parisc: add ftrace (function and graph tracer) functionality

This patch adds the ftrace debugging functionality to the parisc kernel.
It will currently only work with 64bit kernels, because the gcc options -pg
and -ffunction-sections can't be enabled at the same time and -ffunction-sections
is still needed to be able to link 32bit kernels.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index 4e9dd15e076c..ae3e70cd1e14 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -2185,6 +2185,33 @@ syscall_do_resched:
 ENDPROC(syscall_exit)
 
 
+#ifdef CONFIG_FUNCTION_TRACER
+        .import ftrace_function_trampoline,code
+ENTRY(_mcount)
+        copy    %r3, %arg2
+        b       ftrace_function_trampoline
+        nop
+ENDPROC(_mcount)
+
+ENTRY(return_to_handler)
+        load32  return_trampoline, %rp
+        copy    %ret0, %arg0
+        copy    %ret1, %arg1
+        b       ftrace_return_to_handler
+        nop
+return_trampoline:
+        copy    %ret0, %rp
+        copy    %r23, %ret0
+        copy    %r24, %ret1
+
+.globl ftrace_stub
+ftrace_stub:
+        bv      %r0(%rp)
+        nop
+ENDPROC(return_to_handler)
+#endif  /* CONFIG_FUNCTION_TRACER */
+
+
 get_register:
         /*
          * get_register is used by the non access tlb miss handlers to