From: Ravi Bangoria ravi.bangoria@amd.com
[ Upstream commit 3d47083b9ff46863e8374ad3bb5edb5e464c75f8 ]
IbsOpRip is recorded when IBS interrupt is triggered. But there is a skid from the time IBS interrupt gets triggered to the time the interrupt is presented to the core. Meanwhile processor would have moved ahead and thus IbsOpRip will be inconsistent with rsp and rbp recorded as part of the interrupt regs. This causes issues while unwinding stack using the ORC unwinder as it needs consistent rip, rsp and rbp. Fix this by using rip from interrupt regs instead of IbsOpRip for stack unwinding.
Fixes: ee9f8fce99640 ("x86/unwind: Add the ORC unwinder") Reported-by: Dmitry Monakhov dmtrmonakhov@yandex-team.ru Suggested-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Ravi Bangoria ravi.bangoria@amd.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20220429051441.14251-1-ravi.bangoria@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/events/amd/ibs.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c index b7baaa973317..2e930d8c04d9 100644 --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -312,6 +312,16 @@ static int perf_ibs_init(struct perf_event *event) hwc->config_base = perf_ibs->msr; hwc->config = config;
+ /* + * rip recorded by IbsOpRip will not be consistent with rsp and rbp + * recorded as part of interrupt regs. Thus we need to use rip from + * interrupt regs while unwinding call stack. Setting _EARLY flag + * makes sure we unwind call-stack before perf sample rip is set to + * IbsOpRip. + */ + if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) + event->attr.sample_type |= __PERF_SAMPLE_CALLCHAIN_EARLY; + return 0; }
@@ -683,6 +693,14 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs) data.raw = &raw; }
+ /* + * rip recorded by IbsOpRip will not be consistent with rsp and rbp + * recorded as part of interrupt regs. Thus we need to use rip from + * interrupt regs while unwinding call stack. + */ + if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) + data.callchain = perf_callchain(event, iregs); + throttle = perf_event_overflow(event, &data, ®s); out: if (throttle) {