linux-kernel - [PATCH 3.16 095/136] perf/x86/amd/ibs: Fix reading of the IBS OpData register and thus precise RIP validity

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Message-ID: <lsq.1576543535.546437391@decadent.org.uk>
Date:   Tue, 17 Dec 2019 00:47:09 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Arnaldo Carvalho de Melo" <acme@...nel.org>,
        "Stephane Eranian" <eranian@...gle.com>,
        "Kim Phillips" <kim.phillips@....com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Ingo Molnar" <mingo@...nel.org>, "Jiri Olsa" <jolsa@...hat.com>,
        "Mark Rutland" <mark.rutland@....com>,
        "Alexander Shishkin" <alexander.shishkin@...ux.intel.com>,
        "Arnaldo Carvalho de Melo" <acme@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Namhyung Kim" <namhyung@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Borislav Petkov" <bp@...en8.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Vince Weaver" <vincent.weaver@...ne.edu>
Subject: [PATCH 3.16 095/136] perf/x86/amd/ibs: Fix reading of the IBS
 OpData register and thus precise RIP validity

3.16.80-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit 317b96bb14303c7998dbcd5bc606bd8038fdd4b4 upstream.

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>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/cpu/perf_event_amd_ibs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
@@ -555,7 +555,7 @@ static int perf_ibs_handle_irq(struct pe
 	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 {