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-rw-r--r--arch/sh/include/asm/unwinder.h25
-rw-r--r--arch/sh/kernel/Makefile_324
-rw-r--r--arch/sh/kernel/Makefile_642
-rw-r--r--arch/sh/kernel/unwinder.c162
4 files changed, 190 insertions, 3 deletions
diff --git a/arch/sh/include/asm/unwinder.h b/arch/sh/include/asm/unwinder.h
new file mode 100644
index 00000000000..3dc551453e2
--- /dev/null
+++ b/arch/sh/include/asm/unwinder.h
@@ -0,0 +1,25 @@
+#ifndef _LINUX_UNWINDER_H
+#define _LINUX_UNWINDER_H
+
+#include <asm/stacktrace.h>
+
+struct unwinder {
+ const char *name;
+ struct list_head list;
+ int rating;
+ void (*dump)(struct task_struct *, struct pt_regs *,
+ unsigned long *, const struct stacktrace_ops *, void *);
+};
+
+extern int unwinder_init(void);
+extern int unwinder_register(struct unwinder *);
+
+extern void unwind_stack(struct task_struct *, struct pt_regs *,
+ unsigned long *, const struct stacktrace_ops *,
+ void *);
+
+extern void stack_reader_dump(struct task_struct *, struct pt_regs *,
+ unsigned long *, const struct stacktrace_ops *,
+ void *);
+
+#endif /* _LINUX_UNWINDER_H */
diff --git a/arch/sh/kernel/Makefile_32 b/arch/sh/kernel/Makefile_32
index 6b32de701a7..37a3b7704fc 100644
--- a/arch/sh/kernel/Makefile_32
+++ b/arch/sh/kernel/Makefile_32
@@ -11,8 +11,8 @@ endif
obj-y := debugtraps.o dumpstack.o idle.o io.o io_generic.o irq.o \
machvec.o process_32.o ptrace_32.o setup.o signal_32.o \
- sys_sh.o sys_sh32.o syscalls_32.o time.o topology.o \
- traps.o traps_32.o
+ sys_sh.o sys_sh32.o syscalls_32.o time.o topology.o \
+ traps.o traps_32.o unwinder.o
obj-y += cpu/
obj-$(CONFIG_VSYSCALL) += vsyscall/
diff --git a/arch/sh/kernel/Makefile_64 b/arch/sh/kernel/Makefile_64
index 67b9f6c6326..00b73e7598c 100644
--- a/arch/sh/kernel/Makefile_64
+++ b/arch/sh/kernel/Makefile_64
@@ -2,7 +2,7 @@ extra-y := head_64.o init_task.o vmlinux.lds
obj-y := debugtraps.o idle.o io.o io_generic.o irq.o machvec.o process_64.o \
ptrace_64.o setup.o signal_64.o sys_sh.o sys_sh64.o \
- syscalls_64.o time.o topology.o traps.o traps_64.o
+ syscalls_64.o time.o topology.o traps.o traps_64.o unwinder.o
obj-y += cpu/
obj-$(CONFIG_SMP) += smp.o
diff --git a/arch/sh/kernel/unwinder.c b/arch/sh/kernel/unwinder.c
new file mode 100644
index 00000000000..2b30fa28b44
--- /dev/null
+++ b/arch/sh/kernel/unwinder.c
@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) 2009 Matt Fleming
+ *
+ * Based, in part, on kernel/time/clocksource.c.
+ *
+ * This file provides arbitration code for stack unwinders.
+ *
+ * Multiple stack unwinders can be available on a system, usually with
+ * the most accurate unwinder being the currently active one.
+ */
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <asm/unwinder.h>
+#include <asm/atomic.h>
+
+/*
+ * This is the most basic stack unwinder an architecture can
+ * provide. For architectures without reliable frame pointers, e.g.
+ * RISC CPUs, it can be implemented by looking through the stack for
+ * addresses that lie within the kernel text section.
+ *
+ * Other CPUs, e.g. x86, can use their frame pointer register to
+ * construct more accurate stack traces.
+ */
+static struct list_head unwinder_list;
+static struct unwinder stack_reader = {
+ .name = "stack-reader",
+ .dump = stack_reader_dump,
+ .rating = 50,
+ .list = {
+ .next = &unwinder_list,
+ .prev = &unwinder_list,
+ },
+};
+
+/*
+ * "curr_unwinder" points to the stack unwinder currently in use. This
+ * is the unwinder with the highest rating.
+ *
+ * "unwinder_list" is a linked-list of all available unwinders, sorted
+ * by rating.
+ *
+ * All modifications of "curr_unwinder" and "unwinder_list" must be
+ * performed whilst holding "unwinder_lock".
+ */
+static struct unwinder *curr_unwinder = &stack_reader;
+
+static struct list_head unwinder_list = {
+ .next = &stack_reader.list,
+ .prev = &stack_reader.list,
+};
+
+static DEFINE_SPINLOCK(unwinder_lock);
+
+static atomic_t unwinder_running = ATOMIC_INIT(0);
+
+/**
+ * select_unwinder - Select the best registered stack unwinder.
+ *
+ * Private function. Must hold unwinder_lock when called.
+ *
+ * Select the stack unwinder with the best rating. This is useful for
+ * setting up curr_unwinder.
+ */
+static struct unwinder *select_unwinder(void)
+{
+ struct unwinder *best;
+
+ if (list_empty(&unwinder_list))
+ return NULL;
+
+ best = list_entry(unwinder_list.next, struct unwinder, list);
+ if (best == curr_unwinder)
+ return NULL;
+
+ return best;
+}
+
+/*
+ * Enqueue the stack unwinder sorted by rating.
+ */
+static int unwinder_enqueue(struct unwinder *ops)
+{
+ struct list_head *tmp, *entry = &unwinder_list;
+
+ list_for_each(tmp, &unwinder_list) {
+ struct unwinder *o;
+
+ o = list_entry(tmp, struct unwinder, list);
+ if (o == ops)
+ return -EBUSY;
+ /* Keep track of the place, where to insert */
+ if (o->rating >= ops->rating)
+ entry = tmp;
+ }
+ list_add(&ops->list, entry);
+
+ return 0;
+}
+
+/**
+ * unwinder_register - Used to install new stack unwinder
+ * @u: unwinder to be registered
+ *
+ * Install the new stack unwinder on the unwinder list, which is sorted
+ * by rating.
+ *
+ * Returns -EBUSY if registration fails, zero otherwise.
+ */
+int unwinder_register(struct unwinder *u)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&unwinder_lock, flags);
+ ret = unwinder_enqueue(u);
+ if (!ret)
+ curr_unwinder = select_unwinder();
+ spin_unlock_irqrestore(&unwinder_lock, flags);
+
+ return ret;
+}
+
+/*
+ * Unwind the call stack and pass information to the stacktrace_ops
+ * functions. Also handle the case where we need to switch to a new
+ * stack dumper because the current one faulted unexpectedly.
+ */
+void unwind_stack(struct task_struct *task, struct pt_regs *regs,
+ unsigned long *sp, const struct stacktrace_ops *ops,
+ void *data)
+{
+ unsigned long flags;
+
+ /*
+ * The problem with unwinders with high ratings is that they are
+ * inherently more complicated than the simple ones with lower
+ * ratings. We are therefore more likely to fault in the
+ * complicated ones, e.g. hitting BUG()s. If we fault in the
+ * code for the current stack unwinder we try to downgrade to
+ * one with a lower rating.
+ *
+ * Hopefully this will give us a semi-reliable stacktrace so we
+ * can diagnose why curr_unwinder->dump() faulted.
+ */
+ if (atomic_inc_return(&unwinder_running) != 1) {
+ spin_lock_irqsave(&unwinder_lock, flags);
+
+ if (!list_is_singular(&unwinder_list)) {
+ list_del(&curr_unwinder->list);
+ curr_unwinder = select_unwinder();
+ }
+
+ spin_unlock_irqrestore(&unwinder_lock, flags);
+ atomic_dec(&unwinder_running);
+ }
+
+ curr_unwinder->dump(task, regs, sp, ops, data);
+
+ atomic_dec(&unwinder_running);
+}