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Groups > linux.kernel > #1289835
| From | Jeff Merkey <linux.mdb@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2 1/1] Fix int1 recursion when no perf_bp_event is registeredy |
| Date | 2015-12-11 20:10 +0100 |
| Message-ID | <qEBeN-7o-13@gated-at.bofh.it> (permalink) |
| References | <qE3G9-2Ub-5@gated-at.bofh.it> <qEeBz-1xO-5@gated-at.bofh.it> <qEeLg-1Qp-3@gated-at.bofh.it> <qEgtI-2KO-23@gated-at.bofh.it> <qEqW6-1rK-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
One thing I noticed in this section of code:
/* Handle all the breakpoints that were triggered */
for (i = 0; i < HBP_NUM; ++i) {
if (likely(!(dr6 & (DR_TRAP0 << i))))
continue;
... snip ...
if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE)
args->regs->flags |= X86_EFLAGS_RF;
rcu_read_unlock();
}
Whoever wrote this loop did not seem to understand have observed the
code path in action on intel hardware. There is NEVER a case I have
seen when the hardware sends multiple breakpoint statuses through dr6,
they are sent one at a time. So the rolling check through all the
status bits is pointless since only one breakpoint will be reported by
the hardware at a time. This is not to say that someone in the future
might may change it, but these interrupts are delivered one by one in
order and if there are duplicates (like a read/write breakpoint set at
the same address as an execute breakpoint.
Does anyone know why it was coded this way because its flat wrong.
Jeff
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[PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 08:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Thomas Gleixner <tglx@linutronix.de> - 2015-12-10 20:00 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Andy Lutomirski <luto@amacapital.net> - 2015-12-10 20:10 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Jiri Olsa <jolsa@redhat.com> - 2015-12-10 20:30 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Borislav Petkov <bp@alien8.de> - 2015-12-10 20:30 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Thomas Gleixner <tglx@linutronix.de> - 2015-12-10 22:00 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Andy Lutomirski <luto@amacapital.net> - 2015-12-10 22:10 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Thomas Gleixner <tglx@linutronix.de> - 2015-12-10 22:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 22:30 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 22:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Ingo Molnar <mingo@kernel.org> - 2015-12-14 09:10 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-14 09:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-14 09:30 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Ingo Molnar <mingo@kernel.org> - 2015-12-14 10:30 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-14 19:00 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Andy Lutomirski <luto@amacapital.net> - 2015-12-14 19:00 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-14 19:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-14 19:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 22:20 +0100
Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 23:30 +0100
Re: [PATCH v2 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-11 09:10 +0100
Re: [PATCH v2 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-11 20:10 +0100
Re: [PATCH v2 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-14 00:20 +0100
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