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// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/zalloc.h>
#include <inttypes.h>
#include <limits.h>
#include <unistd.h>
#include "tests.h"
#include "debug.h"
#include "machine.h"
#include "event.h"
#include "../util/unwind.h"
#include "perf_regs.h"
#include "map.h"
#include "symbol.h"
#include "thread.h"
#include "callchain.h"
#include "util/synthetic-events.h"
/* For bsearch. We try to unwind functions in shared object. */
#include <stdlib.h>
/*
* The test will assert frames are on the stack but tail call optimizations lose
* the frame of the caller. Clang can disable this optimization on a called
* function but GCC currently (11/2020) lacks this attribute. The barrier is
* used to inhibit tail calls in these cases.
*/
#ifdef __has_attribute
#if __has_attribute(disable_tail_calls)
#define NO_TAIL_CALL_ATTRIBUTE __attribute__((disable_tail_calls))
#define NO_TAIL_CALL_BARRIER
#endif
#endif
#ifndef NO_TAIL_CALL_ATTRIBUTE
#define NO_TAIL_CALL_ATTRIBUTE
#define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory");
#endif
static int mmap_handler(struct perf_tool *tool __maybe_unused,
union perf_event *event,
struct perf_sample *sample,
struct machine *machine)
{
return machine__process_mmap2_event(machine, event, sample);
}
static int init_live_machine(struct machine *machine)
{
union perf_event event;
pid_t pid = getpid();
memset(&event, 0, sizeof(event));
return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
mmap_handler, machine, true);
}
/*
* We need to keep these functions global, despite the
* fact that they are used only locally in this object,
* in order to keep them around even if the binary is
* stripped. If they are gone, the unwind check for
* symbol fails.
*/
int test_dwarf_unwind__thread(struct thread *thread);
int test_dwarf_unwind__compare(void *p1, void *p2);
int test_dwarf_unwind__krava_3(struct thread *thread);
int test_dwarf_unwind__krava_2(struct thread *thread);
int test_dwarf_unwind__krava_1(struct thread *thread);
#define MAX_STACK 8
static int unwind_entry(struct unwind_entry *entry, void *arg)
{
unsigned long *cnt = (unsigned long *) arg;
char *symbol = entry->ms.sym ? entry->ms.sym->name : NULL;
static const char *funcs[MAX_STACK] = {
"test__arch_unwind_sample",
"test_dwarf_unwind__thread",
"test_dwarf_unwind__compare",
"bsearch",
"test_dwarf_unwind__krava_3",
"test_dwarf_unwind__krava_2",
"test_dwarf_unwind__krava_1",
"test__dwarf_unwind"
};
/*
* The funcs[MAX_STACK] array index, based on the
* callchain order setup.
*/
int idx = callchain_param.order == ORDER_CALLER ?
MAX_STACK - *cnt - 1 : *cnt;
if (*cnt >= MAX_STACK) {
pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);
return -1;
}
if (!symbol) {
pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",
entry->ip);
return -1;
}
(*cnt)++;
pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n",
symbol, entry->ip, funcs[idx]);
return strcmp((const char *) symbol, funcs[idx]);
}
NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__thread(struct thread *thread)
{
struct perf_sample sample;
unsigned long cnt = 0;
int err = -1;
memset(&sample, 0, sizeof(sample));
if (test__arch_unwind_sample(&sample, thread)) {
pr_debug("failed to get unwind sample\n");
goto out;
}
err = unwind__get_entries(unwind_entry, &cnt, thread,
&sample, MAX_STACK);
if (err)
pr_debug("unwind failed\n");
else if (cnt != MAX_STACK) {
pr_debug("got wrong number of stack entries %lu != %d\n",
cnt, MAX_STACK);
err = -1;
}
out:
zfree(&sample.user_stack.data);
zfree(&sample.user_regs.regs);
return err;
}
static int global_unwind_retval = -INT_MAX;
NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__compare(void *p1, void *p2)
{
/* Any possible value should be 'thread' */
struct thread *thread = *(struct thread **)p1;
if (global_unwind_retval == -INT_MAX) {
/* Call unwinder twice for both callchain orders. */
callchain_param.order = ORDER_CALLER;
global_unwind_retval = test_dwarf_unwind__thread(thread);
if (!global_unwind_retval) {
callchain_param.order = ORDER_CALLEE;
global_unwind_retval = test_dwarf_unwind__thread(thread);
}
}
return p1 - p2;
}
NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_3(struct thread *thread)
{
struct thread *array[2] = {thread, thread};
void *fp = &bsearch;
/*
* make _bsearch a volatile function pointer to
* prevent potential optimization, which may expand
* bsearch and call compare directly from this function,
* instead of libc shared object.
*/
void *(*volatile _bsearch)(void *, void *, size_t,
size_t, int (*)(void *, void *));
_bsearch = fp;
_bsearch(array, &thread, 2, sizeof(struct thread **),
test_dwarf_unwind__compare);
return global_unwind_retval;
}
NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_2(struct thread *thread)
{
int ret;
ret = test_dwarf_unwind__krava_3(thread);
NO_TAIL_CALL_BARRIER;
return ret;
}
NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_1(struct thread *thread)
{
int ret;
ret = test_dwarf_unwind__krava_2(thread);
NO_TAIL_CALL_BARRIER;
return ret;
}
int test__dwarf_unwind(struct test *test __maybe_unused, int subtest __maybe_unused)
{
struct machine *machine;
struct thread *thread;
int err = -1;
machine = machine__new_host();
if (!machine) {
pr_err("Could not get machine\n");
return -1;
}
if (machine__create_kernel_maps(machine)) {
pr_err("Failed to create kernel maps\n");
return -1;
}
callchain_param.record_mode = CALLCHAIN_DWARF;
dwarf_callchain_users = true;
if (init_live_machine(machine)) {
pr_err("Could not init machine\n");
goto out;
}
if (verbose > 1)
machine__fprintf(machine, stderr);
thread = machine__find_thread(machine, getpid(), getpid());
if (!thread) {
pr_err("Could not get thread\n");
goto out;
}
err = test_dwarf_unwind__krava_1(thread);
thread__put(thread);
out:
machine__delete_threads(machine);
machine__delete(machine);
return err;
}
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