Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 29 Sep 2014 13:29:22 -0700 | Subject | Re: [PATCH] x86 : Ensure X86_FLAGS_NT is cleared on syscall entry |
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On Mon, Sep 29, 2014 at 1:01 PM, H. Peter Anvin <hpa@zytor.com> wrote: > On 09/29/2014 12:57 PM, Thomas Gleixner wrote: >> >>> I think we should mask the bit anyway. >> >> I tend to disagree. If we clear it there we need to consequentely >> audit ALL other possibilites and if there are any we need to clear the >> bit there as well. Just to make buggy user space happy? >> > > The entry options into the kernel are: interrupt/exception (already > known to be OK),
> SYSENTER32,
I don't immediately see how to fix that without adding overhead. Maybe do it in CLEAR_RREGS? This won't do any good if EFI ever starts using IRET, though. We could suck it up and fix it on entry, adding maybe ten cycles (wild guess).
> SYSCALL32
This should happen for free if we fix SYSCALL64, I think.
Also, I thought entry_64.S was a mess. Eww, ia32entry.S.
I can try to write the patch later today. But I don't want to touch the actual 32-bit kernel code -- I'll stick to the 64-bit native and compat stuff, thanks.
--Andy
and SYSCALL64. It is not too > much to work through those issues, I don't think. > > -hpa >
-- Andy Lutomirski AMA Capital Management, LLC
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