From: Ravi Bangoria <ravi.bangoria@amd.com>

Date: Fri, 29 Apr 2022 10:44:41 +0530

Subject: perf/amd/ibs: Use interrupt regs ip for stack unwinding

Git-commit: 3d47083b9ff46863e8374ad3bb5edb5e464c75f8

Patch-mainline: v5.19-rc1

References: jsc#PED-1755

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: Tony Jones <tonyj@suse.de>

---

 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 9739019d4b67..11e8b493e015 100644

--- a/arch/x86/events/amd/ibs.c

+++ b/arch/x86/events/amd/ibs.c

@@ -304,6 +304,16 @@ 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;

 }

@@ -687,6 +697,14 @@ 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) {