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Groups > linux.kernel > #1207868
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [GIT PULL] x86 fixes |
| Date | 2015-08-14 21:20 +0200 |
| Message-ID | <pXsGe-2Nt-7@gated-at.bofh.it> (permalink) |
| References | <pXhrr-3w7-1@gated-at.bofh.it> <pXrTQ-1Dj-17@gated-at.bofh.it> <pXsdb-206-13@gated-at.bofh.it> <pXsmS-2bn-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Aug 14, 2015 at 11:57 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Fri, Aug 14, 2015 at 11:46 AM, Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> I think it's only slightly broken.
>>
>> This bit:
>>
>> if ((FPU_CS & 4) != 4) { /* Must be in the LDT */
>> /* Can only handle segmented addressing via the LDT
>> for now, and it must be 16 bit */
>> printk("FPU emulator: Unsupported addressing mode\n");
>> math_abort(FPU_info, SIGILL);
>> }
>>
>> code_descriptor = FPU_get_ldt_descriptor(FPU_CS);
>>
>> is buggy, but no buggier than the old code.
>
> That code seems fine to me (and explicitly errors out when it's not in
> the LDT). FPU_CS is actually the CS selector value.
>
> So testing that for being in the LDT by checking bit #2, and then
> using FPU_get_ldt_descriptor() on it actually seems *correct*.
>
By "buggy" I meant that it aborted if it was in the GDT but wasn't
flat. This'll break if anyone does an emulated FP op on TLS data.
--Andy
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[GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-14 09:20 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 20:30 +0200
Re: [GIT PULL] x86 fixes Andy Lutomirski <luto@amacapital.net> - 2015-08-14 20:50 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 21:00 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 21:10 +0200
Re: [GIT PULL] x86 fixes Andy Lutomirski <luto@amacapital.net> - 2015-08-14 21:20 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 21:40 +0200
Re: [GIT PULL] x86 fixes Andy Lutomirski <luto@amacapital.net> - 2015-08-14 21:20 +0200
Re: [GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-17 10:10 +0200
Re: [GIT PULL] x86 fixes Denys Vlasenko <dvlasenk@redhat.com> - 2015-08-17 13:00 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-17 19:00 +0200
Re: [GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-18 10:00 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-17 18:50 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-17 19:00 +0200
Re: [GIT PULL] x86 fixes Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-17 19:20 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-18 00:20 +0200
Re: [GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-19 08:00 +0200
Re: [GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-19 08:20 +0200
Re: [GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-19 09:00 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-19 12:10 +0200
Re: [GIT PULL] x86 fixes Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2015-08-18 01:50 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-17 23:10 +0200
Re: [GIT PULL] x86 fixes Andy Lutomirski <luto@amacapital.net> - 2015-08-18 02:00 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-18 02:10 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-18 02:10 +0200
Re: [GIT PULL] x86 fixes Andy Lutomirski <luto@amacapital.net> - 2015-08-18 02:20 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-18 08:00 +0200
Re: [GIT PULL] x86 fixes "H. Peter Anvin" <hpa@zytor.com> - 2015-08-18 08:10 +0200
Re: [GIT PULL] x86 fixes Ingo Molnar <mingo@kernel.org> - 2015-08-18 10:00 +0200
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