From 72c4e18ba918be15833be996665eadfff4124f86 Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@c-s.fr>
Date: Wed, 19 Apr 2017 14:56:24 +0200
Subject: [PATCH 06/45] powerpc/mm: Only call store_updates_sp() on stores in
do_page_fault()
References: FATE#322447, bsc#1078248
Patch-mainline: v4.13-rc1
Git-commit: e8de85ca32f572f5dee00733022d8a1ce87aed3d
Function store_updates_sp() checks whether the faulting
instruction is a store updating r1. Therefore we can limit its calls
to store exceptions.
This patch is an improvement of commit a7a9dcd882a67 ("powerpc: Avoid
taking a data miss on every userspace instruction miss")
With the same microbenchmark app, run with 500 as argument, on an
MPC885 we get:
Before this patch: 152000 DTLB misses
After this patch: 147000 DTLB misses
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/mm/fault.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 0727b7ce727f..57847537655b 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -272,7 +272,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
* can result in fault, which will cause a deadlock when called with
* mmap_sem held
*/
- if (!is_exec && user_mode(regs))
+ if (is_write && user_mode(regs))
store_update_sp = store_updates_sp(regs);
if (user_mode(regs))
--
2.13.6