[PATCH] i386: reliable stack trace support (i386)

These are the i386-specific pieces to enable reliable stack traces. This is
going to be even more useful once CFI annotations get added to he assembly
code, namely to entry.S.

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

2 files changed, 99 insertions, 1 deletions

diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index b796210..55ea992 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -555,7 +555,7 @@ extern void prepare_to_copy(struct task_struct *tsk);
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 extern unsigned long thread_saved_pc(struct task_struct *tsk);
-void show_trace(struct task_struct *task, unsigned long *stack);
+void show_trace(struct task_struct *task, struct pt_regs *regs, unsigned long *stack);
 
 unsigned long get_wchan(struct task_struct *p);
 
diff --git a/include/asm-i386/unwind.h b/include/asm-i386/unwind.h
new file mode 100644
index 0000000..1c07689
--- /dev/null
+++ b/include/asm-i386/unwind.h
@@ -0,0 +1,98 @@
+#ifndef _ASM_I386_UNWIND_H
+#define _ASM_I386_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/fixmap.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+
+struct unwind_frame_info
+{
+	struct pt_regs regs;
+	struct task_struct *task;
+};
+
+#define UNW_PC(frame)        (frame)->regs.eip
+#define UNW_SP(frame)        (frame)->regs.esp
+#ifdef CONFIG_FRAME_POINTER
+#define UNW_FP(frame)        (frame)->regs.ebp
+#define FRAME_RETADDR_OFFSET 4
+#define FRAME_LINK_OFFSET    0
+#define STACK_BOTTOM(tsk)    STACK_LIMIT((tsk)->thread.esp0)
+#define STACK_TOP(tsk)       ((tsk)->thread.esp0)
+#endif
+#define STACK_LIMIT(ptr)     (((ptr) - 1) & ~(THREAD_SIZE - 1))
+
+#define UNW_REGISTER_INFO \
+	PTREGS_INFO(eax), \
+	PTREGS_INFO(ecx), \
+	PTREGS_INFO(edx), \
+	PTREGS_INFO(ebx), \
+	PTREGS_INFO(esp), \
+	PTREGS_INFO(ebp), \
+	PTREGS_INFO(esi), \
+	PTREGS_INFO(edi), \
+	PTREGS_INFO(eip)
+
+static inline void arch_unw_init_frame_info(struct unwind_frame_info *info,
+                                            /*const*/ struct pt_regs *regs)
+{
+	if (user_mode_vm(regs))
+		info->regs = *regs;
+	else {
+		memcpy(&info->regs, regs, offsetof(struct pt_regs, esp));
+		info->regs.esp = (unsigned long)&regs->esp;
+		info->regs.xss = __KERNEL_DS;
+	}
+}
+
+static inline void arch_unw_init_blocked(struct unwind_frame_info *info)
+{
+	memset(&info->regs, 0, sizeof(info->regs));
+	info->regs.eip = info->task->thread.eip;
+	info->regs.xcs = __KERNEL_CS;
+	__get_user(info->regs.ebp, (long *)info->task->thread.esp);
+	info->regs.esp = info->task->thread.esp;
+	info->regs.xss = __KERNEL_DS;
+	info->regs.xds = __USER_DS;
+	info->regs.xes = __USER_DS;
+}
+
+extern asmlinkage void arch_unwind_init_running(struct unwind_frame_info *,
+                                                asmlinkage 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 and EFLAGS saves/restores
+         are properly annotated (and tracked in UNW_REGISTER_INFO). */
+	return user_mode_vm(&info->regs);
+#else
+	return info->regs.eip < PAGE_OFFSET
+	       || (info->regs.eip >= __fix_to_virt(FIX_VSYSCALL)
+	            && info->regs.eip < __fix_to_virt(FIX_VSYSCALL) + PAGE_SIZE)
+	       || info->regs.esp < PAGE_OFFSET;
+#endif
+}
+
+#else
+
+#define UNW_PC(frame) ((void)(frame), 0)
+
+static inline int arch_unw_user_mode(const void *info)
+{
+	return 0;
+}
+
+#endif
+
+#endif /* _ASM_I386_UNWIND_H */