ftrace: use dynamic patching for updating mcount calls

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / x86 / kernel / ftrace.c

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index b69795efa2264008a7d168b564e2e9d173606d2d..9f44623e0072fbaa66af77b5f5c184477b6148ee 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -109,10 +109,49 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
        return faulted;
 }
 
-int __init ftrace_dyn_arch_init(void)
+notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+       unsigned long ip = (unsigned long)(&ftrace_call);
+       unsigned char old[5], *new;
+       int ret;
+
+       ip += CALL_BACK;
+
+       memcpy(old, &ftrace_call, 5);
+       new = ftrace_call_replace(ip, (unsigned long)func);
+       ret = ftrace_modify_code(ip, old, new);
+
+       return ret;
+}
+
+notrace int ftrace_mcount_set(unsigned long *data)
+{
+       unsigned long ip = (long)(&mcount_call);
+       unsigned long *addr = data;
+       unsigned char old[5], *new;
+
+       /* ip is at the location, but modify code will subtact this */
+       ip += CALL_BACK;
+
+       /*
+        * Replace the mcount stub with a pointer to the
+        * ip recorder function.
+        */
+       memcpy(old, &mcount_call, 5);
+       new = ftrace_call_replace(ip, *addr);
+       *addr = ftrace_modify_code(ip, old, new);
+
+       return 0;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
 {
        const unsigned char *const *noptable = find_nop_table();
 
+       /* This is running in kstop_machine */
+
+       ftrace_mcount_set(data);
+
        ftrace_nop = (unsigned long *)noptable[CALL_BACK];
 
        return 0;