[PATCH 3.13 125/140] parisc: fix cache-flushing

Greg Kroah-Hartman
2014-02-04T21:24:47Z

From: Helge Deller <deller@gmx.de>

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@gmx.de>
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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(-)

--- 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)
{
might_sleep();
- flush_dcache_page(page);
return page_address(page);
}

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

--- 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);

/* #define CONFIG_PARISC_TMPALIAS */

--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -388,6 +388,20 @@ void flush_kernel_dcache_page_addr(void
}
EXPORT_SYMBOL(flush_kernel_dcache_page_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);
+}
+EXPORT_SYMBOL(copy_user_page);
+
void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)
{
unsigned long flags;