x86, cpa: Fix kernel text RO checks in static_protection()

Steven Rostedt reported that we are unconditionally making the
kernel text mapping as read-only. i.e., if someone does cpa() to
the kernel text area for setting/clearing any page table
attribute, we unconditionally clear the read-write attribute for
the kernel text mapping that is set at compile time.

We should delay (to forbid the write attribute) and enforce only
after the kernel has mapped the text as read-only.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20091029024820.996634347@sbs-t61.sc.intel.com>
[ marked kernel_set_to_readonly as __read_mostly ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index b54f6afe7ec4..eebb2cd2b9bf 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -176,6 +176,7 @@ void clflush_cache_range(void *addr, unsigned int size);
 #ifdef CONFIG_DEBUG_RODATA
 void mark_rodata_ro(void);
 extern const int rodata_test_data;
+extern int kernel_set_to_readonly;
 void set_kernel_text_rw(void);
 void set_kernel_text_ro(void);
 #else