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parisc: fix cache-flushing

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This commit:
f8dae00684: 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>
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2014-01-31 21:33:17 +01:00
parent 8a10bc9d27
commit 57737c49dd
3 changed files with 16 additions and 3 deletions
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2
arch/parisc/include/asm/cacheflush.h
View file

@ -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 *page)
static inline void *kmap_atomic(struct page *page)
{
pagefault_disable();
flush_dcache_page(page);
return page_address(page);
}

3
arch/parisc/include/asm/page.h
View file

@ -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 */

14
arch/parisc/kernel/cache.c
View file

@ -388,6 +388,20 @@ void flush_kernel_dcache_page_addr(void *addr)
}
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;