parisc: Ensure full cache coherency for kmap/kunmap

Helge Deller noted a few weeks ago problems with the AIO support on
parisc. This change is the result of numerous iterations on how best to
deal with this problem.

The solution adopted here is to provide full cache coherency in a
uniform manner on all parisc systems. This involves calling
flush_dcache_page() on kmap operations and flush_kernel_dcache_page() on
kunmap operations. As a result, the copy_user_page() and
clear_user_page() functions can be removed and the overall code is
simpler.

The change ensures that both userspace and kernel aliases to a mapped
page are invalidated and flushed. This is necessary for the correct
operation of PA8800 and PA8900 based systems which do not support
inequivalent aliases.

With this change, I have observed no cache related issues on c8000 and
rp3440. It is now possible for example to do kernel builds with "-j64"
on four way systems.

On systems using XFS file systems, the patch recently posted by Mikulas
Patocka to "fix crash using XFS on loopback" is needed to avoid a hang
caused by an uninitialized lock passed to flush_dcache_page() in the
page struct.

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 f0e2784e7ccacd6c6d0856ce87d1f1d26e81c083..2f9b751878ba86bf6cc32cfdadd9b7847ad158d5 100644 (file)
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -125,42 +125,38 @@ flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vma
 void mark_rodata_ro(void);
 #endif
 
-#ifdef CONFIG_PA8X00
-/* Only pa8800, pa8900 needs this */
-
 #include <asm/kmap_types.h>
 
 #define ARCH_HAS_KMAP
 
-void kunmap_parisc(void *addr);
-
 static inline void *kmap(struct page *page)
 {
        might_sleep();
+       flush_dcache_page(page);
        return page_address(page);
 }
 
 static inline void kunmap(struct page *page)
 {
-       kunmap_parisc(page_address(page));
+       flush_kernel_dcache_page_addr(page_address(page));
 }
 
 static inline void *kmap_atomic(struct page *page)
 {
        pagefault_disable();
+       flush_dcache_page(page);
        return page_address(page);
 }
 
 static inline void __kunmap_atomic(void *addr)
 {
-       kunmap_parisc(addr);
+       flush_kernel_dcache_page_addr(addr);
        pagefault_enable();
 }
 
 #define kmap_atomic_prot(page, prot)   kmap_atomic(page)
 #define kmap_atomic_pfn(pfn)   kmap_atomic(pfn_to_page(pfn))
 #define kmap_atomic_to_page(ptr)       virt_to_page(ptr)
-#endif
 
 #endif /* _PARISC_CACHEFLUSH_H */
 

diff --git a/arch/parisc/include/asm/page.h b/arch/parisc/include/asm/page.h
index b7adb2ac049c0e6b72817dee3df92d124c612e42..c53fc63149e8312437fe4109e8070495ba39d90a 100644 (file)
--- a/arch/parisc/include/asm/page.h
+++ b/arch/parisc/include/asm/page.h
@@ -28,9 +28,8 @@ struct page;
 
 void clear_page_asm(void *page);
 void copy_page_asm(void *to, void *from);
-void clear_user_page(void *vto, unsigned long vaddr, struct page *pg);
-void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
-                          struct page *pg);
+#define clear_user_page(vto, vaddr, page) clear_page_asm(vto)
+#define copy_user_page(vto, vfrom, vaddr, page) copy_page_asm(vto, vfrom)
 
 /* #define CONFIG_PARISC_TMPALIAS */
 

diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index c035673209f732f0850aaa4dc98d2d49eee3b74c..a72545554a3154c254eace0648a769d4df645b25 100644 (file)
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -388,41 +388,6 @@ void flush_kernel_dcache_page_addr(void *addr)
 }
 EXPORT_SYMBOL(flush_kernel_dcache_page_addr);
 
-void clear_user_page(void *vto, unsigned long vaddr, struct page *page)
-{
-       clear_page_asm(vto);
-       if (!parisc_requires_coherency())
-               flush_kernel_dcache_page_asm(vto);
-}
-EXPORT_SYMBOL(clear_user_page);
-
-void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
-       struct page *pg)
-{
-       /* Copy using kernel mapping.  No coherency is needed
-          (all in kmap/kunmap) on machines that don't support
-          non-equivalent aliasing.  However, the `from' page
-          needs to be flushed 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);
-       if (!parisc_requires_coherency())
-               flush_kernel_dcache_page_asm(vto);
-}
-EXPORT_SYMBOL(copy_user_page);
-
-#ifdef CONFIG_PA8X00
-
-void kunmap_parisc(void *addr)
-{
-       if (parisc_requires_coherency())
-               flush_kernel_dcache_page_addr(addr);
-}
-EXPORT_SYMBOL(kunmap_parisc);
-#endif
-
 void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)
 {
        unsigned long flags;