1 files changed, 83 insertions, 8 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6ff07ad0ede3..c55f7e274613 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -314,6 +314,20 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
         if ((ops->flags & FL_GLOBAL_CONTROL_MASK) == FL_GLOBAL_CONTROL_MASK)
                 return -EINVAL;
 
+#ifndef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+        /*
+         * If the ftrace_ops specifies SAVE_REGS, then it only can be used
+         * if the arch supports it, or SAVE_REGS_IF_SUPPORTED is also set.
+         * Setting SAVE_REGS_IF_SUPPORTED makes SAVE_REGS irrelevant.
+         */
+        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS &&
+            !(ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED))
+                return -EINVAL;
+
+        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED)
+                ops->flags |= FTRACE_OPS_FL_SAVE_REGS;
+#endif
+
         if (!core_kernel_data((unsigned long)ops))
                 ops->flags |= FTRACE_OPS_FL_DYNAMIC;
 
@@ -1515,6 +1529,12 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
                         rec->flags++;
                         if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
                                 return;
+                        /*
+                         * If any ops wants regs saved for this function
+                         * then all ops will get saved regs.
+                         */
+                        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
+                                rec->flags |= FTRACE_FL_REGS;
                 } else {
                         if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
                                 return;
@@ -1606,18 +1626,59 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
         if (enable && (rec->flags & ~FTRACE_FL_MASK))
                 flag = FTRACE_FL_ENABLED;
 
+        /*
+         * If enabling and the REGS flag does not match the REGS_EN, then
+         * do not ignore this record. Set flags to fail the compare against
+         * ENABLED.
+         */
+        if (flag &&
+            (!(rec->flags & FTRACE_FL_REGS) != !(rec->flags & FTRACE_FL_REGS_EN)))
+                flag |= FTRACE_FL_REGS;
+
         /* If the state of this record hasn't changed, then do nothing */
         if ((rec->flags & FTRACE_FL_ENABLED) == flag)
                 return FTRACE_UPDATE_IGNORE;
 
         if (flag) {
-                if (update)
+                /* Save off if rec is being enabled (for return value) */
+                flag ^= rec->flags & FTRACE_FL_ENABLED;
+
+                if (update) {
                         rec->flags |= FTRACE_FL_ENABLED;
-                return FTRACE_UPDATE_MAKE_CALL;
+                        if (flag & FTRACE_FL_REGS) {
+                                if (rec->flags & FTRACE_FL_REGS)
+                                        rec->flags |= FTRACE_FL_REGS_EN;
+                                else
+                                        rec->flags &= ~FTRACE_FL_REGS_EN;
+                        }
+                }
+
+                /*
+                 * If this record is being updated from a nop, then
+                 *   return UPDATE_MAKE_CALL.
+                 * Otherwise, if the EN flag is set, then return
+                 *   UPDATE_MODIFY_CALL_REGS to tell the caller to convert
+                 *   from the non-save regs, to a save regs function.
+                 * Otherwise,
+                 *   return UPDATE_MODIFY_CALL to tell the caller to convert
+                 *   from the save regs, to a non-save regs function.
+                 */
+                if (flag & FTRACE_FL_ENABLED)
+                        return FTRACE_UPDATE_MAKE_CALL;
+                else if (rec->flags & FTRACE_FL_REGS_EN)
+                        return FTRACE_UPDATE_MODIFY_CALL_REGS;
+                else
+                        return FTRACE_UPDATE_MODIFY_CALL;
         }
 
-        if (update)
-                rec->flags &= ~FTRACE_FL_ENABLED;
+        if (update) {
+                /* If there's no more users, clear all flags */
+                if (!(rec->flags & ~FTRACE_FL_MASK))
+                        rec->flags = 0;
+                else
+                        /* Just disable the record (keep REGS state) */
+                        rec->flags &= ~FTRACE_FL_ENABLED;
+        }
 
         return FTRACE_UPDATE_MAKE_NOP;
 }
@@ -1652,13 +1713,17 @@ int ftrace_test_record(struct dyn_ftrace *rec, int enable)
 static int
 __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 {
+        unsigned long ftrace_old_addr;
         unsigned long ftrace_addr;
         int ret;
 
-        ftrace_addr = (unsigned long)FTRACE_ADDR;
-
         ret = ftrace_update_record(rec, enable);
 
+        if (rec->flags & FTRACE_FL_REGS)
+                ftrace_addr = (unsigned long)FTRACE_REGS_ADDR;
+        else
+                ftrace_addr = (unsigned long)FTRACE_ADDR;
+
         switch (ret) {
         case FTRACE_UPDATE_IGNORE:
                 return 0;
@@ -1668,6 +1733,15 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 
         case FTRACE_UPDATE_MAKE_NOP:
                 return ftrace_make_nop(NULL, rec, ftrace_addr);
+
+        case FTRACE_UPDATE_MODIFY_CALL_REGS:
+        case FTRACE_UPDATE_MODIFY_CALL:
+                if (rec->flags & FTRACE_FL_REGS)
+                        ftrace_old_addr = (unsigned long)FTRACE_ADDR;
+                else
+                        ftrace_old_addr = (unsigned long)FTRACE_REGS_ADDR;
+
+                return ftrace_modify_call(rec, ftrace_old_addr, ftrace_addr);
         }
 
         return -1; /* unknow ftrace bug */
@@ -2421,8 +2495,9 @@ static int t_show(struct seq_file *m, void *v)
 
         seq_printf(m, "%ps", (void *)rec->ip);
         if (iter->flags & FTRACE_ITER_ENABLED)
-                seq_printf(m, " (%ld)",
-                           rec->flags & ~FTRACE_FL_MASK);
+                seq_printf(m, " (%ld)%s",
+                           rec->flags & ~FTRACE_FL_MASK,
+                           rec->flags & FTRACE_FL_REGS ? " R" : "");
         seq_printf(m, "\n");
 
         return 0;