ftrace: dont write protect kernel text
Dynamic ftrace cant work when the kernel has its text write protected.
This patch keeps the kernel from being write protected when
dynamic ftrace is in place.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index ec30d10..f96eca2 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -710,6 +710,8 @@
unsigned long start = PFN_ALIGN(_text);
unsigned long size = PFN_ALIGN(_etext) - start;
+#ifndef CONFIG_DYNAMIC_FTRACE
+ /* Dynamic tracing modifies the kernel text section */
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
printk(KERN_INFO "Write protecting the kernel text: %luk\n",
size >> 10);
@@ -722,6 +724,8 @@
printk(KERN_INFO "Testing CPA: write protecting again\n");
set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
#endif
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
start += size;
size = (unsigned long)__end_rodata - start;
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 32ba13b..41824e7 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -766,6 +766,13 @@
void mark_rodata_ro(void)
{
unsigned long start = PFN_ALIGN(_stext), end = PFN_ALIGN(__end_rodata);
+ unsigned long rodata_start =
+ ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+ /* Dynamic tracing modifies the kernel text section */
+ start = rodata_start;
+#endif
printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
(end - start) >> 10);
@@ -775,8 +782,7 @@
* The rodata section (but not the kernel text!) should also be
* not-executable.
*/
- start = ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
- set_memory_nx(start, (end - start) >> PAGE_SHIFT);
+ set_memory_nx(rodata_start, (end - start) >> PAGE_SHIFT);
rodata_test();