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linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c
John Fastabend 1fb5ba29ad bpf: Selftest to verify mixing bpf2bpf calls and tailcalls with insn patch 
This adds some extra noise to the tailcall_bpf2bpf4 tests that will cause
verify to patch insns. This then moves around subprog start/end insn
index and poke descriptor insn index to ensure that verify and JIT will
continue to track these correctly.

If done correctly verifier should pass this program same as before and
JIT should emit tail call logic.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210707223848.14580-3-john.fastabend@gmail.com
2021-07-09 12:08:40 +02:00

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// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include <network_helpers.h>
/* test_tailcall_1 checks basic functionality by patching multiple locations
* in a single program for a single tail call slot with nop->jmp, jmp->nop
* and jmp->jmp rewrites. Also checks for nop->nop.
*/
static void test_tailcall_1(void)
{
int err, map_fd, prog_fd, main_fd, i, j;
struct bpf_map *prog_array;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char prog_name[32];
char buff[128] = {};
err = bpf_prog_load("tailcall1.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
&prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != i, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
}
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 3, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
j = bpf_map__def(prog_array)->max_entries - 1 - i;
snprintf(prog_name, sizeof(prog_name), "classifier/%i", j);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
j = bpf_map__def(prog_array)->max_entries - 1 - i;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != j, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
}
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 3, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err >= 0 || errno != ENOENT))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 3, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
}
out:
bpf_object__close(obj);
}
/* test_tailcall_2 checks that patching multiple programs for a single
* tail call slot works. It also jumps through several programs and tests
* the tail call limit counter.
*/
static void test_tailcall_2(void)
{
int err, map_fd, prog_fd, main_fd, i;
struct bpf_map *prog_array;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char prog_name[32];
char buff[128] = {};
err = bpf_prog_load("tailcall2.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
&prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 2, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
i = 2;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 1, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
i = 0;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 3, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
out:
bpf_object__close(obj);
}
/* test_tailcall_3 checks that the count value of the tail call limit
* enforcement matches with expectations.
*/
static void test_tailcall_3(void)
{
int err, map_fd, prog_fd, main_fd, data_fd, i, val;
struct bpf_map *prog_array, *data_map;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char buff[128] = {};
err = bpf_prog_load("tailcall3.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
&prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
prog = bpf_object__find_program_by_title(obj, "classifier/0");
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
i = 0;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 1, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
return;
data_fd = bpf_map__fd(data_map);
if (CHECK_FAIL(map_fd < 0))
return;
i = 0;
err = bpf_map_lookup_elem(data_fd, &i, &val);
CHECK(err || val != 33, "tailcall count", "err %d errno %d count %d\n",
err, errno, val);
i = 0;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
out:
bpf_object__close(obj);
}
/* test_tailcall_4 checks that the kernel properly selects indirect jump
* for the case where the key is not known. Latter is passed via global
* data to select different targets we can compare return value of.
*/
static void test_tailcall_4(void)
{
int err, map_fd, prog_fd, main_fd, data_fd, i;
struct bpf_map *prog_array, *data_map;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
static const int zero = 0;
char buff[128] = {};
char prog_name[32];
err = bpf_prog_load("tailcall4.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
&prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
return;
data_fd = bpf_map__fd(data_map);
if (CHECK_FAIL(map_fd < 0))
return;
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
err = bpf_map_update_elem(data_fd, &zero, &i, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != i, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
}
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
err = bpf_map_update_elem(data_fd, &zero, &i, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 3, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
}
out:
bpf_object__close(obj);
}
/* test_tailcall_5 probes similarly to test_tailcall_4 that the kernel generates
* an indirect jump when the keys are const but different from different branches.
*/
static void test_tailcall_5(void)
{
int err, map_fd, prog_fd, main_fd, data_fd, i, key[] = { 1111, 1234, 5678 };
struct bpf_map *prog_array, *data_map;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
static const int zero = 0;
char buff[128] = {};
char prog_name[32];
err = bpf_prog_load("tailcall5.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
&prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
return;
data_fd = bpf_map__fd(data_map);
if (CHECK_FAIL(map_fd < 0))
return;
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
err = bpf_map_update_elem(data_fd, &zero, &key[i], BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != i, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
}
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
err = bpf_map_update_elem(data_fd, &zero, &key[i], BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 3, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
}
out:
bpf_object__close(obj);
}
/* test_tailcall_bpf2bpf_1 purpose is to make sure that tailcalls are working
* correctly in correlation with BPF subprograms
*/
static void test_tailcall_bpf2bpf_1(void)
{
int err, map_fd, prog_fd, main_fd, i;
struct bpf_map *prog_array;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char prog_name[32];
err = bpf_prog_load("tailcall_bpf2bpf1.o", BPF_PROG_TYPE_SCHED_CLS,
&obj, &prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
/* nop -> jmp */
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
0, &retval, &duration);
CHECK(err || retval != 1, "tailcall",
"err %d errno %d retval %d\n", err, errno, retval);
/* jmp -> nop, call subprog that will do tailcall */
i = 1;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
0, &retval, &duration);
CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
/* make sure that subprog can access ctx and entry prog that
* called this subprog can properly return
*/
i = 0;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
0, &retval, &duration);
CHECK(err || retval != sizeof(pkt_v4) * 2,
"tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
out:
bpf_object__close(obj);
}
/* test_tailcall_bpf2bpf_2 checks that the count value of the tail call limit
* enforcement matches with expectations when tailcall is preceded with
* bpf2bpf call.
*/
static void test_tailcall_bpf2bpf_2(void)
{
int err, map_fd, prog_fd, main_fd, data_fd, i, val;
struct bpf_map *prog_array, *data_map;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char buff[128] = {};
err = bpf_prog_load("tailcall_bpf2bpf2.o", BPF_PROG_TYPE_SCHED_CLS,
&obj, &prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
prog = bpf_object__find_program_by_title(obj, "classifier/0");
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
i = 0;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 1, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
return;
data_fd = bpf_map__fd(data_map);
if (CHECK_FAIL(map_fd < 0))
return;
i = 0;
err = bpf_map_lookup_elem(data_fd, &i, &val);
CHECK(err || val != 33, "tailcall count", "err %d errno %d count %d\n",
err, errno, val);
i = 0;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
&duration, &retval, NULL);
CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
out:
bpf_object__close(obj);
}
/* test_tailcall_bpf2bpf_3 checks that non-trivial amount of stack (up to
* 256 bytes) can be used within bpf subprograms that have the tailcalls
* in them
*/
static void test_tailcall_bpf2bpf_3(void)
{
int err, map_fd, prog_fd, main_fd, i;
struct bpf_map *prog_array;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char prog_name[32];
err = bpf_prog_load("tailcall_bpf2bpf3.o", BPF_PROG_TYPE_SCHED_CLS,
&obj, &prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
&duration, &retval, NULL);
CHECK(err || retval != sizeof(pkt_v4) * 3,
"tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
i = 1;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
&duration, &retval, NULL);
CHECK(err || retval != sizeof(pkt_v4),
"tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
i = 0;
err = bpf_map_delete_elem(map_fd, &i);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
&duration, &retval, NULL);
CHECK(err || retval != sizeof(pkt_v4) * 2,
"tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
out:
bpf_object__close(obj);
}
#include "tailcall_bpf2bpf4.skel.h"
/* test_tailcall_bpf2bpf_4 checks that tailcall counter is correctly preserved
* across tailcalls combined with bpf2bpf calls. for making sure that tailcall
* counter behaves correctly, bpf program will go through following flow:
*
* entry -> entry_subprog -> tailcall0 -> bpf_func0 -> subprog0 ->
* -> tailcall1 -> bpf_func1 -> subprog1 -> tailcall2 -> bpf_func2 ->
* subprog2 [here bump global counter] --------^
*
* We go through first two tailcalls and start counting from the subprog2 where
* the loop begins. At the end of the test make sure that the global counter is
* equal to 31, because tailcall counter includes the first two tailcalls
* whereas global counter is incremented only on loop presented on flow above.
*
* The noise parameter is used to insert bpf_map_update calls into the logic
* to force verifier to patch instructions. This allows us to ensure jump
* logic remains correct with instruction movement.
*/
static void test_tailcall_bpf2bpf_4(bool noise)
{
int err, map_fd, prog_fd, main_fd, data_fd, i;
struct tailcall_bpf2bpf4__bss val;
struct bpf_map *prog_array, *data_map;
struct bpf_program *prog;
struct bpf_object *obj;
__u32 retval, duration;
char prog_name[32];
err = bpf_prog_load("tailcall_bpf2bpf4.o", BPF_PROG_TYPE_SCHED_CLS,
&obj, &prog_fd);
if (CHECK_FAIL(err))
return;
prog = bpf_object__find_program_by_title(obj, "classifier");
if (CHECK_FAIL(!prog))
goto out;
main_fd = bpf_program__fd(prog);
if (CHECK_FAIL(main_fd < 0))
goto out;
prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
if (CHECK_FAIL(!prog_array))
goto out;
map_fd = bpf_map__fd(prog_array);
if (CHECK_FAIL(map_fd < 0))
goto out;
for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK_FAIL(!prog))
goto out;
prog_fd = bpf_program__fd(prog);
if (CHECK_FAIL(prog_fd < 0))
goto out;
err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
}
data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
return;
data_fd = bpf_map__fd(data_map);
if (CHECK_FAIL(map_fd < 0))
return;
i = 0;
val.noise = noise;
val.count = 0;
err = bpf_map_update_elem(data_fd, &i, &val, BPF_ANY);
if (CHECK_FAIL(err))
goto out;
err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
&duration, &retval, NULL);
CHECK(err || retval != sizeof(pkt_v4) * 3, "tailcall", "err %d errno %d retval %d\n",
err, errno, retval);
i = 0;
err = bpf_map_lookup_elem(data_fd, &i, &val);
CHECK(err || val.count != 31, "tailcall count", "err %d errno %d count %d\n",
err, errno, val.count);
out:
bpf_object__close(obj);
}
void test_tailcalls(void)
{
if (test__start_subtest("tailcall_1"))
test_tailcall_1();
if (test__start_subtest("tailcall_2"))
test_tailcall_2();
if (test__start_subtest("tailcall_3"))
test_tailcall_3();
if (test__start_subtest("tailcall_4"))
test_tailcall_4();
if (test__start_subtest("tailcall_5"))
test_tailcall_5();
if (test__start_subtest("tailcall_bpf2bpf_1"))
test_tailcall_bpf2bpf_1();
if (test__start_subtest("tailcall_bpf2bpf_2"))
test_tailcall_bpf2bpf_2();
if (test__start_subtest("tailcall_bpf2bpf_3"))
test_tailcall_bpf2bpf_3();
if (test__start_subtest("tailcall_bpf2bpf_4"))
test_tailcall_bpf2bpf_4(false);
if (test__start_subtest("tailcall_bpf2bpf_5"))
test_tailcall_bpf2bpf_4(true);
}
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