diff options
authorJohn David Anglin <dave.anglin@bell.net>2013-02-03 22:59:09 +0000
committerHelge Deller <deller@gmx.de>2013-02-20 22:49:19 +0100
commit7633453978c54874849c5f40487ac9e14d43fc12 (patch)
parent93c3e913e104c9277e32a0d7e03f268d146c57ee (diff)
parisc: fixes and cleanups in page cache flushing (1/4)
This is the first patch in a series of 4, with which the page cache flushing of parisc will gets fixed and enhanced. This even fixes the nasty "minifail" bug (http://wiki.parisc-linux.org/TestCases?highlight=%28minifail%29) which prevented parisc to stay an official debian port. Basically the flush in copy_user_page together with the TLB patch from commit 7139bc1579901b53db7e898789e916ee2fb52d78 is what fixes the minifail bug. This patch still uses the TMPALIAS approach. The new copy_user_page implementation calls flush_dcache_page_asm to flush the user dcache page (crucial for minifail fix) via a kernel TMPALIAS mapping. After that, it just copies the page using the kernel mapping. It does a final flush if needed. Generally it is hard to avoid doing some cache flushes using the kernel mapping (e.g., copy_to_user_page and copy_from_user_page). This patch depends on a subsequent change to pacache.S implementing clear_page_asm and copy_page_asm. These are optimized routines to clear and copy a page. The calls in clear_user_page and copy_user_page could be replaced by calls to memset and memcpy, respectively. I tested prefetch optimizations in clear_page_asm and copy_page_asm but didn't see any significant performance improvement on rp3440. I'm not sure if these are routines are significantly faster than memset and/or memcpy, but they are there for further performance evaluation. Signed-off-by: John David Anglin <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de>
3 files changed, 40 insertions, 34 deletions
diff --git a/arch/parisc/include/asm/page.h b/arch/parisc/include/asm/page.h
index 4e0e7dbf0f3..b7adb2ac049 100644
--- a/arch/parisc/include/asm/page.h
+++ b/arch/parisc/include/asm/page.h
@@ -21,15 +21,27 @@
#include <asm/types.h>
#include <asm/cache.h>
-#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
-#define copy_page(to,from) copy_user_page_asm((void *)(to), (void *)(from))
+#define clear_page(page) clear_page_asm((void *)(page))
+#define copy_page(to, from) copy_page_asm((void *)(to), (void *)(from))
struct page;
-void copy_user_page_asm(void *to, void *from);
+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);
-void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
+void clear_user_highpage(struct page *page, unsigned long vaddr);
+#define clear_user_highpage clear_user_highpage
+struct vm_area_struct;
+void copy_user_highpage(struct page *to, struct page *from,
+ unsigned long vaddr, struct vm_area_struct *vma);
* These are used to make use of C type-checking..
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index b89a85ab945..d9cbb4b22c9 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -329,17 +329,6 @@ EXPORT_SYMBOL(flush_kernel_dcache_page_asm);
-void clear_user_page_asm(void *page, unsigned long vaddr)
- unsigned long flags;
- /* This function is implemented in assembly in pacache.S */
- extern void __clear_user_page_asm(void *page, unsigned long vaddr);
- purge_tlb_start(flags);
- __clear_user_page_asm(page, vaddr);
- purge_tlb_end(flags);
#define FLUSH_THRESHOLD 0x80000 /* 0.5MB */
int parisc_cache_flush_threshold __read_mostly = FLUSH_THRESHOLD;
@@ -373,20 +362,9 @@ void __init parisc_setup_cache_timing(void)
printk(KERN_INFO "Setting cache flush threshold to %x (%d CPUs online)\n", parisc_cache_flush_threshold, num_online_cpus());
-extern void purge_kernel_dcache_page(unsigned long);
-extern void clear_user_page_asm(void *page, unsigned long vaddr);
-void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
- unsigned long flags;
- purge_kernel_dcache_page((unsigned long)page);
- purge_tlb_start(flags);
- pdtlb_kernel(page);
- purge_tlb_end(flags);
- clear_user_page_asm(page, vaddr);
+extern void purge_kernel_dcache_page_asm(unsigned long);
+extern void clear_user_page_asm(void *, unsigned long);
+extern void copy_user_page_asm(void *, void *, unsigned long);
void flush_kernel_dcache_page_addr(void *addr)
@@ -399,11 +377,26 @@ void flush_kernel_dcache_page_addr(void *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);
void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
- struct page *pg)
+ struct page *pg)
- /* no coherency needed (all in kmap/kunmap) */
- copy_user_page_asm(vto, vfrom);
+ /* 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())
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c
index ceec85de629..6795dc6c995 100644
--- a/arch/parisc/kernel/parisc_ksyms.c
+++ b/arch/parisc/kernel/parisc_ksyms.c
@@ -157,5 +157,6 @@ extern void _mcount(void);
-/* from pacache.S -- needed for copy_page */
+/* from pacache.S -- needed for clear/copy_page */