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authorMichael Ellerman <mpe@ellerman.id.au>2014-06-10 16:46:21 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-06-11 17:03:41 +1000
commit3df48c981d5a9610e02e9270b1bc4274fb536710 (patch)
tree24eff58c6d06a87f4413ab43c481d14c864d2b25 /arch
parentcaf69ba62768d3bae4fa8e6ad734cd5565207bd4 (diff)
powerpc/perf: Ensure all EBB register state is cleared on fork()
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@ellerman.id.au> Cc: stable@vger.kernel.org [v3.11+] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/include/asm/switch_to.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index d2468eb12639..58abeda64cb7 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -86,6 +86,8 @@ static inline void clear_task_ebb(struct task_struct *t)
{
#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;