parisc: fix cache-flushing

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>
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index 2f9b751878ba86bf6cc32cfdadd9b7847ad158d5..de65f66ea64e7538f4f7c431ca3800e86c152e5d 100644 (file)
--- 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 *page)
 static inline void *kmap_atomic(struct page *page)
 {
        pagefault_disable();
-       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 c53fc63149e8312437fe4109e8070495ba39d90a..637fe031aa8476d743a8141ca9b549019985a0c6 100644 (file)
--- 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 */
 

diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index a72545554a3154c254eace0648a769d4df645b25..ac87a40502e6f6a0e11d21eaf6789259859ad092 100644 (file)
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -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;