Messages in this thread | | | From | Mark Rutland <> | Subject | [PATCH 0/3] kcov: fix unexpected faults | Date | Fri, 4 May 2018 14:55:32 +0100 |
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Hi,
These patches fix a few issues where KCOV code could trigger recursive faults, discovered while debugging a patch enabling KCOV for arch/arm:
* On CONFIG_PREEMPT kernels, there's a small race window where __sanitizer_cov_trace_pc() can see a bogus kcov_area.
* Lazy faulting of the vmalloc area can cause mutual recursion between fault handling code and __sanitizer_cov_trace_pc().
* During the context switch, switching the mm can cause the kcov_area to be transiently unmapped.
These are prerequisites for enabling KCOV on arm, but the issues themsevles are generic -- we just happen to avoid them by chance rather than design on x86-64 and arm64.
I've tested this on arm atop of v4.17-rc3, with KCOV enabled.
Thanks, Mark.
Mark Rutland (3): kcov: ensure irq code sees a valid area kcov: prefault the kcov_area sched/core / kcov: avoid kcov_area during task switch
include/linux/kcov.h | 14 ++++++++++++++ include/linux/sched.h | 2 +- kernel/kcov.c | 17 +++++++++++++++-- kernel/sched/core.c | 4 ++++ 4 files changed, 34 insertions(+), 3 deletions(-)
-- 2.11.0
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