1 files changed, 14 insertions, 14 deletions

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index c0062ad1e847..6fd7c4a1e532 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -121,15 +121,17 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
 }
 
 static int ftrace_modify_code(unsigned long pc, unsigned long old,
-                              unsigned long new)
+                              unsigned long new, bool validate)
 {
         unsigned long replaced;
 
-        if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
-                return -EFAULT;
+        if (validate) {
+                if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
+                        return -EFAULT;
 
-        if (replaced != old)
-                return -EINVAL;
+                if (replaced != old)
+                        return -EINVAL;
+        }
 
         if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
                 return -EPERM;
@@ -141,23 +143,21 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
 
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
-        unsigned long pc, old;
+        unsigned long pc;
         unsigned long new;
         int ret;
 
         pc = (unsigned long)&ftrace_call;
-        memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
         new = ftrace_call_replace(pc, (unsigned long)func);
 
-        ret = ftrace_modify_code(pc, old, new);
+        ret = ftrace_modify_code(pc, 0, new, false);
 
 #ifdef CONFIG_OLD_MCOUNT
         if (!ret) {
                 pc = (unsigned long)&ftrace_call_old;
-                memcpy(&old, &ftrace_call_old, MCOUNT_INSN_SIZE);
                 new = ftrace_call_replace(pc, (unsigned long)func);
 
-                ret = ftrace_modify_code(pc, old, new);
+                ret = ftrace_modify_code(pc, 0, new, false);
         }
 #endif
 
@@ -172,7 +172,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
         old = ftrace_nop_replace(rec);
         new = ftrace_call_replace(ip, adjust_address(rec, addr));
 
-        return ftrace_modify_code(rec->ip, old, new);
+        return ftrace_modify_code(rec->ip, old, new, true);
 }
 
 int ftrace_make_nop(struct module *mod,
@@ -185,7 +185,7 @@ int ftrace_make_nop(struct module *mod,
 
         old = ftrace_call_replace(ip, adjust_address(rec, addr));
         new = ftrace_nop_replace(rec);
-        ret = ftrace_modify_code(ip, old, new);
+        ret = ftrace_modify_code(ip, old, new, true);
 
 #ifdef CONFIG_OLD_MCOUNT
         if (ret == -EINVAL && addr == MCOUNT_ADDR) {
@@ -193,7 +193,7 @@ int ftrace_make_nop(struct module *mod,
 
                 old = ftrace_call_replace(ip, adjust_address(rec, addr));
                 new = ftrace_nop_replace(rec);
-                ret = ftrace_modify_code(ip, old, new);
+                ret = ftrace_modify_code(ip, old, new, true);
         }
 #endif
 
@@ -254,7 +254,7 @@ static int __ftrace_modify_caller(unsigned long *callsite,
         unsigned long old = enable ? nop : branch;
         unsigned long new = enable ? branch : nop;
 
-        return ftrace_modify_code(pc, old, new);
+        return ftrace_modify_code(pc, old, new, true);
 }
 
 static int ftrace_modify_graph_caller(bool enable)