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Groups > linux.kernel > #1526959
| From | Linus Torvalds <torvalds@linux-foundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? |
| Date | 2016-11-21 19:10 +0100 |
| Message-ID | <sG1ct-4DY-3@gated-at.bofh.it> (permalink) |
| References | <sFpAe-4sJ-11@gated-at.bofh.it> <sFpTz-4UY-1@gated-at.bofh.it> <sFpTA-4UY-5@gated-at.bofh.it> <sFRd8-6zi-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Sun, Nov 20, 2016 at 11:13 PM, Ingo Molnar <mingo@kernel.org> wrote:
>
> So I have applied your fix that addresses the worst fallout directly:
>
> fc0e81b2bea0 x86/traps: Ignore high word of regs->cs in early_fixup_exception()
>
> ... but otherwise we might be better off zeroing out the high bits of segment
> registers stored on the stack, in all entry code pathways
Ugh.
I'd much rather we go back to just making the "cs" entry explicitly
16-bit, and have a separate padding entry, the way we used to long
long ago.
Or just rename it to something that you're not supposed to access
directly, and a helper accessor function that masks off the high bits.
The entry code-paths are *much* more critical than any of the few user
codepaths. Let's not add complexity to entry. Make the structure
actually reflect reality instead.
Linus
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What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Andy Lutomirski <luto@kernel.org> - 2016-11-20 03:00 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Brian Gerst <brgerst@gmail.com> - 2016-11-20 03:20 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Andy Lutomirski <luto@amacapital.net> - 2016-11-20 03:20 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Ingo Molnar <mingo@kernel.org> - 2016-11-21 08:30 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Linus Torvalds <torvalds@linux-foundation.org> - 2016-11-21 19:10 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? "H. Peter Anvin" <hpa@zytor.com> - 2016-11-21 19:40 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Linus Torvalds <torvalds@linux-foundation.org> - 2016-11-21 22:30 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Linus Torvalds <torvalds@linux-foundation.org> - 2016-11-21 23:30 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? hpa@zytor.com - 2016-11-21 23:30 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Andy Lutomirski <luto@amacapital.net> - 2016-11-24 18:20 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Ingo Molnar <mingo@kernel.org> - 2016-11-22 09:40 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Andy Lutomirski <luto@amacapital.net> - 2016-11-22 18:40 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Ingo Molnar <mingo@kernel.org> - 2016-11-23 10:00 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? hpa@zytor.com - 2016-11-21 07:00 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? "H. Peter Anvin" <hpa@zytor.com> - 2016-11-21 17:10 +0100
Re: What exactly do 32-bit x86 exceptions push on the stack in the CS slot? Linus Torvalds <torvalds@linux-foundation.org> - 2016-11-21 19:30 +0100
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