[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/fixmap.h b/include/asm-mips/fixmap.h
index 6959bdb..02c8a13 100644
--- a/include/asm-mips/fixmap.h
+++ b/include/asm-mips/fixmap.h
@@ -45,8 +45,16 @@
* fix-mapped?
*/
enum fixed_addresses {
+#define FIX_N_COLOURS 8
+ FIX_CMAP_BEGIN,
+#ifdef CONFIG_MIPS_MT_SMTC
+ FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS),
+#else
+ FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
+#endif
#ifdef CONFIG_HIGHMEM
- FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
+ /* reserved pte's for temporary kernel mappings */
+ FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
#endif
__end_of_fixed_addresses
@@ -70,9 +78,9 @@
* at the top of mem..
*/
#if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
-#define FIXADDR_TOP (0xff000000UL - 0x2000)
+#define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000))
#else
-#define FIXADDR_TOP (0xffffe000UL)
+#define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000)
#endif
#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)