powerpc: Don't write protect kernel text with CONFIG_DYNAMIC_FTRACE enabled
Stefan Roese [Thu, 14 Apr 2011 23:49:53 +0000 (23:49 +0000)]
This problem was noticed on an MPC855T platform. Ftrace did oops
when trying to write to the kernel text segment.

Many thanks to Joakim for finding the root cause of this problem.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/pte-common.h

index 811f04a..8d1569c 100644 (file)
@@ -162,7 +162,7 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
  * on platforms where such control is possible.
  */
 #if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\
-       defined(CONFIG_KPROBES)
+       defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE)
 #define PAGE_KERNEL_TEXT       PAGE_KERNEL_X
 #else
 #define PAGE_KERNEL_TEXT       PAGE_KERNEL_ROX