linux-kernel - [PATCH V2 1/1] perf/x86: filter branches for PEBS event

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1427467105-9260-1-git-send-email-kan.liang@intel.com>
Date:	Fri, 27 Mar 2015 10:38:25 -0400
From:	kan.liang@...el.com
To:	a.p.zijlstra@...llo.nl
Cc:	eranian@...gle.com, andi@...stfloor.org,
	linux-kernel@...r.kernel.org, Kan Liang <kan.liang@...el.com>
Subject: [PATCH V2 1/1] perf/x86: filter branches for PEBS event

From: Kan Liang <kan.liang@...el.com>

For supporting Intel LBR branches filtering, Intel LBR sharing logic
mechanism is introduced from commit b36817e88630 ("perf/x86: Add Intel
LBR sharing logic"). It modifies __intel_shared_reg_get_constraints to
config lbr_sel, which is finally used to set LBR_SELECT.
However, the intel_shared_regs_constraints is called after
intel_pebs_constraints. The PEBS event will return immediately after
intel_pebs_constraints. So it's impossible to filter branches for PEBS
event.

This patch move intel_shared_regs_constraints ahead of
intel_pebs_constraints.
We can safely do that because the intel_shared_regs_constraints only
returns emptyconstraint if its rejecting the event, otherwise it returns
NULL such that we continue calling intel_pebs_constraints and
x86_get_event_constraint.

Signed-off-by: Kan Liang <kan.liang@...el.com>
---

Changes since V1:
 - Move all shared regs ahead of intel_pebs_constraints
 - Modify the description and quote Peter's comments.

 arch/x86/kernel/cpu/perf_event_intel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 9f1dd18..83bee99 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1635,11 +1635,11 @@ intel_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event
 	if (c)
 		return c;

-	c = intel_pebs_constraints(event);
+	c = intel_shared_regs_constraints(cpuc, event);
 	if (c)
 		return c;

-	c = intel_shared_regs_constraints(cpuc, event);
+	c = intel_pebs_constraints(event);
 	if (c)
 		return c;

-- 
1.8.3.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/