This is a note to let you know that I've just added the patch titled
powerpc/perf: Ensure all EBB register state is cleared on fork()
to the 3.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-perf-ensure-all-ebb-register-state-is-cleared-on-fork.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3df48c981d5a9610e02e9270b1bc4274fb536710 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Date: Tue, 10 Jun 2014 16:46:21 +1000
Subject: powerpc/perf: Ensure all EBB register state is cleared on fork()
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
commit 3df48c981d5a9610e02e9270b1bc4274fb536710 upstream.
In commit 330a1eb "Core EBB support for 64-bit book3s" I messed up
clear_task_ebb(). It clears some but not all of the task's Event Based
Branch (EBB) registers when we duplicate a task struct.
That allows a child task to observe the EBBHR & EBBRR of its parent,
which it should not be able to do.
Fix it by clearing EBBHR & EBBRR.
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/switch_to.h | 2 ++
1 file changed, 2 insertions(+)
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -84,6 +84,8 @@ static inline void clear_task_ebb(struct
{
#ifdef CONFIG_PPC_BOOK3S_64
/* EBB perf events are not inherited, so clear all EBB state. */
+ t->thread.ebbrr = 0;
+ t->thread.ebbhr = 0;
t->thread.bescr = 0;
t->thread.mmcr2 = 0;
t->thread.mmcr0 = 0;
Patches currently in stable-queue which might be from mpe@xxxxxxxxxxxxxx are
queue-3.15/powerpc-perf-ensure-all-ebb-register-state-is-cleared-on-fork.patch
queue-3.15/powerpc-mm-check-paca-psize-is-up-to-date-for-huge-mappings.patch
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