5 files changed, 100 insertions, 54 deletions

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 9b6a1fa19e70..2bb43b433e07 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -17,6 +17,14 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
          */
         return addr - 1;
 }
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+struct dyn_arch_ftrace {
+        /* No extra data needed for x86 */
+};
+
+#endif /*  CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
 
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index fe832738e1e2..762222ad1387 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -166,7 +166,7 @@ static int ftrace_calc_offset(long ip, long addr)
         return (int)(addr - ip);
 }
 
-unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 {
         static union ftrace_code_union calc;
 
@@ -311,12 +311,12 @@ do_ftrace_mod_code(unsigned long ip, void *new_code)
 
 static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];
 
-unsigned char *ftrace_nop_replace(void)
+static unsigned char *ftrace_nop_replace(void)
 {
         return ftrace_nop;
 }
 
-int
+static int
 ftrace_modify_code(unsigned long ip, unsigned char *old_code,
                    unsigned char *new_code)
 {
@@ -349,6 +349,29 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
         return 0;
 }
 
+int ftrace_make_nop(struct module *mod,
+                    struct dyn_ftrace *rec, unsigned long addr)
+{
+        unsigned char *new, *old;
+        unsigned long ip = rec->ip;
+
+        old = ftrace_call_replace(ip, addr);
+        new = ftrace_nop_replace();
+
+        return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+        unsigned char *new, *old;
+        unsigned long ip = rec->ip;
+
+        old = ftrace_nop_replace();
+        new = ftrace_call_replace(ip, addr);
+
+        return ftrace_modify_code(rec->ip, old, new);
+}
+
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
         unsigned long ip = (unsigned long)(&ftrace_call);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 4fbc4a8b86a5..166a2070ef65 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -74,6 +74,9 @@ static inline void ftrace_start(void) { }
 #endif /* CONFIG_FUNCTION_TRACER */
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+/* asm/ftrace.h must be defined for archs supporting dynamic ftrace */
+#include <asm/ftrace.h>
+
 enum {
         FTRACE_FL_FREE          = (1 << 0),
         FTRACE_FL_FAILED        = (1 << 1),
@@ -88,6 +91,7 @@ struct dyn_ftrace {
         struct list_head        list;
         unsigned long           ip; /* address of mcount call-site */
         unsigned long           flags;
+        struct dyn_arch_ftrace  arch;
 };
 
 int ftrace_force_update(void);
@@ -95,22 +99,40 @@ void ftrace_set_filter(unsigned char *buf, int len, int reset);
 
 /* defined in arch */
 extern int ftrace_ip_converted(unsigned long ip);
-extern unsigned char *ftrace_nop_replace(void);
-extern unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr);
 extern int ftrace_dyn_arch_init(void *data);
 extern int ftrace_update_ftrace_func(ftrace_func_t func);
 extern void ftrace_caller(void);
 extern void ftrace_call(void);
 extern void mcount_call(void);
 
-/* May be defined in arch */
-extern int ftrace_arch_read_dyn_info(char *buf, int size);
+/**
+ * ftrace_make_nop - convert code into top
+ * @mod: module structure if called by module load initialization
+ * @rec: the mcount call site record
+ * @addr: the address that the call site should be calling
+ *
+ * This is a very sensitive operation and great care needs
+ * to be taken by the arch.  The operation should carefully
+ * read the location, check to see if what is read is indeed
+ * what we expect it to be, and then on success of the compare,
+ * it should write to the location.
+ *
+ * The code segment at @rec->ip should be a caller to @addr
+ *
+ * Return must be:
+ *  0 on success
+ *  -EFAULT on error reading the location
+ *  -EINVAL on a failed compare of the contents
+ *  -EPERM  on error writing to the location
+ * Any other value will be considered a failure.
+ */
+extern int ftrace_make_nop(struct module *mod,
+                           struct dyn_ftrace *rec, unsigned long addr);
 
 /**
- * ftrace_modify_code - modify code segment
- * @ip: the address of the code segment
- * @old_code: the contents of what is expected to be there
- * @new_code: the code to patch in
+ * ftrace_make_call - convert a nop call site into a call to addr
+ * @rec: the mcount call site record
+ * @addr: the address that the call site should call
  *
  * This is a very sensitive operation and great care needs
  * to be taken by the arch.  The operation should carefully
@@ -118,6 +140,8 @@ extern int ftrace_arch_read_dyn_info(char *buf, int size);
  * what we expect it to be, and then on success of the compare,
  * it should write to the location.
  *
+ * The code segment at @rec->ip should be a nop
+ *
  * Return must be:
  *  0 on success
  *  -EFAULT on error reading the location
@@ -125,8 +149,11 @@ extern int ftrace_arch_read_dyn_info(char *buf, int size);
  *  -EPERM  on error writing to the location
  * Any other value will be considered a failure.
  */
-extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
-                              unsigned char *new_code);
+extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
+
+
+/* May be defined in arch */
+extern int ftrace_arch_read_dyn_info(char *buf, int size);
 
 extern int skip_trace(unsigned long ip);
 
@@ -259,11 +286,13 @@ static inline void ftrace_dump(void) { }
 
 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 extern void ftrace_init(void);
-extern void ftrace_init_module(unsigned long *start, unsigned long *end);
+extern void ftrace_init_module(struct module *mod,
+                               unsigned long *start, unsigned long *end);
 #else
 static inline void ftrace_init(void) { }
 static inline void
-ftrace_init_module(unsigned long *start, unsigned long *end) { }
+ftrace_init_module(struct module *mod,
+                   unsigned long *start, unsigned long *end) { }
 #endif
 
 
diff --git a/kernel/module.c b/kernel/module.c
index 1f4cc00e0c20..69791274e899 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2201,7 +2201,7 @@ static noinline struct module *load_module(void __user *umod,
         /* sechdrs[0].sh_size is always zero */
         mseg = section_objs(hdr, sechdrs, secstrings, "__mcount_loc",
                             sizeof(*mseg), &num_mcount);
-        ftrace_init_module(mseg, mseg + num_mcount);
+        ftrace_init_module(mod, mseg, mseg + num_mcount);
 
         err = module_finalize(hdr, sechdrs, mod);
         if (err < 0)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3940c71ac2a2..e9a5fbfce08e 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -358,9 +358,7 @@ static void print_ip_ins(const char *fmt, unsigned char *p)
                 printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
 }
 
-static void ftrace_bug(int failed, unsigned long ip,
-                       unsigned char *expected,
-                       unsigned char *replace)
+static void ftrace_bug(int failed, unsigned long ip)
 {
         switch (failed) {
         case -EFAULT:
@@ -372,9 +370,7 @@ static void ftrace_bug(int failed, unsigned long ip,
                 FTRACE_WARN_ON_ONCE(1);
                 pr_info("ftrace failed to modify ");
                 print_ip_sym(ip);
-                print_ip_ins(" expected: ", expected);
                 print_ip_ins(" actual: ", (unsigned char *)ip);
-                print_ip_ins(" replace: ", replace);
                 printk(KERN_CONT "\n");
                 break;
         case -EPERM:
@@ -392,8 +388,7 @@ static void ftrace_bug(int failed, unsigned long ip,
 #define FTRACE_ADDR ((long)(ftrace_caller))
 
 static int
-__ftrace_replace_code(struct dyn_ftrace *rec,
-                      unsigned char *old, unsigned char *new, int enable)
+__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 {
         unsigned long ip, fl;
 
@@ -435,12 +430,10 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
                  * otherwise enable it!
                  */
                 if (fl & FTRACE_FL_ENABLED) {
-                        /* swap new and old */
-                        new = old;
-                        old = ftrace_call_replace(ip, FTRACE_ADDR);
+                        enable = 0;
                         rec->flags &= ~FTRACE_FL_ENABLED;
                 } else {
-                        new = ftrace_call_replace(ip, FTRACE_ADDR);
+                        enable = 1;
                         rec->flags |= FTRACE_FL_ENABLED;
                 }
         } else {
@@ -453,10 +446,7 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
                         fl = rec->flags & (FTRACE_FL_NOTRACE | FTRACE_FL_ENABLED);
                         if (fl == FTRACE_FL_NOTRACE)
                                 return 0;
-
-                        new = ftrace_call_replace(ip, FTRACE_ADDR);
-                } else
-                        old = ftrace_call_replace(ip, FTRACE_ADDR);
+                }
 
                 if (enable) {
                         if (rec->flags & FTRACE_FL_ENABLED)
@@ -469,21 +459,18 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
                 }
         }
 
-        return ftrace_modify_code(ip, old, new);
+        if (enable)
+                return ftrace_make_call(rec, FTRACE_ADDR);
+        else
+                return ftrace_make_nop(NULL, rec, FTRACE_ADDR);
 }
 
 static void ftrace_replace_code(int enable)
 {
         int i, failed;
-        unsigned char *new = NULL, *old = NULL;
         struct dyn_ftrace *rec;
         struct ftrace_page *pg;
 
-        if (enable)
-                old = ftrace_nop_replace();
-        else
-                new = ftrace_nop_replace();
-
         for (pg = ftrace_pages_start; pg; pg = pg->next) {
                 for (i = 0; i < pg->index; i++) {
                         rec = &pg->records[i];
@@ -504,34 +491,30 @@ static void ftrace_replace_code(int enable)
                                 unfreeze_record(rec);
                         }
 
-                        failed = __ftrace_replace_code(rec, old, new, enable);
+                        failed = __ftrace_replace_code(rec, enable);
                         if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
                                 rec->flags |= FTRACE_FL_FAILED;
                                 if ((system_state == SYSTEM_BOOTING) ||
                                     !core_kernel_text(rec->ip)) {
                                         ftrace_free_rec(rec);
                                 } else
-                                        ftrace_bug(failed, rec->ip, old, new);
+                                        ftrace_bug(failed, rec->ip);
                         }
                 }
         }
 }
 
 static int
-ftrace_code_disable(struct dyn_ftrace *rec)
+ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
 {
         unsigned long ip;
-        unsigned char *nop, *call;
         int ret;
 
         ip = rec->ip;
 
-        nop = ftrace_nop_replace();
-        call = ftrace_call_replace(ip, mcount_addr);
-
-        ret = ftrace_modify_code(ip, call, nop);
+        ret = ftrace_make_nop(mod, rec, mcount_addr);
         if (ret) {
-                ftrace_bug(ret, ip, call, nop);
+                ftrace_bug(ret, ip);
                 rec->flags |= FTRACE_FL_FAILED;
                 return 0;
         }
@@ -650,7 +633,7 @@ static cycle_t		ftrace_update_time;
 static unsigned long    ftrace_update_cnt;
 unsigned long           ftrace_update_tot_cnt;
 
-static int ftrace_update_code(void)
+static int ftrace_update_code(struct module *mod)
 {
         struct dyn_ftrace *p, *t;
         cycle_t start, stop;
@@ -667,7 +650,7 @@ static int ftrace_update_code(void)
                 list_del_init(&p->list);
 
                 /* convert record (i.e, patch mcount-call with NOP) */
-                if (ftrace_code_disable(p)) {
+                if (ftrace_code_disable(mod, p)) {
                         p->flags |= FTRACE_FL_CONVERTED;
                         ftrace_update_cnt++;
                 } else
@@ -1309,7 +1292,8 @@ static __init int ftrace_init_debugfs(void)
 
 fs_initcall(ftrace_init_debugfs);
 
-static int ftrace_convert_nops(unsigned long *start,
+static int ftrace_convert_nops(struct module *mod,
+                               unsigned long *start,
                                unsigned long *end)
 {
         unsigned long *p;
@@ -1325,18 +1309,19 @@ static int ftrace_convert_nops(unsigned long *start,
 
         /* disable interrupts to prevent kstop machine */
         local_irq_save(flags);
-        ftrace_update_code();
+        ftrace_update_code(mod);
         local_irq_restore(flags);
         mutex_unlock(&ftrace_start_lock);
 
         return 0;
 }
 
-void ftrace_init_module(unsigned long *start, unsigned long *end)
+void ftrace_init_module(struct module *mod,
+                        unsigned long *start, unsigned long *end)
 {
         if (ftrace_disabled || start == end)
                 return;
-        ftrace_convert_nops(start, end);
+        ftrace_convert_nops(mod, start, end);
 }
 
 extern unsigned long __start_mcount_loc[];
@@ -1366,7 +1351,8 @@ void __init ftrace_init(void)
 
         last_ftrace_enabled = ftrace_enabled = 1;
 
-        ret = ftrace_convert_nops(__start_mcount_loc,
+        ret = ftrace_convert_nops(NULL,
+                                  __start_mcount_loc,
                                   __stop_mcount_loc);
 
         return;