static void __stp_dwarf_stack_user_print(struct pt_regs *regs, int verbose,
int levels, struct unwind_context *uwcontext,
struct uretprobe_instance *ri, int uregs_valid)
{
struct unwind_frame_info *info = &uwcontext->info;
arch_unw_init_frame_info(info, regs, ! uregs_valid);
while (levels) {
int ret = unwind(uwcontext, 1);
#ifdef STAPCONF_UPROBE_GET_PC
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_valid_pc_addr(UNW_PC(info), current)) {
_stp_print_addr(UNW_PC(info), verbose, current);
levels--;
continue;
}
/* If an error happened or the PC becomes invalid, then
* we are done, _stp_stack_print_fallback is only for
* kernel space. */
return;
}
}
static void __stp_stack_print(struct pt_regs *regs, int verbose, int levels,
struct task_struct *tsk,
struct uretprobe_instance *ri, int uregs_valid)
{
#ifdef STP_USE_DWARF_UNWINDER
int start_levels = levels;
// FIXME: large stack allocation
struct unwind_frame_info info;
int sanitize = tsk && ! uregs_valid;
arch_unw_init_frame_info(&info, regs, sanitize);
while (levels && (tsk || !arch_unw_user_mode(&info))) {
int ret = unwind(&info, tsk);
#ifdef STAPCONF_UPROBE_GET_PC
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_print_addr(UNW_PC(&info), verbose, 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(REG_SP(regs), verbose, levels);
#endif
}
static unsigned long _stp_stack_unwind_one_user(struct context *c, unsigned depth)
{
struct pt_regs *regs = NULL;
int uregs_valid = 0;
struct uretprobe_instance *ri = NULL;
struct unwind_frame_info *info = NULL;
int ret;
#ifdef STAPCONF_UPROBE_GET_PC
unsigned long maybe_pc;
#endif
if (c->probe_type == stp_probe_type_uretprobe)
ri = c->ips.ri;
#ifdef STAPCONF_UPROBE_GET_PC
else if (c->probe_type == stp_probe_type_uprobe)
ri = GET_PC_URETPROBE_NONE;
#endif
/* XXX: The computation that gives this is cached, so calling
* _stp_get_uregs multiple times is okay... probably. */
regs = _stp_get_uregs(c);
uregs_valid = c->full_uregs_p;
if (! current->mm || ! regs)
return 0; // no user backtrace at this probe point
if (depth == 0) { /* Start by fetching the current PC. */
dbug_unwind(1, "STARTING user unwind\n");
#ifdef STAPCONF_UPROBE_GET_PC
if (c->probe_type == stp_probe_type_uretprobe && ri) {
return ri->ret_addr;
} else {
return REG_IP(regs);
}
#else
return REG_IP(regs);
#endif
}
#ifdef STP_USE_DWARF_UNWINDER
info = &c->uwcontext_user.info;
dbug_unwind(1, "CONTINUING user unwind to depth %d\n", depth);
if (depth == 1) { /* need to clear uregs & set up uwcontext->info */
if (c->uregs == &c->uwcontext_user.info.regs) {
dbug_unwind(1, "clearing uregs\n");
/* Unwinder needs the reg state, clear uregs ref. */
c->uregs = NULL;
c->full_uregs_p = 0;
}
arch_unw_init_frame_info(info, regs, 0);
}
ret = unwind(&c->uwcontext_user, 1);
#ifdef STAPCONF_UPROBE_GET_PC
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=%llx SP=%llx\n", ret,
(unsigned long long) UNW_PC(info), (unsigned long long) UNW_SP(info));
/* check if unwind hit an error */
if (ret || ! _stp_valid_pc_addr(UNW_PC(info), current)) {
return 0;
}
return UNW_PC(info);
#else
/* User stack traces only supported for arches with dwarf unwinder. */
return 0;
#endif
}