wasm-bpf/examples/opensnoop/trace_helpers.c

/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
// Copyright (c) 2020 Wenbo Zhang
//
// Based on ksyms improvements from Andrii Nakryiko, add more helpers.
// 28-Feb-2020   Wenbo Zhang   Created this.
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <ctype.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <time.h>
#include <limits.h>
#include <stdbool.h>
#include "trace_helpers.h"
#include "libbpf-wasm.h"

#define min(x, y) ({				\
	typeof(x) _min1 = (x);			\
	typeof(y) _min2 = (y);			\
	(void) (&_min1 == &_min2);		\
	_min1 < _min2 ? _min1 : _min2; })

#define DISK_NAME_LEN	32

#define MINORBITS	20
#define MINORMASK	((1U << MINORBITS) - 1)

#define MKDEV(ma, mi)	(((ma) << MINORBITS) | (mi))

static void print_stars(unsigned int val, unsigned int val_max, int width)
{
	int num_stars, num_spaces, i;
	bool need_plus;

	num_stars = min(val, val_max) * width / val_max;
	num_spaces = width - num_stars;
	need_plus = val > val_max;

	for (i = 0; i < num_stars; i++)
		printf("*");
	for (i = 0; i < num_spaces; i++)
		printf(" ");
	if (need_plus)
		printf("+");
}

void print_log2_hist(unsigned int *vals, int vals_size, const char *val_type)
{
	int stars_max = 40, idx_max = -1;
	unsigned int val, val_max = 0;
	unsigned long long low, high;
	int stars, width, i;

	for (i = 0; i < vals_size; i++) {
		val = vals[i];
		if (val > 0)
			idx_max = i;
		if (val > val_max)
			val_max = val;
	}

	if (idx_max < 0)
		return;

	printf("%*s%-*s : count    distribution\n", idx_max <= 32 ? 5 : 15, "",
		idx_max <= 32 ? 19 : 29, val_type);

	if (idx_max <= 32)
		stars = stars_max;
	else
		stars = stars_max / 2;

	for (i = 0; i <= idx_max; i++) {
		low = (1ULL << (i + 1)) >> 1;
		high = (1ULL << (i + 1)) - 1;
		if (low == high)
			low -= 1;
		val = vals[i];
		width = idx_max <= 32 ? 10 : 20;
		printf("%*lld -> %-*lld : %-8d |", width, low, width, high, val);
		print_stars(val, val_max, stars);
		printf("|\n");
	}
}

void print_linear_hist(unsigned int *vals, int vals_size, unsigned int base,
		       unsigned int step, const char *val_type)
{
	int i, stars_max = 40, idx_min = -1, idx_max = -1;
	unsigned int val, val_max = 0;

	for (i = 0; i < vals_size; i++) {
		val = vals[i];
		if (val > 0) {
			idx_max = i;
			if (idx_min < 0)
				idx_min = i;
		}
		if (val > val_max)
			val_max = val;
	}

	if (idx_max < 0)
		return;

	printf("     %-13s : count     distribution\n", val_type);
	for (i = idx_min; i <= idx_max; i++) {
		val = vals[i];
		if (!val)
			continue;
		printf("        %-10d : %-8d |", base + i * step, val);
		print_stars(val, val_max, stars_max);
		printf("|\n");
	}
}

unsigned long long get_ktime_ns(void)
{
	struct timespec ts;

	clock_gettime(CLOCK_MONOTONIC, &ts);
	return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec;
}

bool is_kernel_module(const char *name)
{
	bool found = false;
	char buf[64];
	FILE *f;

	f = fopen("/proc/modules", "r");
	if (!f)
		return false;

	while (fgets(buf, sizeof(buf), f) != NULL) {
		if (sscanf(buf, "%s %*s\n", buf) != 1)
			break;
		if (!strcmp(buf, name)) {
			found = true;
			break;
		}
	}

	fclose(f);
	return found;
}

bool kprobe_exists(const char *name)
{
	char sym_name[256];
	FILE *f;
	int ret;

	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
	if (!f)
		goto slow_path;

	while (true) {
		ret = fscanf(f, "%s%*[^\n]\n", sym_name);
		if (ret == EOF && feof(f))
			break;
		if (ret != 1) {
			fprintf(stderr, "failed to read symbol from available_filter_functions\n");
			break;
		}
		if (!strcmp(name, sym_name)) {
			fclose(f);
			return true;
		}
	}

	fclose(f);
	return false;

slow_path:
	f = fopen("/proc/kallsyms", "r");
	if (!f)
		return false;

	while (true) {
		ret = fscanf(f, "%*x %*c %s%*[^\n]\n", sym_name);
		if (ret == EOF && feof(f))
			break;
		if (ret != 1) {
			fprintf(stderr, "failed to read symbol from kallsyms\n");
			break;
		}
		if (!strcmp(name, sym_name)) {
			fclose(f);
			return true;
		}
	}

	fclose(f);
	return false;
}

bool tracepoint_exists(const char *category, const char *event)
{
	char path[PATH_MAX];

	snprintf(path, sizeof(path), "/sys/kernel/debug/tracing/events/%s/%s/format", category, event);
	if (!access(path, F_OK))
		return true;
	return false;
}

bool module_btf_exists(const char *mod)
{
	char sysfs_mod[80];

	if (mod) {
		snprintf(sysfs_mod, sizeof(sysfs_mod), "/sys/kernel/btf/%s", mod);
		if (!access(sysfs_mod, R_OK))
			return true;
	}
	return false;
}


bool probe_tp_btf(const char *name)
{
	// LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_TRACE_RAW_TP);
	// struct bpf_insn insns[] = {
	// 	{ .code = BPF_ALU64 | BPF_MOV | BPF_K, .dst_reg = BPF_REG_0, .imm = 0 },
	// 	{ .code = BPF_JMP | BPF_EXIT },
	// };
	// int fd, insn_cnt = sizeof(insns) / sizeof(struct bpf_insn);

	// opts.attach_btf_id = libbpf_find_vmlinux_btf_id(name, BPF_TRACE_RAW_TP);
	// fd = bpf_prog_load(BPF_PROG_TYPE_TRACING, NULL, "GPL", insns, insn_cnt, &opts);
	// if (fd >= 0)
	// 	close(fd);
	return false;
}

bool probe_ringbuf()
{
	int map_fd;

	// map_fd = bpf_map_create(BPF_MAP_TYPE_RINGBUF, NULL, 0, 0, getpagesize(), NULL);
	// if (map_fd < 0)
	// 	return false;

	// close(map_fd);
	return false;
}