[PATCH 3.11 200/233] parisc: fix cache-flushing

From: Luis Henriques
Date: Fri Feb 07 2014 - 07:03:00 EST -stable review patch. If anyone has any objections, please let me know.


From: Helge Deller <deller@xxxxxx>

commit 57737c49dd72c96cfbcd4f66559f3ffc399aeb4f upstream.

This commit:
f8dae00684d678afa13041ef170cecfd1297ed40: parisc: Ensure full cache coherency for kmap/kunmap
caused negative caching side-effects, e.g. hanging processes with expect and
too many inequivalent alias messages from flush_dcache_page() on Debian 5 systems.

This patch now partly reverts it and has been in production use on our debian buildd
makeservers since a week without any major problems.

Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
arch/parisc/include/asm/cacheflush.h | 2 --
arch/parisc/include/asm/page.h | 3 ++-
arch/parisc/kernel/cache.c | 14 ++++++++++++++
3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index 2f9b751..de65f66 100644
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -132,7 +132,6 @@ void mark_rodata_ro(void);
static inline void *kmap(struct page *page)
- flush_dcache_page(page);
return page_address(page);

@@ -144,7 +143,6 @@ static inline void kunmap(struct page *page)
static inline void *kmap_atomic(struct page *page)
- flush_dcache_page(page);
return page_address(page);

diff --git a/arch/parisc/include/asm/page.h b/arch/parisc/include/asm/page.h
index c53fc63..637fe03 100644
--- a/arch/parisc/include/asm/page.h
+++ b/arch/parisc/include/asm/page.h
@@ -29,7 +29,8 @@ struct page;
void clear_page_asm(void *page);
void copy_page_asm(void *to, void *from);
#define clear_user_page(vto, vaddr, page) clear_page_asm(vto)
-#define copy_user_page(vto, vfrom, vaddr, page) copy_page_asm(vto, vfrom)
+void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
+ struct page *pg);


diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index a725455..ac87a40 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -388,6 +388,20 @@ void flush_kernel_dcache_page_addr(void *addr)

+void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
+ struct page *pg)
+ /* Copy using kernel mapping. No coherency is needed (all in
+ kunmap) for the `to' page. However, the `from' page needs to
+ be flushed through a mapping equivalent to the user mapping
+ before it can be accessed through the kernel mapping. */
+ preempt_disable();
+ flush_dcache_page_asm(__pa(vfrom), vaddr);
+ preempt_enable();
+ copy_page_asm(vto, vfrom);
void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)
unsigned long flags;

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