We have a problem on the 32bit kernel with __get_user()
for a 64bit value.
In arch/parisc/include/asm/uaccess.h we have
#define __get_user(x, ptr) \
({ \
register long __gu_err __asm__ ("r8") = 0; \
register long __gu_val; \
\
load_sr2(); \
switch (sizeof(*(ptr))) { \
case 1: __get_user_asm("ldb", ptr); break; \
case 2: __get_user_asm("ldh", ptr); break; \
case 4: __get_user_asm("ldw", ptr); break; \
case 8: LDD_USER(ptr); break; \
default: BUILD_BUG(); break; \
} \
\
(x) = (__force __typeof__(*(ptr))) __gu_val; \
__gu_err; \
})
The problem is, that on a 32bit kernel __gu_val is a 32bit ("long") variable,
but LDD_USER(ptr) returns a 64bit entity.
And since __gu_val is 32bit only, afterwards the (x) = __gu_val will
return a 32bit-truncated value too.
I'm not sure how this can be fixed. My latest approaches always ended
with lots of compiler warnings.
A testcase for this is the test_user_copy.ko kernel module (source
in lib/test_user_copy.c).
Any ideas?
Helge
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