sh: Function graph tracer support

Add both dynamic and static function graph tracer support for sh.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

2 files changed, 117 insertions, 1 deletions

diff --git a/arch/sh/lib/Makefile b/arch/sh/lib/Makefile
index aaea580b65bb..19328d90a2d1 100644
--- a/arch/sh/lib/Makefile
+++ b/arch/sh/lib/Makefile
@@ -25,6 +25,7 @@ memcpy-$(CONFIG_CPU_SH4)	:= memcpy-sh4.o
 
 lib-$(CONFIG_MMU)               += copy_page.o clear_page.o
 lib-$(CONFIG_FUNCTION_TRACER)   += mcount.o
+lib-$(CONFIG_FUNCTION_GRAPH_TRACER) += mcount.o
 lib-y                           += $(memcpy-y) $(udivsi3-y)
 
 EXTRA_CFLAGS += -Werror
diff --git a/arch/sh/lib/mcount.S b/arch/sh/lib/mcount.S
index 8596483f7b41..bd3ec648becc 100644
--- a/arch/sh/lib/mcount.S
+++ b/arch/sh/lib/mcount.S
@@ -111,14 +111,62 @@ mcount_call:
         jsr     @r6
          nop
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        mov.l   .Lftrace_graph_return, r6
+        mov.l   .Lftrace_stub, r7
+        cmp/eq  r6, r7
+        bt      1f
+
+        mov.l   .Lftrace_graph_caller, r0
+        jmp     @r0
+         nop
+
+1:
+        mov.l   .Lftrace_graph_entry, r6
+        mov.l   .Lftrace_graph_entry_stub, r7
+        cmp/eq  r6, r7
+        bt      skip_trace
+
+        mov.l   .Lftrace_graph_caller, r0
+        jmp     @r0
+         nop
+
+        .align 2
+.Lftrace_graph_return:
+        .long   ftrace_graph_return
+.Lftrace_graph_entry:
+        .long   ftrace_graph_entry
+.Lftrace_graph_entry_stub:
+        .long   ftrace_graph_entry_stub
+.Lftrace_graph_caller:
+        .long   ftrace_graph_caller
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+        .globl skip_trace
 skip_trace:
         MCOUNT_LEAVE()
 
         .align 2
 .Lftrace_trace_function:
-        .long   ftrace_trace_function
+        .long   ftrace_trace_function
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/*
+ * NOTE: Do not move either ftrace_graph_call or ftrace_caller
+ * as this will affect the calculation of GRAPH_INSN_OFFSET.
+ */
+        .globl ftrace_graph_call
+ftrace_graph_call:
+        mov.l   .Lskip_trace, r0
+        jmp     @r0
+         nop
+
+        .align 2
+.Lskip_trace:
+        .long   skip_trace
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
         .globl ftrace_caller
 ftrace_caller:
         mov.l   .Lfunction_trace_stop, r0
@@ -136,7 +184,12 @@ ftrace_call:
         jsr     @r6
          nop
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        bra     ftrace_graph_call
+         nop
+#else
         MCOUNT_LEAVE()
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 /*
@@ -188,3 +241,65 @@ stack_panic:
 .Lpanic_str:
         .string "Stack error"
 #endif /* CONFIG_STACK_DEBUG */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        .globl  ftrace_graph_caller
+ftrace_graph_caller:
+        mov.l   2f, r0
+        mov.l   @r0, r0
+        tst     r0, r0
+        bt      1f
+
+        mov.l   3f, r1
+        jmp     @r1
+         nop
+1:
+        /*
+         * MCOUNT_ENTER() pushed 5 registers onto the stack, so
+         * the stack address containing our return address is
+         * r15 + 20.
+         */
+        mov     #20, r0
+        add     r15, r0
+        mov     r0, r4
+
+        mov.l   .Lprepare_ftrace_return, r0
+        jsr     @r0
+         nop
+
+        MCOUNT_LEAVE()
+
+        .align 2
+2:      .long   function_trace_stop
+3:      .long   skip_trace
+.Lprepare_ftrace_return:
+        .long   prepare_ftrace_return
+
+        .globl  return_to_handler
+return_to_handler:
+        /*
+         * Save the return values.
+         */
+        mov.l   r0, @-r15
+        mov.l   r1, @-r15
+
+        mov     #0, r4
+
+        mov.l   .Lftrace_return_to_handler, r0
+        jsr     @r0
+         nop
+
+        /*
+         * The return value from ftrace_return_handler has the real
+         * address that we should return to.
+         */
+        lds     r0, pr
+        mov.l   @r15+, r1
+        rts
+         mov.l  @r15+, r0
+
+
+        .align 2
+.Lftrace_return_to_handler:
+        .long   ftrace_return_to_handler
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */