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
