3 files changed, 86 insertions, 1 deletions

diff --git a/arch/avr32/oprofile/Makefile b/arch/avr32/oprofile/Makefile
index 1fe81c3c1e86..e0eb520e0287 100644
--- a/arch/avr32/oprofile/Makefile
+++ b/arch/avr32/oprofile/Makefile
@@ -5,4 +5,4 @@ oprofile-y		:= $(addprefix ../../../drivers/oprofile/,	\
                                 event_buffer.o oprofile_files.o         \
                                 oprofilefs.o oprofile_stats.o           \
                                 timer_int.o)
-oprofile-y              += op_model_avr32.o
+oprofile-y              += op_model_avr32.o backtrace.o
diff --git a/arch/avr32/oprofile/backtrace.c b/arch/avr32/oprofile/backtrace.c
new file mode 100644
index 000000000000..75d9ad6f99cf
--- /dev/null
+++ b/arch/avr32/oprofile/backtrace.c
@@ -0,0 +1,81 @@
+/*
+ * AVR32 specific backtracing code for oprofile
+ *
+ * Copyright 2008 Weinmann GmbH
+ *
+ * Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ * Based on i386 oprofile backtrace code by John Levon and David Smith
+ *
+ * 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/oprofile.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+
+/* The first two words of each frame on the stack look like this if we have
+ * frame pointers */
+struct frame_head {
+        unsigned long lr;
+        struct frame_head *fp;
+};
+
+/* copied from arch/avr32/kernel/process.c */
+static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
+{
+        return (p > (unsigned long)tinfo)
+                && (p < (unsigned long)tinfo + THREAD_SIZE - 3);
+}
+
+/* copied from arch/x86/oprofile/backtrace.c */
+static struct frame_head *dump_user_backtrace(struct frame_head *head)
+{
+        struct frame_head bufhead[2];
+
+        /* Also check accessibility of one struct frame_head beyond */
+        if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
+                return NULL;
+        if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+                return NULL;
+
+        oprofile_add_trace(bufhead[0].lr);
+
+        /* frame pointers should strictly progress back up the stack
+         * (towards higher addresses) */
+        if (bufhead[0].fp <= head)
+                return NULL;
+
+        return bufhead[0].fp;
+}
+
+void avr32_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+        /* Get first frame pointer */
+        struct frame_head *head = (struct frame_head *)(regs->r7);
+
+        if (!user_mode(regs)) {
+#ifdef CONFIG_FRAME_POINTER
+                /*
+                 * Traverse the kernel stack from frame to frame up to
+                 * "depth" steps.
+                 */
+                while (depth-- && valid_stack_ptr(task_thread_info(current),
+                                                  (unsigned long)head)) {
+                        oprofile_add_trace(head->lr);
+                        if (head->fp <= head)
+                                break;
+                        head = head->fp;
+                }
+#endif
+        } else {
+                /* Assume we have frame pointers in user mode process */
+                while (depth-- && head)
+                        head = dump_user_backtrace(head);
+        }
+}
+
+
diff --git a/arch/avr32/oprofile/op_model_avr32.c b/arch/avr32/oprofile/op_model_avr32.c
index df42325c7f81..a3e9b3c4845a 100644
--- a/arch/avr32/oprofile/op_model_avr32.c
+++ b/arch/avr32/oprofile/op_model_avr32.c
@@ -22,6 +22,8 @@
 #define AVR32_PERFCTR_IRQ_GROUP 0
 #define AVR32_PERFCTR_IRQ_LINE  1
 
+void avr32_backtrace(struct pt_regs * const regs, unsigned int depth);
+
 enum { PCCNT, PCNT0, PCNT1, NR_counter };
 
 struct avr32_perf_counter {
@@ -223,6 +225,8 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
         memcpy(ops, &avr32_perf_counter_ops,
                         sizeof(struct oprofile_operations));
 
+        ops->backtrace = avr32_backtrace;
+
         printk(KERN_INFO "oprofile: using AVR32 performance monitoring.\n");
 
         return 0;