/* -*- linux-c -*-
 * i386 stack tracing functions
 * Copyright (C) 2005-2008 Red Hat Inc.
 *
 * This file is part of systemtap, and is free software.  You can
 * redistribute it and/or modify it under the terms of the GNU General
 * Public License (GPL); either version 2, or (at your option) any
 * later version.
 */

static int _stp_valid_stack_ptr(unsigned long context, unsigned long p)
{
	return	p > context && p < context + THREAD_SIZE - 3;
}

/* DWARF unwinder failed.  Just dump intereting addresses on kernel stack. */
static void _stp_stack_print_fallback(unsigned long context, unsigned long stack, int verbose)
{
	unsigned long addr;
	while (_stp_valid_stack_ptr(context, stack)) {
		if (unlikely(_stp_read_address(addr, (unsigned long *)stack, KERNEL_DS))) {
			/* cannot access stack.  give up. */
			return;
		}
		_stp_func_print(addr, verbose, 0);
		stack++;
	}
}

static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
{
	unsigned long *stack = (unsigned long *)&REG_SP(regs);
	unsigned long context = (unsigned long)stack & ~(THREAD_SIZE - 1);

#ifdef	CONFIG_FRAME_POINTER
	/* FIXME: need to use _stp_func_print() and safe copy */
	unsigned long addr;
	
#ifdef STAPCONF_X86_UNIREGS
	unsigned long ebp = regs->bp;
#else
	unsigned long ebp = regs->ebp;
#endif /* STAPCONF_X86_UNIREGS */
	
	while (_stp_valid_stack_ptr(context, (unsigned long)ebp)) {
		if (unlikely(_stp_read_address(addr, (unsigned long *)(ebp + 4), KERNEL_DS))) {
			/* cannot access stack.  give up. */
			return;
		}
		if (verbose) {
			_stp_print_char(' ');
			_stp_symbol_print (addr);
			_stp_print_char('\n');
		} else
			_stp_printf ("0x%08lx ", addr);
		ebp = *(unsigned long *)ebp;
	}
#else
	struct unwind_frame_info info;
	arch_unw_init_frame_info(&info, regs);
	
	while (!arch_unw_user_mode(&info)) {
		int ret = unwind(&info);
		dbug_unwind(1, "ret=%d PC=%lx SP=%lx\n", ret, UNW_PC(&info), UNW_SP(&info));
		if (ret == 0) {
			_stp_func_print(UNW_PC(&info), verbose, 1);
			continue;
		}
		/* If an error happened or we hit a kretprobe trampoline, use fallback backtrace */
		/* FIXME: is there a way to unwind across kretprobe trampolines? */
		if (ret < 0 || (ret > 0 && UNW_PC(&info) == _stp_kretprobe_trampoline))
			_stp_stack_print_fallback(context, UNW_SP(&info), verbose);
		break;
	}
#endif /* CONFIG_FRAME_POINTER */
}