On 07.02.2025 22:06, Josh Poimboeuf wrote:
On Wed, Feb 05, 2025 at 10:47:58AM +0100, Jens Remus wrote:
UNSAFE_GET_USER_INC(ra_off, cur, offset_size, Efault);
With offset_size=1 expands into:
__UNSAFE_GET_USER_INC(/*to=*/ra_off, /*from=*cur, /*type=*/u8,
/*label=*/Efault);
Expands into:
{
u8 __to;
unsafe_get_user(__to, (u8 __user *)cur, Efault);
cur += sizeof(__to);
ra_off = (typeof(ra_off))__to;
}
The issue is that on the last line __to is u8 instead of s8 and thus
u8 gets casted to s32, which is performed without sign extension. __to
would need to be s8 or get casted to s8 for sign extension to take
place.
Ah, I get it now, thanks for spelling that out for me.
Here's what I have at the moment:
Thanks! Using your new UNSAFE_GET_USER_INC() in all places works great
on s390 when resolving the duplicate macro names (see below).
#define __UNSAFE_GET_USER_INC(to, from, type, label) \
({ \
type __to; \
unsafe_get_user(__to, (type __user *)from, label); \
from += sizeof(__to); \
to = __to; \
})
#define __UNSAFE_GET_USER_INC(to, from, size, label, u_or_s) \
That does not compile. One of the macros needs to be renamed.
CC kernel/unwind/sframe.o
kernel/unwind/sframe.c:141:9: warning: "__UNSAFE_GET_USER_INC" redefined
141 | #define __UNSAFE_GET_USER_INC(to, from, size, label, u_or_s)
\
| ^~~~~~~~~~~~~~~~~~~~~
kernel/unwind/sframe.c:133:9: note: this is the location of the previous
definition
133 | #define __UNSAFE_GET_USER_INC(to, from, type, label)
\
| ^~~~~~~~~~~~~~~~~~~~~
({ \
switch (size) { \
case 1: \
__UNSAFE_GET_USER_INC(to, from, u_or_s##8, label); \
break; \
case 2: \
__UNSAFE_GET_USER_INC(to, from, u_or_s##16, label); \
break; \
case 4: \
__UNSAFE_GET_USER_INC(to, from, u_or_s##32, label); \
break; \
default: \
dbg_sec_uaccess("%d: bad unsafe_get_user() size %u\n", \
__LINE__, size); \
return -EFAULT; \
} \
})
#define UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label) \
__UNSAFE_GET_USER_INC(to, from, size, label, u)
#define UNSAFE_GET_USER_SIGNED_INC(to, from, size, label) \
__UNSAFE_GET_USER_INC(to, from, size, label, s)
#define UNSAFE_GET_USER_INC(to, from, size, label)
\
_Generic(to,
\
u8: UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label),
\
u16: UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label),
\
u32: UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label),
\
s8: UNSAFE_GET_USER_SIGNED_INC(to, from, size, label),
\
s16: UNSAFE_GET_USER_SIGNED_INC(to, from, size, label),
\
s32: UNSAFE_GET_USER_SIGNED_INC(to, from, size, label))
Regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
+49-7031-16-1128 Office
jre...@de.ibm.com
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