Messages in this thread | | | Subject | Re: [PATCH] x86_32: add support for 64 bit __get_user() | From | "H. Peter Anvin" <> | Date | Wed, 9 Mar 2016 10:22:50 -0800 |
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On 03/09/2016 09:50 AM, Benjamin LaHaise wrote: > On Wed, Mar 09, 2016 at 09:36:30AM -0800, H. Peter Anvin wrote: >> On March 9, 2016 9:22:25 AM PST, Benjamin LaHaise <bcrl@kvack.org> wrote: >>> The existing __get_user() implementation does not support fetching >>> 64 bit values on 32 bit x86. Implement this in a way that does not >>> generate any incorrect warnings as cautioned by Russell King. Test >>> code available at http://www.kvack.org/~bcrl/x86_32-get_user.tar . > ... >> Weird. I could swear we had already fixed this a few years ago. > > That surprised me as well, but Russell raised the fact that the approaches > previously tried on 32 bit architectures had caused various incorrect > compiler warnings for certain obscure cases -- see the code in test_module.c > in that URL that Russell provided to demonstrate the problem across all the > corner cases.
Oh, I see... I implemented it for put but not get... weird. You may want to look at the __inttype() macro defined earlier in this file; it might be useful.
I presume you have already seen:
>> fs/select.c:710: Error: operand type mismatch for `movq' >> fs/select.c:714: Error: incorrect register `%cx' used with `q' suffix fs/select.c:711: Error: operand type mismatch for `movq' >> fs/select.c:715: Error: incorrect register `%si' used with `q' suffix -- fs/aio.c: Assembler messages: >> fs/aio.c:1606: Error: operand type mismatch for `movq' >> fs/aio.c:1610: Error: incorrect register `%si' used with `q' suffix
... which implies it used 16-bit registers for 64-bit operations when compiling for 64 bits.
-hpa
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