virtio wants to write bitwise types to userspace using put_user.
At the moment this triggers sparse errors, since the value is passed
through an integer.
For example:
__le32 __user *p;
__le32 x;
put_user(x, p);
is safe, but currently triggers a sparse warning on tile.
The reason has to do with this code:
__typeof((x)-(x))
which seems to be a way to force check for an integer type.
Since this is part of __put_user_8 which is only ever used
for unsigned and signed char types, this seems unnecessary -
I also note that no other architecture has such protections.
Fix that up using __force u64 cast.
Note: this does not suppress any useful sparse checks since
the original merely casted x to typeof(x-x).
Tile currently does not trigger sparse warnings when get_user
causes an illegal assignment across bitwise types.
This patch does not attempt to fix this.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
arch/tile/include/asm/uaccess.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/tile/include/asm/uaccess.h b/arch/tile/include/asm/uaccess.h
index b6cde32..22cffa1 100644
--- a/arch/tile/include/asm/uaccess.h
+++ b/arch/tile/include/asm/uaccess.h
@@ -246,7 +246,7 @@ extern int __get_user_bad(void)
#define __put_user_4(x, ptr, ret) __put_user_asm(sw, x, ptr, ret)
#define __put_user_8(x, ptr, ret) \
({ \
- u64 __x = (__typeof((x)-(x)))(x); \
+ u64 __x = (__force u64)(x); \
int __lo = (int) __x, __hi = (int) (__x >> 32); \
asm volatile("1: { sw %1, %2; addi %0, %1, 4 }\n" \
"2: { sw %0, %3; movei %0, 0 }\n" \
--
MST
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