[MIPS] Fix aliasing bug in copy_to_user_page / copy_from_user_page
The current implementation uses a sequence of a cacheflush and a copy.
This is racy in case of a multithreaded debuggee and renders GDB
virtually unusable.
Aside this fixes a performance hog rendering access to /proc/cmdline very
slow and resulting in a enough cache stalls for the 34K AP/SP programming
model to make the bare metal code on the non-Linux VPE miss RT deadlines.
The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/include/asm-mips/cacheflush.h b/include/asm-mips/cacheflush.h
index 9ab59e2..e3c9925 100644
--- a/include/asm-mips/cacheflush.h
+++ b/include/asm-mips/cacheflush.h
@@ -55,24 +55,13 @@
#define flush_cache_vmap(start, end) flush_cache_all()
#define flush_cache_vunmap(start, end) flush_cache_all()
-static inline void copy_to_user_page(struct vm_area_struct *vma,
+extern void copy_to_user_page(struct vm_area_struct *vma,
struct page *page, unsigned long vaddr, void *dst, const void *src,
- unsigned long len)
-{
- if (cpu_has_dc_aliases)
- flush_cache_page(vma, vaddr, page_to_pfn(page));
- memcpy(dst, src, len);
- __flush_icache_page(vma, page);
-}
+ unsigned long len);
-static inline void copy_from_user_page(struct vm_area_struct *vma,
+extern void copy_from_user_page(struct vm_area_struct *vma,
struct page *page, unsigned long vaddr, void *dst, const void *src,
- unsigned long len)
-{
- if (cpu_has_dc_aliases)
- flush_cache_page(vma, vaddr, page_to_pfn(page));
- memcpy(dst, src, len);
-}
+ unsigned long len);
extern void (*flush_cache_sigtramp)(unsigned long addr);
extern void (*flush_icache_all)(void);