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Groups > linux.kernel > #1627605
| From | Dave Hansen <dave.hansen@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space |
| Date | 2017-04-20 17:50 +0200 |
| Message-ID | <tymvg-2j8-11@gated-at.bofh.it> (permalink) |
| References | <ttgqu-1dQ-7@gated-at.bofh.it> <txgUV-2mc-15@gated-at.bofh.it> <tyj4m-kL-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 04/20/2017 05:08 AM, Joerg Roedel wrote: >> do_mpx_bt_fault() can fail for a bunch of reasons: >> * unexpected or invalid value in BNDCSR >> * out of memory (physical or virtual) >> * unresolvable fault walking/filling bounds tables >> * !valid and non-empty bad entry in the bounds tables >> >> This will end up sending a signal that *looks* like a X86_TRAP_BR for >> all of those, including those that are not really bounds-related, like >> unresolvable faults. We also don't populate enough information in the >> siginfo that gets delivered for userspace to resolve the fault. >> >> I'm not sure this patch is the right thing. > > The problem is, without this patch the trap_nr reported to user-space is > 0, which maps to divide-by-zero. I think this is wrong, and since all > failure cases from do_mpx_bt_fault() can only happen in the #BR > exception handler, I think that reporting X86_TRAP_BR for all failure > cases is the right thing to do. Urg, that does sound bogus. How about doing X86_TRAP_PF? That would at least be consistent with SIGBUS, which is probably the closest thing to a generic error code that we have.
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Re: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Dave Hansen <dave.hansen@linux.intel.com> - 2017-04-17 17:40 +0200
Re: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Joerg Roedel <jroedel@suse.de> - 2017-04-20 14:10 +0200
Re: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Dave Hansen <dave.hansen@linux.intel.com> - 2017-04-20 17:50 +0200
Re: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Joerg Roedel <jroedel@suse.de> - 2017-04-21 14:20 +0200
Re: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Dave Hansen <dave.hansen@linux.intel.com> - 2017-04-21 16:40 +0200
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