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/* -*- 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. */
#if !defined(STAPCONF_KERNEL_STACKTRACE)
static void _stp_stack_print_fallback(unsigned long stack, int verbose, int levels)
{
unsigned long addr;
while (levels && stack & (THREAD_SIZE-1)) {
if (unlikely(_stp_read_address(addr, (unsigned long *)stack, KERNEL_DS))) {
/* cannot access stack. give up. */
return;
}
if (_stp_func_print(addr, verbose, 0, NULL))
levels--;
stack++;
}
}
#endif
static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels,
struct task_struct *tsk, struct uretprobe_instance *ri)
{
unsigned long context = (unsigned long)®_SP(regs) & ~(THREAD_SIZE - 1);
#ifdef STP_USE_FRAME_POINTER
unsigned long addr;
unsigned long next_fp, fp = REG_FP(regs);
while (levels && _stp_valid_stack_ptr(context, (unsigned long)fp)) {
if (unlikely(_stp_read_address(addr, (unsigned long *)(fp + 4), KERNEL_DS))) {
/* cannot access stack. give up. */
return;
}
_stp_func_print(addr, verbose, 1, NULL);
if (unlikely(_stp_read_address(next_fp, (unsigned long *)fp, KERNEL_DS))) {
/* cannot access stack. give up. */
return;
}
levels--;
/* frame pointers move upwards */
if (next_fp <= fp)
break;
fp = next_fp;
}
#else
#ifdef STP_USE_DWARF_UNWINDER
struct unwind_frame_info info;
arch_unw_init_frame_info(&info, regs);
while (levels && (tsk || !arch_unw_user_mode(&info))) {
int ret = unwind(&info, tsk);
#ifdef CONFIG_UTRACE
unsigned long maybe_pc = 0;
if (ri) {
maybe_pc = uprobe_get_pc(ri, UNW_PC(&info),
UNW_SP(&info));
if (!maybe_pc)
printk("SYSTEMTAP ERROR: uprobe_get_return returned 0\n");
else
UNW_PC(&info) = maybe_pc;
}
#endif
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, tsk);
levels--;
if (UNW_PC(&info) != _stp_kretprobe_trampoline)
continue;
}
/* If an error happened or we hit a kretprobe trampoline,
* use fallback backtrace, unless user task backtrace.
* FIXME: is there a way to unwind across kretprobe
* trampolines? PR9999. */
if ((ret < 0
|| UNW_PC(&info) == _stp_kretprobe_trampoline)
&& ! (tsk || arch_unw_user_mode(&info)))
_stp_stack_print_fallback(UNW_SP(&info), verbose, levels);
return;
}
#else /* ! STP_USE_DWARF_UNWINDER */
_stp_stack_print_fallback((unsigned long)®_SP(regs), verbose, levels);
#endif /* STP_USE_FRAME_POINTER */
#endif
}
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