2 files changed, 75 insertions, 6 deletions

diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index b298f7a631e6..17efecc2bf03 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -7,7 +7,19 @@
 
 #ifndef __ASSEMBLY__
 extern void _mcount(void);
-#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+       /* reloction of mcount call site is the same as the address */
+       return addr;
+}
+
+struct dyn_arch_ftrace {
+        /* nothing yet */
+};
+#endif /*  CONFIG_DYNAMIC_FTRACE */
+#endif /* __ASSEMBLY__ */
 
 #endif
 
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index f4b006ed0ab1..24c023a5cae8 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -33,12 +33,12 @@ static unsigned int ftrace_calc_offset(long ip, long addr)
         return (int)(addr - ip);
 }
 
-unsigned char *ftrace_nop_replace(void)
+static unsigned char *ftrace_nop_replace(void)
 {
         return (char *)&ftrace_nop;
 }
 
-unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 {
         static unsigned int op;
 
@@ -68,7 +68,7 @@ unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 # define _ASM_PTR       " .long "
 #endif
 
-int
+static int
 ftrace_modify_code(unsigned long ip, unsigned char *old_code,
                    unsigned char *new_code)
 {
@@ -113,6 +113,62 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
         return faulted;
 }
 
+static int test_24bit_addr(unsigned long ip, unsigned long addr)
+{
+        long diff;
+
+        /*
+         * Can we get to addr from ip in 24 bits?
+         *  (26 really, since we mulitply by 4 for 4 byte alignment)
+         */
+        diff = addr - ip;
+
+        /*
+         * Return true if diff is less than 1 << 25
+         *  and greater than -1 << 26.
+         */
+        return (diff < (1 << 25)) && (diff > (-1 << 26));
+}
+
+int ftrace_make_nop(struct module *mod,
+                    struct dyn_ftrace *rec, unsigned long addr)
+{
+        unsigned char *old, *new;
+
+        /*
+         * If the calling address is more that 24 bits away,
+         * then we had to use a trampoline to make the call.
+         * Otherwise just update the call site.
+         */
+        if (test_24bit_addr(rec->ip, addr)) {
+                /* within range */
+                old = ftrace_call_replace(rec->ip, addr);
+                new = ftrace_nop_replace();
+                return ftrace_modify_code(rec->ip, old, new);
+        }
+
+        return 0;
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+        unsigned char *old, *new;
+
+        /*
+         * If the calling address is more that 24 bits away,
+         * then we had to use a trampoline to make the call.
+         * Otherwise just update the call site.
+         */
+        if (test_24bit_addr(rec->ip, addr)) {
+                /* within range */
+                old = ftrace_nop_replace();
+                new = ftrace_call_replace(rec->ip, addr);
+                return ftrace_modify_code(rec->ip, old, new);
+        }
+
+        return 0;
+}
+
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
         unsigned long ip = (unsigned long)(&ftrace_call);
@@ -128,9 +184,10 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
 int __init ftrace_dyn_arch_init(void *data)
 {
-        /* This is running in kstop_machine */
+        /* caller expects data to be zero */
+        unsigned long *p = data;
 
-        ftrace_mcount_set(data);
+        *p = 0;
 
         return 0;
 }