linux-kernel - [PATCH 4.14 087/105] perf/x86/amd/ibs: Fix reading of the IBS OpData register and thus precise RIP validity

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Date:   Mon, 11 Nov 2019 19:28:57 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kim Phillips <kim.phillips@....com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Jiri Olsa <jolsa@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vince Weaver <vincent.weaver@...ne.edu>,
        Ingo Molnar <mingo@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 087/105] perf/x86/amd/ibs: Fix reading of the IBS OpData register and thus precise RIP validity

From: Kim Phillips <kim.phillips@....com>

[ Upstream commit 317b96bb14303c7998dbcd5bc606bd8038fdd4b4 ]

The loop that reads all the IBS MSRs into *buf stopped one MSR short of
reading the IbsOpData register, which contains the RipInvalid status bit.

Fix the offset_max assignment so the MSR gets read, so the RIP invalid
evaluation is based on what the IBS h/w output, instead of what was
left in memory.

Signed-off-by: Kim Phillips <kim.phillips@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Fixes: d47e8238cd76 ("perf/x86-ibs: Take instruction pointer from ibs sample")
Link: https://lkml.kernel.org/r/20191023150955.30292-1-kim.phillips@amd.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/events/amd/ibs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 7a86fbc07ddc1..4deecdb26ab30 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -625,7 +625,7 @@ fail:
 	if (event->attr.sample_type & PERF_SAMPLE_RAW)
 		offset_max = perf_ibs->offset_max;
 	else if (check_rip)
-		offset_max = 2;
+		offset_max = 3;
 	else
 		offset_max = 1;
 	do {
-- 
2.20.1