[PATCH] x86_64: reliable stack trace support (x86-64)

These are the x86_64-specific pieces to enable reliable stack traces. The
only restriction with this is that it currently cannot unwind across the
interrupt->normal stack boundary, as that transition is lacking proper
annotation.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 106 insertions, 0 deletions

diff --git a/include/asm-x86_64/unwind.h b/include/asm-x86_64/unwind.h
new file mode 100644
index 000000000000..4f61de246179
--- /dev/null
+++ b/include/asm-x86_64/unwind.h
@@ -0,0 +1,106 @@
+#ifndef _ASM_X86_64_UNWIND_H
+#define _ASM_X86_64_UNWIND_H
+
+/*
+ * Copyright (C) 2002-2006 Novell, Inc.
+ *      Jan Beulich <jbeulich@novell.com>
+ * This code is released under version 2 of the GNU GPL.
+ */
+
+#ifdef CONFIG_STACK_UNWIND
+
+#include <linux/sched.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+#include <asm/vsyscall.h>
+
+struct unwind_frame_info
+{
+        struct pt_regs regs;
+        struct task_struct *task;
+};
+
+#define UNW_PC(frame)        (frame)->regs.rip
+#define UNW_SP(frame)        (frame)->regs.rsp
+#ifdef CONFIG_FRAME_POINTER
+#define UNW_FP(frame)        (frame)->regs.rbp
+#define FRAME_RETADDR_OFFSET 8
+#define FRAME_LINK_OFFSET    0
+#define STACK_BOTTOM(tsk)    (((tsk)->thread.rsp0 - 1) & ~(THREAD_SIZE - 1))
+#define STACK_TOP(tsk)       ((tsk)->thread.rsp0)
+#endif
+/* Might need to account for the special exception and interrupt handling
+   stacks here, since normally
+        EXCEPTION_STACK_ORDER < THREAD_ORDER < IRQSTACK_ORDER,
+   but the construct is needed only for getting across the stack switch to
+   the interrupt stack - thus considering the IRQ stack itself is unnecessary,
+   and the overhead of comparing against all exception handling stacks seems
+   not desirable. */
+#define STACK_LIMIT(ptr)     (((ptr) - 1) & ~(THREAD_SIZE - 1))
+
+#define UNW_REGISTER_INFO \
+        PTREGS_INFO(rax), \
+        PTREGS_INFO(rdx), \
+        PTREGS_INFO(rcx), \
+        PTREGS_INFO(rbx), \
+        PTREGS_INFO(rsi), \
+        PTREGS_INFO(rdi), \
+        PTREGS_INFO(rbp), \
+        PTREGS_INFO(rsp), \
+        PTREGS_INFO(r8), \
+        PTREGS_INFO(r9), \
+        PTREGS_INFO(r10), \
+        PTREGS_INFO(r11), \
+        PTREGS_INFO(r12), \
+        PTREGS_INFO(r13), \
+        PTREGS_INFO(r14), \
+        PTREGS_INFO(r15), \
+        PTREGS_INFO(rip)
+
+static inline void arch_unw_init_frame_info(struct unwind_frame_info *info,
+                                            /*const*/ struct pt_regs *regs)
+{
+        info->regs = *regs;
+}
+
+static inline void arch_unw_init_blocked(struct unwind_frame_info *info)
+{
+        extern const char thread_return[];
+
+        memset(&info->regs, 0, sizeof(info->regs));
+        info->regs.rip = (unsigned long)thread_return;
+        info->regs.cs = __KERNEL_CS;
+        __get_user(info->regs.rbp, (unsigned long *)info->task->thread.rsp);
+        info->regs.rsp = info->task->thread.rsp;
+        info->regs.ss = __KERNEL_DS;
+}
+
+extern void arch_unwind_init_running(struct unwind_frame_info *,
+                                     void (*callback)(struct unwind_frame_info *,
+                                                      void *arg),
+                                     void *arg);
+
+static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
+{
+#if 0 /* This can only work when selector register saves/restores
+         are properly annotated (and tracked in UNW_REGISTER_INFO). */
+        return user_mode(&info->regs);
+#else
+        return (long)info->regs.rip >= 0
+               || (info->regs.rip >= VSYSCALL_START && info->regs.rip < VSYSCALL_END)
+               || (long)info->regs.rsp >= 0;
+#endif
+}
+
+#else
+
+#define UNW_PC(frame) ((void)(frame), 0)
+
+static inline int arch_unw_user_mode(const void *info)
+{
+        return 0;
+}
+
+#endif
+
+#endif /* _ASM_X86_64_UNWIND_H */