[PATCH] sparc64: Reduce ptrace cache flushing

We were flushing the D-cache excessively for ptrace() processing
and this makes debugging threads so slow as to be totally unusable.

All process page accesses via ptrace() go via access_process_vm().
This routine, for each process page, uses get_user_pages().  That
in turn does a flush_dcache_page() on the child pages before we
copy in/out the ptrace request data.

Therefore, all we need to do after the data movement is:

1) Flush the D-cache pages if the kernel maps the page to a different
   color than userspace does.
2) If we wrote to the page, we need to flush the I-cache on older cpus.

Previously we just flushed the entire cache at the end of a ptrace()
request, and that was beyond stupid.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 14 insertions, 8 deletions

diff --git a/include/asm-sparc64/cacheflush.h b/include/asm-sparc64/cacheflush.h
index 86f02937ff1b..51b26e81d828 100644
--- a/include/asm-sparc64/cacheflush.h
+++ b/include/asm-sparc64/cacheflush.h
@@ -49,16 +49,22 @@ extern void flush_dcache_page(struct page *page);
 #define flush_icache_page(vma, pg)      do { } while(0)
 #define flush_icache_user_range(vma,pg,adr,len) do { } while (0)
 
-#define copy_to_user_page(vma, page, vaddr, dst, src, len) \
-        do {                                                    \
-                flush_cache_page(vma, vaddr, page_to_pfn(page));\
-                memcpy(dst, src, len);                          \
+extern void flush_ptrace_access(struct vm_area_struct *, struct page *,
+                                unsigned long uaddr, void *kaddr,
+                                unsigned long len, int write);
+
+#define copy_to_user_page(vma, page, vaddr, dst, src, len)              \
+        do {                                                            \
+                flush_cache_page(vma, vaddr, page_to_pfn(page));        \
+                memcpy(dst, src, len);                                  \
+                flush_ptrace_access(vma, page, vaddr, src, len, 0);     \
         } while (0)
 
-#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
-        do {                                                    \
-                flush_cache_page(vma, vaddr, page_to_pfn(page));\
-                memcpy(dst, src, len);                          \
+#define copy_from_user_page(vma, page, vaddr, dst, src, len)            \
+        do {                                                            \
+                flush_cache_page(vma, vaddr, page_to_pfn(page));        \
+                memcpy(dst, src, len);                                  \
+                flush_ptrace_access(vma, page, vaddr, dst, len, 1);     \
         } while (0)
 
 #define flush_dcache_mmap_lock(mapping)         do { } while (0)