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 ec30d10154b657a63ab07b5e25b4298c10f4aabe..f96eca21ad8fe4adb65f24856cab2a4b62af7c74 100644 (file)
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -710,6 +710,8 @@ void mark_rodata_ro(void)
        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 @@ void mark_rodata_ro(void)
        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 32ba13b0f818183bbeb2eb37eba74c1bdc4a35a9..41824e776b6ca7b0a0339bbbbd5e9f19ed9e4406 100644 (file)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -766,6 +766,13 @@ EXPORT_SYMBOL_GPL(rodata_test_data);
 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 @@ void mark_rodata_ro(void)
         * 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();