Blackfin: add support for dynamic ftrace

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 77 insertions, 8 deletions

diff --git a/arch/blackfin/kernel/ftrace-entry.S b/arch/blackfin/kernel/ftrace-entry.S
index d66446b572c0..7eed00bbd26d 100644
--- a/arch/blackfin/kernel/ftrace-entry.S
+++ b/arch/blackfin/kernel/ftrace-entry.S
@@ -10,6 +10,18 @@
 
 .text
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+/* Simple stub so we can boot the kernel until runtime patching has
+ * disabled all calls to this.  Then it'll be unused.
+ */
+ENTRY(__mcount)
+# if ANOMALY_05000371
+        nop; nop; nop; nop;
+# endif
+        rts;
+ENDPROC(__mcount)
+
 /* GCC will have called us before setting up the function prologue, so we
  * can clobber the normal scratch registers, but we need to make sure to
  * save/restore the registers used for argument passing (R0-R2) in case
@@ -20,15 +32,65 @@
  * function.  And since GCC pushed the previous RETS for us, the previous
  * function will be waiting there.  mmmm pie.
  */
+ENTRY(_ftrace_caller)
+# ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
+        /* optional micro optimization: return if stopped */
+        p1.l = _function_trace_stop;
+        p1.h = _function_trace_stop;
+        r3 = [p1];
+        cc = r3 == 0;
+        if ! cc jump _ftrace_stub (bp);
+# endif
+
+        /* save first/second/third function arg and the return register */
+        [--sp] = r2;
+        [--sp] = r0;
+        [--sp] = r1;
+        [--sp] = rets;
+
+        /* function_trace_call(unsigned long ip, unsigned long parent_ip):
+         *  ip: this point was called by ...
+         *  parent_ip: ... this function
+         * the ip itself will need adjusting for the mcount call
+         */
+        r0 = rets;
+        r1 = [sp + 16]; /* skip the 4 local regs on stack */
+        r0 += -MCOUNT_INSN_SIZE;
+
+.globl _ftrace_call
+_ftrace_call:
+        call _ftrace_stub
+
+# ifdef CONFIG_FUNCTION_GRAPH_TRACER
+.globl _ftrace_graph_call
+_ftrace_graph_call:
+        nop;    /* jump _ftrace_graph_caller; */
+# endif
+
+        /* restore state and get out of dodge */
+.Lfinish_trace:
+        rets = [sp++];
+        r1 = [sp++];
+        r0 = [sp++];
+        r2 = [sp++];
+
+.globl _ftrace_stub
+_ftrace_stub:
+        rts;
+ENDPROC(_ftrace_caller)
+
+#else
+
+/* See documentation for _ftrace_caller */
 ENTRY(__mcount)
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
+# ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
         /* optional micro optimization: return if stopped */
         p1.l = _function_trace_stop;
         p1.h = _function_trace_stop;
         r3 = [p1];
         cc = r3 == 0;
         if ! cc jump _ftrace_stub (bp);
-#endif
+# endif
 
         /* save third function arg early so we can do testing below */
         [--sp] = r2;
@@ -44,7 +106,7 @@ ENTRY(__mcount)
         cc = r2 == r3;
         if ! cc jump .Ldo_trace;
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+# ifdef CONFIG_FUNCTION_GRAPH_TRACER
         /* if the ftrace_graph_return function pointer is not set to
          * the ftrace_stub entry, call prepare_ftrace_return().
          */
@@ -64,7 +126,7 @@ ENTRY(__mcount)
         r3 = [p0];
         cc = r2 == r3;
         if ! cc jump _ftrace_graph_caller;
-#endif
+# endif
 
         r2 = [sp++];
         rts;
@@ -103,6 +165,8 @@ _ftrace_stub:
         rts;
 ENDPROC(__mcount)
 
+#endif
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 /* The prepare_ftrace_return() function is similar to the trace function
  * except it takes a pointer to the location of the frompc.  This is so
@@ -110,6 +174,7 @@ ENDPROC(__mcount)
  * purposes.
  */
 ENTRY(_ftrace_graph_caller)
+# ifndef CONFIG_DYNAMIC_FTRACE
         /* save first/second function arg and the return register */
         [--sp] = r0;
         [--sp] = r1;
@@ -118,9 +183,13 @@ ENTRY(_ftrace_graph_caller)
         /* prepare_ftrace_return(parent, self_addr, frame_pointer) */
         r0 = sp;        /* unsigned long *parent */
         r1 = rets;      /* unsigned long self_addr */
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
+# else
+        r0 = sp;        /* unsigned long *parent */
+        r1 = [sp];      /* unsigned long self_addr */
+# endif
+# ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
         r2 = fp;        /* unsigned long frame_pointer */
-#endif
+# endif
         r0 += 16;       /* skip the 4 local regs on stack */
         r1 += -MCOUNT_INSN_SIZE;
         call _prepare_ftrace_return;
@@ -139,9 +208,9 @@ ENTRY(_return_to_handler)
         [--sp] = r1;
 
         /* get original return address */
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
+# ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
         r0 = fp;        /* Blackfin is sane, so omit this */
-#endif
+# endif
         call _ftrace_return_to_handler;
         rets = r0;