selftests/bpf: Add read-only map values propagation tests

// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

struct bss {

	unsigned did_run;

	unsigned iters;

	unsigned sum;

};

struct rdonly_map_subtest {

	const char *subtest_name;

	const char *prog_name;

	unsigned exp_iters;

	unsigned exp_sum;

};

void test_rdonly_maps(void)

{

	const char *prog_name_skip_loop = "raw_tracepoint/sys_enter:skip_loop";

	const char *prog_name_part_loop = "raw_tracepoint/sys_enter:part_loop";

	const char *prog_name_full_loop = "raw_tracepoint/sys_enter:full_loop";

	const char *file = "test_rdonly_maps.o";

	struct rdonly_map_subtest subtests[] = {

		{ "skip loop", prog_name_skip_loop, 0, 0 },

		{ "part loop", prog_name_part_loop, 3, 2 + 3 + 4 },

		{ "full loop", prog_name_full_loop, 4, 2 + 3 + 4 + 5 },

	};

	int i, err, zero = 0, duration = 0;

	struct bpf_link *link = NULL;

	struct bpf_program *prog;

	struct bpf_map *bss_map;

	struct bpf_object *obj;

	struct bss bss;

	obj = bpf_object__open_file(file, NULL);

	if (CHECK(IS_ERR(obj), "obj_open", "err %ld\n", PTR_ERR(obj)))

		return;

	bpf_object__for_each_program(prog, obj) {

		bpf_program__set_raw_tracepoint(prog);

	}

	err = bpf_object__load(obj);

	if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))

		goto cleanup;

	bss_map = bpf_object__find_map_by_name(obj, "test_rdo.bss");

	if (CHECK(!bss_map, "find_bss_map", "failed\n"))

		goto cleanup;

	for (i = 0; i < ARRAY_SIZE(subtests); i++) {

		const struct rdonly_map_subtest *t = &subtests[i];

		if (!test__start_subtest(t->subtest_name))

			continue;

		prog = bpf_object__find_program_by_title(obj, t->prog_name);

		if (CHECK(!prog, "find_prog", "prog '%s' not found\n",

			  t->prog_name))

			goto cleanup;

		memset(&bss, 0, sizeof(bss));

		err = bpf_map_update_elem(bpf_map__fd(bss_map), &zero, &bss, 0);

		if (CHECK(err, "set_bss", "failed to set bss data: %d\n", err))

			goto cleanup;

		link = bpf_program__attach_raw_tracepoint(prog, "sys_enter");

		if (CHECK(IS_ERR(link), "attach_prog", "prog '%s', err %ld\n",

			  t->prog_name, PTR_ERR(link))) {

			link = NULL;

			goto cleanup;

		}

		/* trigger probe */

		usleep(1);

		bpf_link__destroy(link);

		link = NULL;

		err = bpf_map_lookup_elem(bpf_map__fd(bss_map), &zero, &bss);

		if (CHECK(err, "get_bss", "failed to get bss data: %d\n", err))

			goto cleanup;

		if (CHECK(bss.did_run == 0, "check_run",

			  "prog '%s' didn't run?\n", t->prog_name))

			goto cleanup;

		if (CHECK(bss.iters != t->exp_iters, "check_iters",

			  "prog '%s' iters: %d, expected: %d\n",

			  t->prog_name, bss.iters, t->exp_iters))

			goto cleanup;

		if (CHECK(bss.sum != t->exp_sum, "check_sum",

			  "prog '%s' sum: %d, expected: %d\n",

			  t->prog_name, bss.sum, t->exp_sum))

			goto cleanup;

	}

cleanup:

	bpf_link__destroy(link);

	bpf_object__close(obj);

}

// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2019 Facebook

#include <linux/ptrace.h>

#include <linux/bpf.h>

#include "bpf_helpers.h"

static volatile const struct {

	unsigned a[4];

	/*

	 * if the struct's size is multiple of 16, compiler will put it into

	 * .rodata.cst16 section, which is not recognized by libbpf; work

	 * around this by ensuring we don't have 16-aligned struct

	 */

	char _y;

} rdonly_values = { .a = {2, 3, 4, 5} };

static volatile struct {

	unsigned did_run;

	unsigned iters;

	unsigned sum;

} res;

SEC("raw_tracepoint/sys_enter:skip_loop")

int skip_loop(struct pt_regs *ctx)

{

	/* prevent compiler to optimize everything out */

	unsigned * volatile p = (void *)&rdonly_values.a;

	unsigned iters = 0, sum = 0;

	/* we should never enter this loop */

	while (*p & 1) {

		iters++;

		sum += *p;

		p++;

	}

	res.did_run = 1;

	res.iters = iters;

	res.sum = sum;

	return 0;

}

SEC("raw_tracepoint/sys_enter:part_loop")

int part_loop(struct pt_regs *ctx)

{

	/* prevent compiler to optimize everything out */

	unsigned * volatile p = (void *)&rdonly_values.a;

	unsigned iters = 0, sum = 0;

	/* validate verifier can derive loop termination */

	while (*p < 5) {

		iters++;

		sum += *p;

		p++;

	}

	res.did_run = 1;

	res.iters = iters;

	res.sum = sum;

	return 0;

}

SEC("raw_tracepoint/sys_enter:full_loop")

int full_loop(struct pt_regs *ctx)

{

	/* prevent compiler to optimize everything out */

	unsigned * volatile p = (void *)&rdonly_values.a;

	int i = sizeof(rdonly_values.a) / sizeof(rdonly_values.a[0]);

	unsigned iters = 0, sum = 0;

	/* validate verifier can allow full loop as well */

	while (i > 0 ) {

		iters++;

		sum += *p;

		p++;

		i--;

	}

	res.did_run = 1;

	res.iters = iters;

	res.sum = sum;

	return 0;

}

char _license[] SEC("license") = "GPL";