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authorSuresh Siddha <suresh.b.siddha@intel.com>2009-10-29 05:46:57 +0300
committerIngo Molnar <mingo@elte.hu>2009-11-02 19:16:36 +0300
commit55ca3cc1746335bb6ef1d3894ddb6d0c729b3518 (patch)
tree1678b567a1d4ebb92c51abc0234334023879c749 /arch/x86/kernel
parent502f660466ba7a66711ffdf414b1f7f1131dcbf7 (diff)
downloadlinux-55ca3cc1746335bb6ef1d3894ddb6d0c729b3518.tar.xz
x86_64, ftrace: Make ftrace use kernel identity mapping to modify code
On x86_64, kernel text mappings are mapped read-only with CONFIG_DEBUG_RODATA. So use the kernel identity mapping instead of the kernel text mapping to modify the kernel text. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <20091029024821.080941108@sbs-t61.sc.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/ftrace.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 9dbb527e1652..944e9820b4b5 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -187,9 +187,26 @@ 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;