[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>
diff --git a/include/asm-sparc64/cacheflush.h b/include/asm-sparc64/cacheflush.h
index 86f0293..51b26e81 100644
--- a/include/asm-sparc64/cacheflush.h
+++ b/include/asm-sparc64/cacheflush.h
@@ -49,16 +49,22 @@
#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)