4 files changed, 110 insertions, 3 deletions

diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 39c8bc1a006a..d74265cffd86 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -11,4 +11,38 @@ extern void mcount(void);
 
 #endif
 
+#ifndef __ASSEMBLY__
+
+#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
+/*
+ * return_address uses walk_stackframe to do it's work.  If both
+ * CONFIG_FRAME_POINTER=y and CONFIG_ARM_UNWIND=y walk_stackframe uses unwind
+ * information.  For this to work in the function tracer many functions would
+ * have to be marked with __notrace.  So for now just depend on
+ * !CONFIG_ARM_UNWIND.
+ */
+
+void *return_address(unsigned int);
+
+#else
+
+extern inline void *return_address(unsigned int level)
+{
+        return NULL;
+}
+
+#endif
+
+#define HAVE_ARCH_CALLER_ADDR
+
+#define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
+#define CALLER_ADDR1 ((unsigned long)return_address(1))
+#define CALLER_ADDR2 ((unsigned long)return_address(2))
+#define CALLER_ADDR3 ((unsigned long)return_address(3))
+#define CALLER_ADDR4 ((unsigned long)return_address(4))
+#define CALLER_ADDR5 ((unsigned long)return_address(5))
+#define CALLER_ADDR6 ((unsigned long)return_address(6))
+
+#endif /* ifndef __ASSEMBLY__ */
+
 #endif /* _ASM_ARM_FTRACE */
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index ff89d0b3abc5..3213c9382b17 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -8,10 +8,12 @@ ifdef CONFIG_DYNAMIC_FTRACE
 CFLAGS_REMOVE_ftrace.o = -pg
 endif
 
+CFLAGS_REMOVE_return_address.o = -pg
+
 # Object file lists.
 
 obj-y           := compat.o elf.o entry-armv.o entry-common.o irq.o \
-                   process.o ptrace.o setup.o signal.o \
+                   process.o ptrace.o return_address.o setup.o signal.o \
                    sys_arm.o stacktrace.o time.o traps.o
 
 obj-$(CONFIG_ISA_DMA_API)       += dma.o
diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c
new file mode 100644
index 000000000000..df246da4ceca
--- /dev/null
+++ b/arch/arm/kernel/return_address.c
@@ -0,0 +1,71 @@
+/*
+ * arch/arm/kernel/return_address.c
+ *
+ * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
+ * for Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#include <linux/module.h>
+
+#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
+#include <linux/sched.h>
+
+#include <asm/stacktrace.h>
+
+struct return_address_data {
+        unsigned int level;
+        void *addr;
+};
+
+static int save_return_addr(struct stackframe *frame, void *d)
+{
+        struct return_address_data *data = d;
+
+        if (!data->level) {
+                data->addr = (void *)frame->lr;
+
+                return 1;
+        } else {
+                --data->level;
+                return 0;
+        }
+}
+
+void *return_address(unsigned int level)
+{
+        struct return_address_data data;
+        struct stackframe frame;
+        register unsigned long current_sp asm ("sp");
+
+        data.level = level + 1;
+
+        frame.fp = (unsigned long)__builtin_frame_address(0);
+        frame.sp = current_sp;
+        frame.lr = (unsigned long)__builtin_return_address(0);
+        frame.pc = (unsigned long)return_address;
+
+        walk_stackframe(&frame, save_return_addr, &data);
+
+        if (!data.level)
+                return data.addr;
+        else
+                return NULL;
+}
+
+#else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
+
+#if defined(CONFIG_ARM_UNWIND)
+#warning "TODO: return_address should use unwind tables"
+#endif
+
+void *return_address(unsigned int level)
+{
+        return NULL;
+}
+
+#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */
+
+EXPORT_SYMBOL_GPL(return_address);
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 9f444e5cc165..20b7411e47fd 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -21,7 +21,7 @@
  * Note that with framepointer enabled, even the leaf functions have the same
  * prologue and epilogue, therefore we can ignore the LR value in this case.
  */
-int unwind_frame(struct stackframe *frame)
+int notrace unwind_frame(struct stackframe *frame)
 {
         unsigned long high, low;
         unsigned long fp = frame->fp;
@@ -43,7 +43,7 @@ int unwind_frame(struct stackframe *frame)
 }
 #endif
 
-void walk_stackframe(struct stackframe *frame,
+void notrace walk_stackframe(struct stackframe *frame,
                      int (*fn)(struct stackframe *, void *), void *data)
 {
         while (1) {