1 files changed, 69 insertions, 4 deletions

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index c3a7cb4bf6e6..1d414029f1d8 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -206,6 +206,21 @@ static int
 ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
                    unsigned const char *new_code);
 
+/*
+ * Should never be called:
+ *  As it is only called by __ftrace_replace_code() which is called by
+ *  ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
+ *  which is called to turn mcount into nops or nops into function calls
+ *  but not to convert a function from not using regs to one that uses
+ *  regs, which ftrace_modify_call() is for.
+ */
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+                                 unsigned long addr)
+{
+        WARN_ON(1);
+        return -EINVAL;
+}
+
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
         unsigned long ip = (unsigned long)(&ftrace_call);
@@ -220,6 +235,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
         ret = ftrace_modify_code(ip, old, new);
 
+        /* Also update the regs callback function */
+        if (!ret) {
+                ip = (unsigned long)(&ftrace_regs_call);
+                memcpy(old, &ftrace_regs_call, MCOUNT_INSN_SIZE);
+                new = ftrace_call_replace(ip, (unsigned long)func);
+                ret = ftrace_modify_code(ip, old, new);
+        }
+
         atomic_dec(&modifying_ftrace_code);
 
         return ret;
@@ -299,6 +322,32 @@ static int add_brk_on_nop(struct dyn_ftrace *rec)
         return add_break(rec->ip, old);
 }
 
+/*
+ * If the record has the FTRACE_FL_REGS set, that means that it
+ * wants to convert to a callback that saves all regs. If FTRACE_FL_REGS
+ * is not not set, then it wants to convert to the normal callback.
+ */
+static unsigned long get_ftrace_addr(struct dyn_ftrace *rec)
+{
+        if (rec->flags & FTRACE_FL_REGS)
+                return (unsigned long)FTRACE_REGS_ADDR;
+        else
+                return (unsigned long)FTRACE_ADDR;
+}
+
+/*
+ * The FTRACE_FL_REGS_EN is set when the record already points to
+ * a function that saves all the regs. Basically the '_EN' version
+ * represents the current state of the function.
+ */
+static unsigned long get_ftrace_old_addr(struct dyn_ftrace *rec)
+{
+        if (rec->flags & FTRACE_FL_REGS_EN)
+                return (unsigned long)FTRACE_REGS_ADDR;
+        else
+                return (unsigned long)FTRACE_ADDR;
+}
+
 static int add_breakpoints(struct dyn_ftrace *rec, int enable)
 {
         unsigned long ftrace_addr;
@@ -306,7 +355,7 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
 
         ret = ftrace_test_record(rec, enable);
 
-        ftrace_addr = (unsigned long)FTRACE_ADDR;
+        ftrace_addr = get_ftrace_addr(rec);
 
         switch (ret) {
         case FTRACE_UPDATE_IGNORE:
@@ -316,6 +365,10 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
                 /* converting nop to call */
                 return add_brk_on_nop(rec);
 
+        case FTRACE_UPDATE_MODIFY_CALL_REGS:
+        case FTRACE_UPDATE_MODIFY_CALL:
+                ftrace_addr = get_ftrace_old_addr(rec);
+                /* fall through */
         case FTRACE_UPDATE_MAKE_NOP:
                 /* converting a call to a nop */
                 return add_brk_on_call(rec, ftrace_addr);
@@ -360,13 +413,21 @@ static int remove_breakpoint(struct dyn_ftrace *rec)
                  * If not, don't touch the breakpoint, we make just create
                  * a disaster.
                  */
-                ftrace_addr = (unsigned long)FTRACE_ADDR;
+                ftrace_addr = get_ftrace_addr(rec);
+                nop = ftrace_call_replace(ip, ftrace_addr);
+
+                if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
+                        goto update;
+
+                /* Check both ftrace_addr and ftrace_old_addr */
+                ftrace_addr = get_ftrace_old_addr(rec);
                 nop = ftrace_call_replace(ip, ftrace_addr);
 
                 if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
                         return -EINVAL;
         }
 
+ update:
         return probe_kernel_write((void *)ip, &nop[0], 1);
 }
 
@@ -405,12 +466,14 @@ static int add_update(struct dyn_ftrace *rec, int enable)
 
         ret = ftrace_test_record(rec, enable);
 
-        ftrace_addr = (unsigned long)FTRACE_ADDR;
+        ftrace_addr  = get_ftrace_addr(rec);
 
         switch (ret) {
         case FTRACE_UPDATE_IGNORE:
                 return 0;
 
+        case FTRACE_UPDATE_MODIFY_CALL_REGS:
+        case FTRACE_UPDATE_MODIFY_CALL:
         case FTRACE_UPDATE_MAKE_CALL:
                 /* converting nop to call */
                 return add_update_call(rec, ftrace_addr);
@@ -455,12 +518,14 @@ static int finish_update(struct dyn_ftrace *rec, int enable)
 
         ret = ftrace_update_record(rec, enable);
 
-        ftrace_addr = (unsigned long)FTRACE_ADDR;
+        ftrace_addr = get_ftrace_addr(rec);
 
         switch (ret) {
         case FTRACE_UPDATE_IGNORE:
                 return 0;
 
+        case FTRACE_UPDATE_MODIFY_CALL_REGS:
+        case FTRACE_UPDATE_MODIFY_CALL:
         case FTRACE_UPDATE_MAKE_CALL:
                 /* converting nop to call */
                 return finish_update_call(rec, ftrace_addr);