linux-kernel - [PATCH V4 06/16] perf, core: always switch pmu specific data during context switch

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

Message-Id: <1404118253-19532-7-git-send-email-zheng.z.yan@intel.com>
Date:	Mon, 30 Jun 2014 16:50:43 +0800
From:	"Yan, Zheng" <zheng.z.yan@...el.com>
To:	linux-kernel@...r.kernel.org
Cc:	a.p.zijlstra@...llo.nl, mingo@...nel.org, acme@...radead.org,
	eranian@...gle.com, andi@...stfloor.org,
	"Yan, Zheng" <zheng.z.yan@...el.com>
Subject: [PATCH V4 06/16] perf, core: always switch pmu specific data during context switch

If two tasks were both forked from the same parent task, Events in
their perf task contexts can be the same. Perf core may leave out
switching the perf event contexts.

Previous patch inroduces pmu specific data. The data is for saving
the LBR stack, it is task specific. So we need to switch the data
even when context switch is optimized out.

Signed-off-by: Yan, Zheng <zheng.z.yan@...el.com>
---
 kernel/events/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9f35d64..a856813 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2339,6 +2339,7 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
 		raw_spin_lock(&ctx->lock);
 		raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
 		if (context_equiv(ctx, next_ctx)) {
+			void *ctx_data;
 			/*
 			 * XXX do we need a memory barrier of sorts
 			 * wrt to rcu_dereference() of perf_event_ctxp
@@ -2347,6 +2348,11 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
 			next->perf_event_ctxp[ctxn] = ctx;
 			ctx->task = next;
 			next_ctx->task = task;
+
+			ctx_data = next_ctx->task_ctx_data;
+			next_ctx->task_ctx_data = ctx->task_ctx_data;
+			ctx->task_ctx_data = ctx_data;
+
 			do_switch = 0;
 
 			perf_event_sync_stat(ctx, next_ctx);
-- 
1.9.0

--
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/