Quelle  bench_trigger.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Facebook */
#define _GNU_SOURCE
#include <argp.h>
#include <unistd.h>
#include <stdint.h>
#include "bpf_util.h"
#include "bench.h"
#include "trigger_bench.skel.h"
#include "trace_helpers.h"

#define MAX_TRIG_BATCH_ITERS 1000

static struct {
 __u32 batch_iters;
} args = {
 .batch_iters = 100,
};

enum {
 ARG_TRIG_BATCH_ITERS = 7000,
};

static const struct argp_option opts[] = {
 { "trig-batch-iters", ARG_TRIG_BATCH_ITERS, "BATCH_ITER_CNT", 0,
  "Number of in-kernel iterations per one driver test run"},
 {},
};

static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
 long ret;

 switch (key) {
 case ARG_TRIG_BATCH_ITERS:
  ret = strtol(arg, NULL, 10);
  if (ret < 1 || ret > MAX_TRIG_BATCH_ITERS) {
   fprintf(stderr, "invalid --trig-batch-iters value (should be between %d and %d)\n",
    1, MAX_TRIG_BATCH_ITERS);
   argp_usage(state);
  }
  args.batch_iters = ret;
  break;
 default:
  return ARGP_ERR_UNKNOWN;
 }

 return 0;
}

const struct argp bench_trigger_batch_argp = {
 .options = opts,
 .parser = parse_arg,
};

/* adjust slot shift in inc_hits() if changing */
#define MAX_BUCKETS 256

#pragma GCC diagnostic ignored "-Wattributes"

/* BPF triggering benchmarks */
static struct trigger_ctx {
 struct trigger_bench *skel;
 bool usermode_counters;
 int driver_prog_fd;
} ctx;

static struct counter base_hits[MAX_BUCKETS];

static __always_inline void inc_counter(struct counter *counters)
{
 static __thread int tid = 0;
 unsigned slot;

 if (unlikely(tid == 0))
  tid = sys_gettid();

 /* multiplicative hashing, it's fast */
 slot = 2654435769U * tid;
 slot >>= 24;

 atomic_inc(&base_hits[slot].value); /* use highest byte as an index */
}

static long sum_and_reset_counters(struct counter *counters)
{
 int i;
 long sum = 0;

 for (i = 0; i < MAX_BUCKETS; i++)
  sum += atomic_swap(&counters[i].value, 0);
 return sum;
}

static void trigger_validate(void)
{
 if (env.consumer_cnt != 0) {
  fprintf(stderr, "benchmark doesn't support consumer!\n");
  exit(1);
 }
}

static void *trigger_producer(void *input)
{
 if (ctx.usermode_counters) {
  while (true) {
   (void)syscall(__NR_getpgid);
   inc_counter(base_hits);
  }
 } else {
  while (true)
   (void)syscall(__NR_getpgid);
 }
 return NULL;
}

static void *trigger_producer_batch(void *input)
{
 int fd = ctx.driver_prog_fd ?: bpf_program__fd(ctx.skel->progs.trigger_driver);

 while (true)
  bpf_prog_test_run_opts(fd, NULL);

 return NULL;
}

static void trigger_measure(struct bench_res *res)
{
 if (ctx.usermode_counters)
  res->hits = sum_and_reset_counters(base_hits);
 else
  res->hits = sum_and_reset_counters(ctx.skel->bss->hits);
}

static void setup_ctx(void)
{
 setup_libbpf();

 ctx.skel = trigger_bench__open();
 if (!ctx.skel) {
  fprintf(stderr, "failed to open skeleton\n");
  exit(1);
 }

 /* default "driver" BPF program */
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver, true);

 ctx.skel->rodata->batch_iters = args.batch_iters;
}

static void load_ctx(void)
{
 int err;

 err = trigger_bench__load(ctx.skel);
 if (err) {
  fprintf(stderr, "failed to open skeleton\n");
  exit(1);
 }
}

static void attach_bpf(struct bpf_program *prog)
{
 struct bpf_link *link;

 link = bpf_program__attach(prog);
 if (!link) {
  fprintf(stderr, "failed to attach program!\n");
  exit(1);
 }
}

static void trigger_syscall_count_setup(void)
{
 ctx.usermode_counters = true;
}

/* Batched, staying mostly in-kernel triggering setups */
static void trigger_kernel_count_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver, false);
 bpf_program__set_autoload(ctx.skel->progs.trigger_count, true);
 load_ctx();
 /* override driver program */
 ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_count);
}

static void trigger_kprobe_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_kprobe, true);
 load_ctx();
 attach_bpf(ctx.skel->progs.bench_trigger_kprobe);
}

static void trigger_kretprobe_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_kretprobe, true);
 load_ctx();
 attach_bpf(ctx.skel->progs.bench_trigger_kretprobe);
}

static void trigger_kprobe_multi_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_kprobe_multi, true);
 load_ctx();
 attach_bpf(ctx.skel->progs.bench_trigger_kprobe_multi);
}

static void trigger_kretprobe_multi_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_kretprobe_multi, true);
 load_ctx();
 attach_bpf(ctx.skel->progs.bench_trigger_kretprobe_multi);
}

static void trigger_fentry_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_fentry, true);
 load_ctx();
 attach_bpf(ctx.skel->progs.bench_trigger_fentry);
}

static void trigger_fexit_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_fexit, true);
 load_ctx();
 attach_bpf(ctx.skel->progs.bench_trigger_fexit);
}

static void trigger_fmodret_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver, false);
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver_kfunc, true);
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_fmodret, true);
 load_ctx();
 /* override driver program */
 ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_driver_kfunc);
 attach_bpf(ctx.skel->progs.bench_trigger_fmodret);
}

static void trigger_tp_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver, false);
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver_kfunc, true);
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_tp, true);
 load_ctx();
 /* override driver program */
 ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_driver_kfunc);
 attach_bpf(ctx.skel->progs.bench_trigger_tp);
}

static void trigger_rawtp_setup(void)
{
 setup_ctx();
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver, false);
 bpf_program__set_autoload(ctx.skel->progs.trigger_driver_kfunc, true);
 bpf_program__set_autoload(ctx.skel->progs.bench_trigger_rawtp, true);
 load_ctx();
 /* override driver program */
 ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_driver_kfunc);
 attach_bpf(ctx.skel->progs.bench_trigger_rawtp);
}

/* make sure call is not inlined and not avoided by compiler, so __weak and
 * inline asm volatile in the body of the function
 *
 * There is a performance difference between uprobing at nop location vs other
 * instructions. So use two different targets, one of which starts with nop
 * and another doesn't.
 *
 * GCC doesn't generate stack setup preamble for these functions due to them
 * having no input arguments and doing nothing in the body.
 */
__nocf_check __weak void uprobe_target_nop(void)
{
 asm volatile ("nop");
}

__weak void opaque_noop_func(void)
{
}

__nocf_check __weak int uprobe_target_push(void)
{
 /* overhead of function call is negligible compared to uprobe
 * triggering, so this shouldn't affect benchmark results much
 */
 opaque_noop_func();
 return 1;
}

__nocf_check __weak void uprobe_target_ret(void)
{
 asm volatile ("");
}

static void *uprobe_producer_count(void *input)
{
 while (true) {
  uprobe_target_nop();
  inc_counter(base_hits);
 }
 return NULL;
}

static void *uprobe_producer_nop(void *input)
{
 while (true)
  uprobe_target_nop();
 return NULL;
}

static void *uprobe_producer_push(void *input)
{
 while (true)
  uprobe_target_push();
 return NULL;
}

static void *uprobe_producer_ret(void *input)
{
 while (true)
  uprobe_target_ret();
 return NULL;
}

#ifdef __x86_64__
__nocf_check __weak void uprobe_target_nop5(void)
{
 asm volatile (".byte 0x0f, 0x1f, 0x44, 0x00, 0x00");
}

static void *uprobe_producer_nop5(void *input)
{
 while (true)
  uprobe_target_nop5();
 return NULL;
}
#endif

static void usetup(bool use_retprobe, bool use_multi, void *target_addr)
{
 size_t uprobe_offset;
 struct bpf_link *link;
 int err;

 setup_libbpf();

 ctx.skel = trigger_bench__open();
 if (!ctx.skel) {
  fprintf(stderr, "failed to open skeleton\n");
  exit(1);
 }

 if (use_multi)
  bpf_program__set_autoload(ctx.skel->progs.bench_trigger_uprobe_multi, true);
 else
  bpf_program__set_autoload(ctx.skel->progs.bench_trigger_uprobe, true);

 err = trigger_bench__load(ctx.skel);
 if (err) {
  fprintf(stderr, "failed to load skeleton\n");
  exit(1);
 }

 uprobe_offset = get_uprobe_offset(target_addr);
 if (use_multi) {
  LIBBPF_OPTS(bpf_uprobe_multi_opts, opts,
   .retprobe = use_retprobe,
   .cnt = 1,
   .offsets = &uprobe_offset,
  );
  link = bpf_program__attach_uprobe_multi(
   ctx.skel->progs.bench_trigger_uprobe_multi,
   -1 /* all PIDs */, "/proc/self/exe", NULL, &opts);
  ctx.skel->links.bench_trigger_uprobe_multi = link;
 } else {
  link = bpf_program__attach_uprobe(ctx.skel->progs.bench_trigger_uprobe,
        use_retprobe,
        -1 /* all PIDs */,
        "/proc/self/exe",
        uprobe_offset);
  ctx.skel->links.bench_trigger_uprobe = link;
 }
 if (!link) {
  fprintf(stderr, "failed to attach %s!\n", use_multi ? "multi-uprobe" : "uprobe");
  exit(1);
 }
}

static void usermode_count_setup(void)
{
 ctx.usermode_counters = true;
}

static void uprobe_nop_setup(void)
{
 usetup(false, false /* !use_multi */, &uprobe_target_nop);
}

static void uretprobe_nop_setup(void)
{
 usetup(true, false /* !use_multi */, &uprobe_target_nop);
}

static void uprobe_push_setup(void)
{
 usetup(false, false /* !use_multi */, &uprobe_target_push);
}

static void uretprobe_push_setup(void)
{
 usetup(true, false /* !use_multi */, &uprobe_target_push);
}

static void uprobe_ret_setup(void)
{
 usetup(false, false /* !use_multi */, &uprobe_target_ret);
}

static void uretprobe_ret_setup(void)
{
 usetup(true, false /* !use_multi */, &uprobe_target_ret);
}

static void uprobe_multi_nop_setup(void)
{
 usetup(false, true /* use_multi */, &uprobe_target_nop);
}

static void uretprobe_multi_nop_setup(void)
{
 usetup(true, true /* use_multi */, &uprobe_target_nop);
}

static void uprobe_multi_push_setup(void)
{
 usetup(false, true /* use_multi */, &uprobe_target_push);
}

static void uretprobe_multi_push_setup(void)
{
 usetup(true, true /* use_multi */, &uprobe_target_push);
}

static void uprobe_multi_ret_setup(void)
{
 usetup(false, true /* use_multi */, &uprobe_target_ret);
}

static void uretprobe_multi_ret_setup(void)
{
 usetup(true, true /* use_multi */, &uprobe_target_ret);
}

#ifdef __x86_64__
static void uprobe_nop5_setup(void)
{
 usetup(false, false /* !use_multi */, &uprobe_target_nop5);
}

static void uretprobe_nop5_setup(void)
{
 usetup(true, false /* !use_multi */, &uprobe_target_nop5);
}

static void uprobe_multi_nop5_setup(void)
{
 usetup(false, true /* use_multi */, &uprobe_target_nop5);
}

static void uretprobe_multi_nop5_setup(void)
{
 usetup(true, true /* use_multi */, &uprobe_target_nop5);
}
#endif

const struct bench bench_trig_syscall_count = {
 .name = "trig-syscall-count",
 .validate = trigger_validate,
 .setup = trigger_syscall_count_setup,
 .producer_thread = trigger_producer,
 .measure = trigger_measure,
 .report_progress = hits_drops_report_progress,
 .report_final = hits_drops_report_final,
};

/* batched (staying mostly in kernel) kprobe/fentry benchmarks */
#define BENCH_TRIG_KERNEL(KIND, NAME)     \
const struct bench bench_trig_##KIND = {    \
 .name = "trig-" NAME,      \
 .setup = trigger_##KIND##_setup,    \
 .producer_thread = trigger_producer_batch,   \
 .measure = trigger_measure,     \
 .report_progress = hits_drops_report_progress,   \
 .report_final = hits_drops_report_final,   \
 .argp = &bench_trigger_batch_argp,    \
}

BENCH_TRIG_KERNEL(kernel_count, "kernel-count");
BENCH_TRIG_KERNEL(kprobe, "kprobe");
BENCH_TRIG_KERNEL(kretprobe, "kretprobe");
BENCH_TRIG_KERNEL(kprobe_multi, "kprobe-multi");
BENCH_TRIG_KERNEL(kretprobe_multi, "kretprobe-multi");
BENCH_TRIG_KERNEL(fentry, "fentry");
BENCH_TRIG_KERNEL(fexit, "fexit");
BENCH_TRIG_KERNEL(fmodret, "fmodret");
BENCH_TRIG_KERNEL(tp, "tp");
BENCH_TRIG_KERNEL(rawtp, "rawtp");

/* uprobe benchmarks */
#define BENCH_TRIG_USERMODE(KIND, PRODUCER, NAME)   \
const struct bench bench_trig_##KIND = {    \
 .name = "trig-" NAME,      \
 .validate = trigger_validate,     \
 .setup = KIND##_setup,      \
 .producer_thread = uprobe_producer_##PRODUCER,   \
 .measure = trigger_measure,     \
 .report_progress = hits_drops_report_progress,   \
 .report_final = hits_drops_report_final,   \
}

BENCH_TRIG_USERMODE(usermode_count, count, "usermode-count");
BENCH_TRIG_USERMODE(uprobe_nop, nop, "uprobe-nop");
BENCH_TRIG_USERMODE(uprobe_push, push, "uprobe-push");
BENCH_TRIG_USERMODE(uprobe_ret, ret, "uprobe-ret");
BENCH_TRIG_USERMODE(uretprobe_nop, nop, "uretprobe-nop");
BENCH_TRIG_USERMODE(uretprobe_push, push, "uretprobe-push");
BENCH_TRIG_USERMODE(uretprobe_ret, ret, "uretprobe-ret");
BENCH_TRIG_USERMODE(uprobe_multi_nop, nop, "uprobe-multi-nop");
BENCH_TRIG_USERMODE(uprobe_multi_push, push, "uprobe-multi-push");
BENCH_TRIG_USERMODE(uprobe_multi_ret, ret, "uprobe-multi-ret");
BENCH_TRIG_USERMODE(uretprobe_multi_nop, nop, "uretprobe-multi-nop");
BENCH_TRIG_USERMODE(uretprobe_multi_push, push, "uretprobe-multi-push");
BENCH_TRIG_USERMODE(uretprobe_multi_ret, ret, "uretprobe-multi-ret");
#ifdef __x86_64__
BENCH_TRIG_USERMODE(uprobe_nop5, nop5, "uprobe-nop5");
BENCH_TRIG_USERMODE(uretprobe_nop5, nop5, "uretprobe-nop5");
BENCH_TRIG_USERMODE(uprobe_multi_nop5, nop5, "uprobe-multi-nop5");
BENCH_TRIG_USERMODE(uretprobe_multi_nop5, nop5, "uretprobe-multi-nop5");
#endif