static unsigned long _stp_stack_unwind_one_kernel(struct context *c, unsigned depth)
{
struct pt_regs *regs = NULL;
struct unwind_frame_info *info = NULL;
int ret;
if (depth == 0) { /* Start by fetching the current PC. */
dbug_unwind(1, "STARTING kernel unwind\n");
if (! c->kregs) {
/* Even the current PC is unknown; so we have
* absolutely no data at any depth.
*
* Note that unlike _stp_stack_kernel_print(),
* we can't fall back to calling dump_trace()
* to obtain the backtrace -- since that
* returns a string, which we would have to
* tokenize. Callers that want to use the
* dump_trace() fallback should call
* _stp_stack_kernel_print() and do their own
* tokenization of the result. */
#if defined (__i386__) || defined (__x86_64__)
arch_unw_init_frame_info(&c->uwcontext_kernel.info, NULL, 0);
return UNW_PC(&c->uwcontext_kernel.info);
#else
return 0;
#endif
} else if (c->probe_type == stp_probe_type_kretprobe
&& c->ips.krp.pi) {
return (unsigned long)_stp_ret_addr_r(c->ips.krp.pi);
} else {
return REG_IP(c->kregs);
}
}
#ifdef STP_USE_DWARF_UNWINDER
/* Otherwise, use the DWARF unwinder to unwind one step. */
regs = c->kregs;
info = &c->uwcontext_kernel.info;
dbug_unwind(1, "CONTINUING kernel unwind to depth %d\n", depth);
if (depth == 1) {
/* First step of actual DWARF unwind;
need to clear uregs& set up uwcontext->info. */
if (c->uregs == &c->uwcontext_kernel.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_kernel, 0);
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), NULL)) {
return 0;
}
return UNW_PC(info);
#else
return 0;
#endif
}
static void _stp_stack_kernel_print(struct context *c, int sym_flags)
{
struct pt_regs *regs = NULL;
if (! c->kregs) {
/* For the kernel we can use an inexact fallback.
When compiled with frame pointers we can do
a pretty good guess at the stack value,
otherwise let dump_stack guess it
(and skip some framework frames). */
#if defined(STAPCONF_KERNEL_STACKTRACE) || defined(STAPCONF_KERNEL_STACKTRACE_NO_BP)
unsigned long sp;
int skip;
#ifdef CONFIG_FRAME_POINTER
sp = *(unsigned long *) __builtin_frame_address (0);
skip = 1; /* Skip just this frame. */
#else
sp = 0;
skip = 5; /* yes, that many framework frames. */
#endif
_stp_stack_print_fallback(sp, sym_flags,
MAXBACKTRACE, skip);
#else
if (sym_flags & _STP_SYM_SYMBOL)
_stp_printf("<no kernel backtrace at %s>\n",
c->probe_point);
else
_stp_print("\n");
#endif
return;
} else {
regs = c->kregs;
}
/* print the current address */
if (c->probe_type == _STP_PROBE_HANDLER_KRETPROBE && c->ips.krp.pi) {
if ((sym_flags & _STP_SYM_FULL) == _STP_SYM_FULL) {
_stp_print("Returning from: ");
_stp_print_addr((unsigned long)_stp_probe_addr_r(c->ips.krp.pi),
sym_flags, NULL);
_stp_print("Returning to : ");
}
_stp_print_addr((unsigned long)_stp_ret_addr_r(c->ips.krp.pi),
sym_flags, NULL);
} else {
_stp_print_addr(REG_IP(regs), sym_flags, NULL);
}
/* print rest of stack... */
#ifdef STP_USE_DWARF_UNWINDER
if (c->uregs == &c->uwcontext.info.regs) {
/* Unwinder needs the reg state, clear uregs ref. */
c->uregs = NULL;
c->probe_flags &= ~_STP_PROBE_STATE_FULL_UREGS;
}
__stp_dwarf_stack_kernel_print(regs, sym_flags, MAXBACKTRACE,
&c->uwcontext);
#else
/* Arch specific fallback for kernel backtraces. */
__stp_stack_print(regs, sym_flags, MAXBACKTRACE);
#endif
}