ftrace: core support for ARM

Core ftrace support for the ARM architecture, which includes support
for dynamic function tracing.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 47 insertions, 0 deletions

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 597ed00a08d8..8f79a4789ed4 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -99,6 +99,53 @@ ENTRY(ret_from_fork)
 #undef CALL
 #define CALL(x) .long x
 
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+ENTRY(mcount)
+        stmdb sp!, {r0-r3, lr}
+        mov r0, lr
+
+        .globl mcount_call
+mcount_call:
+        bl ftrace_stub
+        ldmia sp!, {r0-r3, pc}
+
+ENTRY(ftrace_caller)
+        stmdb sp!, {r0-r3, lr}
+        ldr r1, [fp, #-4]
+        mov r0, lr
+
+        .globl ftrace_call
+ftrace_call:
+        bl ftrace_stub
+        ldmia sp!, {r0-r3, pc}
+
+#else
+
+ENTRY(mcount)
+        stmdb sp!, {r0-r3, lr}
+        ldr r0, =ftrace_trace_function
+        ldr r2, [r0]
+        adr r0, ftrace_stub
+        cmp r0, r2
+        bne trace
+        ldmia sp!, {r0-r3, pc}
+
+trace:
+        ldr r1, [fp, #-4]
+        mov r0, lr
+        mov lr, pc
+        mov pc, r2
+        ldmia sp!, {r0-r3, pc}
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+        .globl ftrace_stub
+ftrace_stub:
+        mov pc, lr
+
+#endif /* CONFIG_FTRACE */
+
 /*=============================================================================
  * SWI handler
  *-----------------------------------------------------------------------------