Messages in this thread | | | Date | Wed, 5 May 2021 09:48:22 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v4 3/4] x86/uaccess: Use pointer masking to limit uaccess speculation |
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On Wed, May 05, 2021 at 03:25:42PM +0100, Mark Rutland wrote: > On arm64 we needed to have a sequence here because the addr_limit used > to be variable, but now that we've removed set_fs() and split the > user/kernel access routines we could simplify that to an AND with an > immediate mask to force all pointers into the user half of the address > space. IIUC x86_64 could do the same, and I think that was roughly what > David was suggesting.
True. On 64-bit arches it might be as simple as just clearing the most-significant bit.
-- Josh
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