ftrace: return error on failed modified text.

Have the ftrace_modify_code return error values:

  -EFAULT on error of reading the address

  -EINVAL if what is read does not match what it expected

  -EPERM  if the write fails to update after a successful match.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 15 insertions, 6 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1f54a94189fe..b2de8de77356 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -596,22 +596,22 @@ ftrace_code_disable(struct dyn_ftrace *rec)
 {
         unsigned long ip;
         unsigned char *nop, *call;
-        int failed;
+        int ret;
 
         ip = rec->ip;
 
         nop = ftrace_nop_replace();
         call = ftrace_call_replace(ip, mcount_addr);
 
-        failed = ftrace_modify_code(ip, call, nop);
-        if (failed) {
-                switch (failed) {
-                case 1:
+        ret = ftrace_modify_code(ip, call, nop);
+        if (ret) {
+                switch (ret) {
+                case -EFAULT:
                         WARN_ON_ONCE(1);
                         pr_info("ftrace faulted on modifying ");
                         print_ip_sym(ip);
                         break;
-                case 2:
+                case -EINVAL:
                         WARN_ON_ONCE(1);
                         pr_info("ftrace failed to modify ");
                         print_ip_sym(ip);
@@ -620,6 +620,15 @@ ftrace_code_disable(struct dyn_ftrace *rec)
                         print_ip_ins(" replace: ", nop);
                         printk(KERN_CONT "\n");
                         break;
+                case -EPERM:
+                        WARN_ON_ONCE(1);
+                        pr_info("ftrace faulted on writing ");
+                        print_ip_sym(ip);
+                        break;
+                default:
+                        WARN_ON_ONCE(1);
+                        pr_info("ftrace faulted on unknown error ");
+                        print_ip_sym(ip);
                 }
 
                 rec->flags |= FTRACE_FL_FAILED;