This patchset fixes a false negative report (ie, unreliable) from the ppc64 reliable stack unwinder, discussed here [1] when it may inadvertently trip over a stale exception marker left on the stack. The first two patches fix this bug. Nicolai's change clears the marker from the stack when an exception is finished. The next patch modifies the unwinder to only look for such on stack elements when the ABI guarantees that they will actually be initialized. The final two patches consist of code cleanups that Nicolai and I spotted during the development of the fixes. Testing included re-running the original test scenario (loading a livepatch module on ppc64le) on a 5.0.0-rc2 kernel as well as a RHEL-7 backport. I ran internal tests on the RHEL-7 backport and no new test failures were introduced. I believe that Nicolai has done the same with respect to the first patch. [1] https://lore.kernel.org/lkml/7f468285-b149-37e2-e782-c9e538b997a9@xxxxxxxxxx/ Joe Lawrence (3): powerpc/livepatch: relax reliable stack tracer checks for first-frame powerpc/livepatch: small cleanups in save_stack_trace_tsk_reliable() powerpc/livepatch: return -ERRNO values in save_stack_trace_tsk_reliable() Nicolai Stange (1): powerpc/64s: Clear on-stack exception marker upon exception return arch/powerpc/Kconfig | 2 +- arch/powerpc/kernel/entry_64.S | 7 +++ arch/powerpc/kernel/stacktrace.c | 74 +++++++++++++++++--------------- 3 files changed, 47 insertions(+), 36 deletions(-) -- 2.20.1
