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Groups > linux.kernel > #1432187
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks |
| Date | 2016-06-27 19:40 +0200 |
| Message-ID | <rOIFP-3km-3@gated-at.bofh.it> (permalink) |
| References | (2 earlier) <rOGkF-1Xk-17@gated-at.bofh.it> <rOGul-20Y-9@gated-at.bofh.it> <rOGE1-24t-15@gated-at.bofh.it> <rOH73-2eF-1@gated-at.bofh.it> <rOIw9-3gD-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, Jun 27, 2016 at 10:28 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Mon, Jun 27, 2016 at 8:54 AM, Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> How about:
>>
>> tsk_stack = (unsigned long)task_stack_page(tsk);
>> if (regs->rsp <= tsk_stack + 7*8 && regs->rsp > tsk_stack - PAGE_SIZE) {
>
> I'm not at all convinced that regs->rsp will be all that reliable
> under a double-fault scenario either. I'd be more inclined to trusr
> cr2 than the register state.
>
> It's true that double faults can happen for *other* reasons entirely,
> and as such it's not clear that %cr2 is reliable either, but since
> this is all just about a printout, I'd rather go that way anyway.
Fair enough. The chance that we get #GP-in-#GP or similar while CR2
coincidentally points to the guard page is quite low. I'll add all
the details to the comment but I'll leave the code alone.
FWIW, the manual only says that CS and RIP are untrustworthy, not that
RSP is untrustworthy, but it doesn't specify *what* RSP would contain
anywhere I can find. I don't think this is important enough to start
harassing the Intel and AMD folks over.
--Andy
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[PATCH v4 00/29] virtually mapped stacks and thread_info cleanup Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 07/29] mm: Fix memcg stack accounting for sub-page stacks Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 24/29] x86/entry: Get rid of pt_regs_to_thread_info() Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
Re: [PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Borislav Petkov <bp@alien8.de> - 2016-07-02 19:30 +0200
Re: [PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-02 20:40 +0200
Re: [PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Borislav Petkov <bp@alien8.de> - 2016-07-03 11:50 +0200
Re: [PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Andy Lutomirski <luto@amacapital.net> - 2016-07-03 16:30 +0200
Re: [PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Borislav Petkov <bp@alien8.de> - 2016-07-03 20:50 +0200
[PATCH v4 12/29] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 06/29] mm: Track NR_KERNEL_STACK in KiB instead of number of stacks Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 14/29] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 26/29] sched: Allow putting thread_info into task_struct Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
[PATCH v4 08/29] dma-api: Teach the "DMA-from-stack" check about vmapped stacks Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:00 +0200
Re: [PATCH v4 08/29] dma-api: Teach the "DMA-from-stack" check about vmapped stacks Borislav Petkov <bp@alien8.de> - 2016-06-30 21:40 +0200
Re: [PATCH v4 08/29] dma-api: Teach the "DMA-from-stack" check about vmapped stacks Andy Lutomirski <luto@amacapital.net> - 2016-07-06 15:30 +0200
[PATCH v4 25/29] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 25/29] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski <luto@amacapital.net> - 2016-06-27 01:50 +0200
Re: [PATCH v4 25/29] um: Stop conflating task_struct::stack with thread_info Brian Gerst <brgerst@gmail.com> - 2016-06-27 01:50 +0200
[PATCH v4 22/29] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 22/29] x86/asm: Move 'status' from struct thread_info to struct thread_struct Brian Gerst <brgerst@gmail.com> - 2016-06-27 02:00 +0200
Re: [PATCH v4 22/29] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski <luto@amacapital.net> - 2016-06-27 02:30 +0200
Re: [PATCH v4 22/29] x86/asm: Move 'status' from struct thread_info to struct thread_struct Brian Gerst <brgerst@gmail.com> - 2016-06-27 02:40 +0200
Re: [PATCH v4 22/29] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski <luto@amacapital.net> - 2016-06-27 02:50 +0200
[PATCH v4 19/29] signal: Consolidate {TS,TLF}_RESTORE_SIGMASK code Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Brian Gerst <brgerst@gmail.com> - 2016-06-27 17:10 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Brian Gerst <brgerst@gmail.com> - 2016-06-27 17:20 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Andy Lutomirski <luto@amacapital.net> - 2016-06-27 17:30 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Andy Lutomirski <luto@amacapital.net> - 2016-06-27 18:00 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Brian Gerst <brgerst@gmail.com> - 2016-06-27 18:20 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Andy Lutomirski <luto@amacapital.net> - 2016-06-27 18:40 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Brian Gerst <brgerst@gmail.com> - 2016-06-27 19:10 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Brian Gerst <brgerst@gmail.com> - 2016-06-27 19:30 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Linus Torvalds <torvalds@linux-foundation.org> - 2016-06-27 19:30 +0200
Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Andy Lutomirski <luto@amacapital.net> - 2016-06-27 19:40 +0200
[PATCH v4 18/29] x86: Move addr_limit to thread_struct Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 17/29] x86: Move uaccess_err and sig_on_uaccess_err to thread_struct Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 03/29] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 23/29] kdb: Use task_cpu() instead of task_thread_info()->cpu Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 16/29] x86/mm: Improve stack-overflow #PF handling Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 20/29] x86/smp: Remove stack_smp_processor_id() Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
[PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 09:40 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad Herbert Xu <herbert@gondor.apana.org.au> - 2016-06-28 09:40 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 11:10 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad Herbert Xu <herbert@gondor.apana.org.au> - 2016-06-28 11:50 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 09:50 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 10:00 +0200
[PATCH v4 04/29] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 04/29] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Borislav Petkov <bp@alien8.de> - 2016-06-28 21:10 +0200
Re: [PATCH v4 04/29] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski <luto@amacapital.net> - 2016-06-28 21:10 +0200
[PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Marcel Holtmann <marcel@holtmann.org> - 2016-06-27 08:00 +0200
Re: [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Ingo Molnar <mingo@kernel.org> - 2016-06-27 11:00 +0200
Re: [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Marcel Holtmann <marcel@holtmann.org> - 2016-06-28 00:40 +0200
Re: [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Andy Lutomirski <luto@amacapital.net> - 2016-06-28 00:40 +0200
Re: [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Marcel Holtmann <marcel@holtmann.org> - 2016-07-04 20:00 +0200
Re: [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Andy Lutomirski <luto@amacapital.net> - 2016-07-06 15:20 +0200
[PATCH v4 21/29] x86/smp: Remove unnecessary initialization of thread_info::cpu Andy Lutomirski <luto@kernel.org> - 2016-06-27 00:10 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad Herbert Xu <herbert@gondor.apana.org.au> - 2016-06-28 10:00 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 11:00 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad Herbert Xu <herbert@gondor.apana.org.au> - 2016-06-28 11:50 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 12:10 +0200
Re: [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells <dhowells@redhat.com> - 2016-06-28 15:30 +0200
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