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authorSuresh Siddha <suresh.b.siddha@intel.com>2009-10-14 14:46:56 -0700
committerH. Peter Anvin <hpa@zytor.com>2009-10-20 14:46:00 +0900
commit74e081797bd9d2a7d8005fe519e719df343a2ba8 (patch)
treef210cca2002f87bf4cb17c20b853c129ce1df8f9 /arch/x86/mm/init_64.c
parentb9af7c0d44b8bb71e3af5e94688d076414aa8c87 (diff)
x86-64: align RODATA kernel section to 2MB with CONFIG_DEBUG_RODATA
CONFIG_DEBUG_RODATA chops the large pages spanning boundaries of kernel text/rodata/data to small 4KB pages as they are mapped with different attributes (text as RO, RODATA as RO and NX etc). On x86_64, preserve the large page mappings for kernel text/rodata/data boundaries when CONFIG_DEBUG_RODATA is enabled. This is done by allowing the RODATA section to be hugepage aligned and having same RWX attributes for the 2MB page boundaries Extra Memory pages padding the sections will be freed during the end of the boot and the kernel identity mappings will have different RWX permissions compared to the kernel text mappings. Kernel identity mappings to these physical pages will be mapped with smaller pages but large page mappings are still retained for kernel text,rodata,data mappings. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20091014220254.190119924@sbs-t61.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/mm/init_64.c')
-rw-r--r--arch/x86/mm/init_64.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 7dafd4159ad..0ed09fad6aa 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -727,9 +727,13 @@ void set_kernel_text_ro(void)
void mark_rodata_ro(void)
{
- unsigned long start = PFN_ALIGN(_text), end = PFN_ALIGN(__end_rodata);
+ unsigned long start = PFN_ALIGN(_text);
unsigned long rodata_start =
((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
+ unsigned long end = (unsigned long) &__end_rodata_hpage_align;
+ 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;
printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
(end - start) >> 10);
@@ -752,6 +756,14 @@ void mark_rodata_ro(void)
printk(KERN_INFO "Testing CPA: again\n");
set_memory_ro(start, (end-start) >> PAGE_SHIFT);
#endif
+
+ free_init_pages("unused kernel memory",
+ (unsigned long) page_address(virt_to_page(text_end)),
+ (unsigned long)
+ page_address(virt_to_page(rodata_start)));
+ free_init_pages("unused kernel memory",
+ (unsigned long) page_address(virt_to_page(rodata_end)),
+ (unsigned long) page_address(virt_to_page(data_start)));
}
#endif