[PATCH] x86_64: reliable stack trace support
These are the generic bits needed to enable reliable stack traces based
on Dwarf2-like (.eh_frame) unwind information. Subsequent patches will
enable x86-64 and i386 to make use of this.
Thanks to Andi Kleen and Ingo Molnar, who pointed out several possibilities
for improvement.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3c5e4c2..5c1ec1f 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -32,6 +32,7 @@
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#define ALIGN(x,a) (((x)+(a)-1)&~((a)-1))
+#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
#define KERN_EMERG "<0>" /* system is unusable */
#define KERN_ALERT "<1>" /* action must be taken immediately */
@@ -336,6 +337,12 @@
/* Force a compilation error if condition is true */
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+/* Force a compilation error if condition is true, but also produce a
+ result (of value 0 and type size_t), so the expression can be used
+ e.g. in a structure initializer (or where-ever else comma expressions
+ aren't permitted). */
+#define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1)
+
/* Trap pasters of __FUNCTION__ at compile-time */
#define __FUNCTION__ (__func__)
diff --git a/include/linux/module.h b/include/linux/module.h
index 2d36609..9ebbb74 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -285,6 +285,9 @@
/* The size of the executable code in each section. */
unsigned long init_text_size, core_text_size;
+ /* The handle returned from unwind_add_table. */
+ void *unwind_info;
+
/* Arch-specific module values */
struct mod_arch_specific arch;
diff --git a/include/linux/unwind.h b/include/linux/unwind.h
new file mode 100644
index 0000000..0295aa7
--- /dev/null
+++ b/include/linux/unwind.h
@@ -0,0 +1,119 @@
+#ifndef _LINUX_UNWIND_H
+#define _LINUX_UNWIND_H
+
+/*
+ * Copyright (C) 2002-2006 Novell, Inc.
+ * Jan Beulich <jbeulich@novell.com>
+ * This code is released under version 2 of the GNU GPL.
+ *
+ * A simple API for unwinding kernel stacks. This is used for
+ * debugging and error reporting purposes. The kernel doesn't need
+ * full-blown stack unwinding with all the bells and whistles, so there
+ * is not much point in implementing the full Dwarf2 unwind API.
+ */
+
+#include <linux/config.h>
+
+struct module;
+
+#ifdef CONFIG_STACK_UNWIND
+
+#include <asm/unwind.h>
+
+#ifndef ARCH_UNWIND_SECTION_NAME
+#define ARCH_UNWIND_SECTION_NAME ".eh_frame"
+#endif
+
+/*
+ * Initialize unwind support.
+ */
+extern void unwind_init(void);
+
+extern void *unwind_add_table(struct module *,
+ const void *table_start,
+ unsigned long table_size);
+
+extern void unwind_remove_table(void *handle, int init_only);
+
+extern int unwind_init_frame_info(struct unwind_frame_info *,
+ struct task_struct *,
+ /*const*/ struct pt_regs *);
+
+/*
+ * Prepare to unwind a blocked task.
+ */
+extern int unwind_init_blocked(struct unwind_frame_info *,
+ struct task_struct *);
+
+/*
+ * Prepare to unwind the currently running thread.
+ */
+extern int unwind_init_running(struct unwind_frame_info *,
+ asmlinkage void (*callback)(struct unwind_frame_info *,
+ void *arg),
+ void *arg);
+
+/*
+ * Unwind to previous to frame. Returns 0 if successful, negative
+ * number in case of an error.
+ */
+extern int unwind(struct unwind_frame_info *);
+
+/*
+ * Unwind until the return pointer is in user-land (or until an error
+ * occurs). Returns 0 if successful, negative number in case of
+ * error.
+ */
+extern int unwind_to_user(struct unwind_frame_info *);
+
+#else
+
+struct unwind_frame_info {};
+
+static inline void unwind_init(void) {}
+
+static inline void *unwind_add_table(struct module *mod,
+ const void *table_start,
+ unsigned long table_size)
+{
+ return NULL;
+}
+
+static inline void unwind_remove_table(void *handle, int init_only)
+{
+}
+
+static inline int unwind_init_frame_info(struct unwind_frame_info *info,
+ struct task_struct *tsk,
+ const struct pt_regs *regs)
+{
+ return -ENOSYS;
+}
+
+static inline int unwind_init_blocked(struct unwind_frame_info *info,
+ struct task_struct *tsk)
+{
+ return -ENOSYS;
+}
+
+static inline int unwind_init_running(struct unwind_frame_info *info,
+ asmlinkage void (*cb)(struct unwind_frame_info *,
+ void *arg),
+ void *arg)
+{
+ return -ENOSYS;
+}
+
+static inline int unwind(struct unwind_frame_info *info)
+{
+ return -ENOSYS;
+}
+
+static inline int unwind_to_user(struct unwind_frame_info *info)
+{
+ return -ENOSYS;
+}
+
+#endif
+
+#endif /* _LINUX_UNWIND_H */