[PATCH 3.2 136/152] Revert "x86, mm: Set NX across entire PMD at boot"

From: Ben Hutchings
Date: Mon Feb 16 2015 - 21:46:51 EST

3.2.67-rc1 review patch. If anyone has any objections, please let me know.


From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>

This reverts commit a5c187d92d2ce30315f333b9dff33af832e8b443 which
was commit 45e2a9d4701d8c624d4a4bcdd1084eae31e92f58 upstream.

The previous commit caused suspend/resume to stop working on at least
some systems - specifically, the system would reboot when woken.

Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -778,7 +778,7 @@ void mark_rodata_ro(void)
unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
unsigned long data_start = (unsigned long) &_sdata;
- unsigned long all_end;
+ unsigned long all_end = PFN_ALIGN(&_end);

printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
(end - start) >> 10);
@@ -789,16 +789,7 @@ void mark_rodata_ro(void)
* The rodata/data/bss/brk section (but not the kernel text!)
* should also be not-executable.
- *
- * We align all_end to PMD_SIZE because the existing mapping
- * is a full PMD. If we would align _brk_end to PAGE_SIZE we
- * split the PMD and the reminder between _brk_end and the end
- * of the PMD will remain mapped executable.
- *
- * Any PMD which was setup after the one which covers _brk_end
- * has been zapped already via cleanup_highmem().
- all_end = roundup((unsigned long)_brk_end, PMD_SIZE);
set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);


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