static int __report_module(struct addr_location *al, u64 ip,
struct unwind_info *ui)
{
Dwfl_Module *mod;
struct dso *dso = NULL;
/*
* Some callers will use al->sym, so we can't just use the
* cheaper thread__find_map() here.
*/
thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
if (al->map)
dso = al->map->dso;
if (!dso)
return 0;
mod = dwfl_addrmodule(ui->dwfl, ip);
if (mod) {
Dwarf_Addr s;
dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
if (s != al->map->start)
mod = 0;
}
if (!mod)
mod = dwfl_report_elf(ui->dwfl, dso->short_name,
(dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start,
false);
return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
}
/*
* The callchain saved by the kernel always includes the link register (LR).
*
* 0: PERF_CONTEXT_USER
* 1: Program counter (Next instruction pointer)
* 2: LR value
* 3: Caller's caller
* 4: ...
*
* The value in LR is only needed when it holds a return address. If the
* return address is on the stack, we should ignore the LR value.
*
* Further, when the return address is in the LR, if a new frame was just
* allocated but the LR was not saved into it, then the LR contains the
* caller, slot 4: contains the caller's caller and the contents of slot 3:
* (chain->ips[3]) is undefined and must be ignored.
*
* Use DWARF debug information to determine if any entries need to be skipped.
*
* Return:
* index: of callchain entry that needs to be ignored (if any)
* -1 if no entry needs to be ignored or in case of errors
*/
int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
{
struct addr_location al;
struct dso *dso = NULL;
int rc;
u64 ip;
u64 skip_slot = -1;
if (!chain || chain->nr < 3)
return skip_slot;
ip = chain->ips[1];
thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
if (al.map)
dso = al.map->dso;
if (!dso) {
pr_debug("%" PRIx64 " dso is NULL\n", ip);
return skip_slot;
}
rc = check_return_addr(dso, al.map->start, ip);
pr_debug("[DSO %s, sym %s, ip 0x%" PRIx64 "] rc %d\n",
dso->long_name, al.sym->name, ip, rc);
if (rc == 0) {
/*
* Return address on stack. Ignore LR value in callchain
*/
skip_slot = 2;
} else if (rc == 2) {
/*
* New frame allocated but return address still in LR.
* Ignore the caller's caller entry in callchain.
*/
skip_slot = 3;
}
return skip_slot;
}
