Merge git://git.infradead.org/ubifs-2.6

[cascardo/linux.git] / arch / x86 / kernel / ftrace.c

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 5a1b975..3096892 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -189,9 +189,26 @@ static void wait_for_nmi(void)
        nmi_wait_count++;
 }
 
+static inline int
+within(unsigned long addr, unsigned long start, unsigned long end)
+{
+       return addr >= start && addr < end;
+}
+
 static int
 do_ftrace_mod_code(unsigned long ip, void *new_code)
 {
+       /*
+        * On x86_64, kernel text mappings are mapped read-only with
+        * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
+        * of the kernel text mapping to modify the kernel text.
+        *
+        * For 32bit kernels, these mappings are same and we can use
+        * kernel identity mapping to modify code.
+        */
+       if (within(ip, (unsigned long)_text, (unsigned long)_etext))
+               ip = (unsigned long)__va(__pa(ip));
+
        mod_code_ip = (void *)ip;
        mod_code_newcode = new_code;