Messages in this thread Patch in this message | | | Date | Mon, 15 Dec 2014 11:23:11 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 03/18] arm64/uaccess: fix sparse errors |
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On Mon, Dec 15, 2014 at 11:17:16AM +0000, Will Deacon wrote: > On Sun, Dec 14, 2014 at 04:52:09PM +0000, Michael S. Tsirkin wrote: > > virtio wants to read bitwise types from userspace using get_user. At the > > moment this triggers sparse errors, since the value is passed through an > > integer. > > > > Fix that up using __force. > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > --- > > arch/arm64/include/asm/uaccess.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h > > index 3bf8f4e..8d66bcf 100644 > > --- a/arch/arm64/include/asm/uaccess.h > > +++ b/arch/arm64/include/asm/uaccess.h > > @@ -147,7 +147,7 @@ do { \ > > default: \ > > BUILD_BUG(); \ > > } \ > > - (x) = (__typeof__(*(ptr)))__gu_val; \ > > + (x) = (__force __typeof__(*(ptr)))__gu_val; \ > > } while (0) > > > > #define __get_user(x, ptr) \ > > Acked-by: Will Deacon <will.deacon@arm.com>
This also means you can do stuff like:
u32 *p; __le32 v;
err = get_user(p, v);
which is not right. Both the dereferenced pointer type and the destination type should be compatible, and if one is a bitwise type but the other isn't, that seems like a valid case to warn.
I don't see any use of get_user() in drivers/virtio in mainline, so I can't check further.
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