use a temporary 64-bit variable instead here, and use a double
cast the way that risc-v and openrisc do to avoid compile-time
warnings.
...
case 4: \
- __get_user_asm("lw", (ptr), __gu_val, __gu_err); \
+ __get_user_asm("lw", (ptr), x, __gu_err); \
break; \
- case 8: \
- __gu_err = __copy_from_user(&__gu_val, ptr, 8); \
- if (__gu_err) \
- __gu_err = -EFAULT; \
+ case 8: { \
+ __u64 __x = 0; \
+ __gu_err = raw_copy_from_user(&__x, ptr, 8) ? \
+ -EFAULT : 0; \
+ (x) = (typeof(x))(typeof((x) - (x)))__x; \
break; \
Wouldn't it be better to just fetch two 32bit values:
Something like (for LE - nios2 is definitely LE:
__u32 val_lo, val_hi;
__get_user_asm("lw", (ptr), val_lo, __gu_err);
__get_user_asm("lw", (ptr) + 4, val_hi, __gu_err);
x = val_lo | val_hi << 32;
break;
David
-
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