selftests/bpf: add C-level selftests for indirect jumps

Add C-level selftests for indirect jumps to validate LLVM and libbpf
functionality. The tests are intentionally disabled, to be run
locally by developers, but will not make the CI red.

Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Link: https://lore.kernel.org/r/20251105090410.1250500-13-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Anton Protopopov 2025-11-05 09:04:10 +00:00 committed by Alexei Starovoitov
parent ccbdb48ce5
commit ac4d838ce1
3 changed files with 743 additions and 1 deletions

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@ -453,7 +453,9 @@ BPF_CFLAGS = -g -Wall -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \
-I$(abspath $(OUTPUT)/../usr/include) \
-std=gnu11 \
-fno-strict-aliasing \
-Wno-compare-distinct-pointer-types
-Wno-compare-distinct-pointer-types \
-Wno-initializer-overrides \
#
# TODO: enable me -Wsign-compare
CLANG_CFLAGS = $(CLANG_SYS_INCLUDES)

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@ -0,0 +1,292 @@
// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in6.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <sys/syscall.h>
#include <bpf/bpf.h>
#include "bpf_gotox.skel.h"
static void __test_run(struct bpf_program *prog, void *ctx_in, size_t ctx_size_in)
{
LIBBPF_OPTS(bpf_test_run_opts, topts,
.ctx_in = ctx_in,
.ctx_size_in = ctx_size_in,
);
int err, prog_fd;
prog_fd = bpf_program__fd(prog);
err = bpf_prog_test_run_opts(prog_fd, &topts);
ASSERT_OK(err, "test_run_opts err");
}
static void __subtest(struct bpf_gotox *skel, void (*check)(struct bpf_gotox *))
{
if (skel->data->skip)
test__skip();
else
check(skel);
}
static void check_simple(struct bpf_gotox *skel,
struct bpf_program *prog,
__u64 ctx_in,
__u64 expected)
{
skel->bss->ret_user = 0;
__test_run(prog, &ctx_in, sizeof(ctx_in));
if (!ASSERT_EQ(skel->bss->ret_user, expected, "skel->bss->ret_user"))
return;
}
static void check_simple_fentry(struct bpf_gotox *skel,
struct bpf_program *prog,
__u64 ctx_in,
__u64 expected)
{
skel->bss->in_user = ctx_in;
skel->bss->ret_user = 0;
/* trigger */
usleep(1);
if (!ASSERT_EQ(skel->bss->ret_user, expected, "skel->bss->ret_user"))
return;
}
/* validate that for two loads of the same jump table libbpf generates only one map */
static void check_one_map_two_jumps(struct bpf_gotox *skel)
{
struct bpf_prog_info prog_info;
struct bpf_map_info map_info;
__u32 len;
__u32 map_ids[16];
int prog_fd, map_fd;
int ret;
int i;
bool seen = false;
memset(&prog_info, 0, sizeof(prog_info));
prog_info.map_ids = (long)map_ids;
prog_info.nr_map_ids = ARRAY_SIZE(map_ids);
prog_fd = bpf_program__fd(skel->progs.one_map_two_jumps);
if (!ASSERT_GE(prog_fd, 0, "bpf_program__fd(one_map_two_jumps)"))
return;
len = sizeof(prog_info);
ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &len);
if (!ASSERT_OK(ret, "bpf_obj_get_info_by_fd(prog_fd)"))
return;
for (i = 0; i < prog_info.nr_map_ids; i++) {
map_fd = bpf_map_get_fd_by_id(map_ids[i]);
if (!ASSERT_GE(map_fd, 0, "bpf_map_get_fd_by_id"))
return;
len = sizeof(map_info);
memset(&map_info, 0, len);
ret = bpf_obj_get_info_by_fd(map_fd, &map_info, &len);
if (!ASSERT_OK(ret, "bpf_obj_get_info_by_fd(map_fd)")) {
close(map_fd);
return;
}
if (map_info.type == BPF_MAP_TYPE_INSN_ARRAY) {
if (!ASSERT_EQ(seen, false, "more than one INSN_ARRAY map")) {
close(map_fd);
return;
}
seen = true;
}
close(map_fd);
}
ASSERT_EQ(seen, true, "no INSN_ARRAY map");
}
static void check_one_switch(struct bpf_gotox *skel)
{
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.one_switch, in[i], out[i]);
}
static void check_one_switch_non_zero_sec_off(struct bpf_gotox *skel)
{
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.one_switch_non_zero_sec_off, in[i], out[i]);
}
static void check_two_switches(struct bpf_gotox *skel)
{
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {103, 104, 107, 205, 115, 1019, 1019};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.two_switches, in[i], out[i]);
}
static void check_big_jump_table(struct bpf_gotox *skel)
{
__u64 in[] = {0, 11, 27, 31, 22, 45, 99};
__u64 out[] = {2, 3, 4, 5, 19, 19, 19};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.big_jump_table, in[i], out[i]);
}
static void check_one_jump_two_maps(struct bpf_gotox *skel)
{
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {12, 15, 7 , 15, 12, 15, 15};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.one_jump_two_maps, in[i], out[i]);
}
static void check_static_global(struct bpf_gotox *skel)
{
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.use_static_global1, in[i], out[i]);
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.use_static_global2, in[i], out[i]);
}
static void check_nonstatic_global(struct bpf_gotox *skel)
{
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.use_nonstatic_global1, in[i], out[i]);
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple(skel, skel->progs.use_nonstatic_global2, in[i], out[i]);
}
static void check_other_sec(struct bpf_gotox *skel)
{
struct bpf_link *link;
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
link = bpf_program__attach(skel->progs.simple_test_other_sec);
if (!ASSERT_OK_PTR(link, "link"))
return;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple_fentry(skel, skel->progs.simple_test_other_sec, in[i], out[i]);
bpf_link__destroy(link);
}
static void check_static_global_other_sec(struct bpf_gotox *skel)
{
struct bpf_link *link;
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
link = bpf_program__attach(skel->progs.use_static_global_other_sec);
if (!ASSERT_OK_PTR(link, "link"))
return;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple_fentry(skel, skel->progs.use_static_global_other_sec, in[i], out[i]);
bpf_link__destroy(link);
}
static void check_nonstatic_global_other_sec(struct bpf_gotox *skel)
{
struct bpf_link *link;
__u64 in[] = {0, 1, 2, 3, 4, 5, 77};
__u64 out[] = {2, 3, 4, 5, 7, 19, 19};
int i;
link = bpf_program__attach(skel->progs.use_nonstatic_global_other_sec);
if (!ASSERT_OK_PTR(link, "link"))
return;
for (i = 0; i < ARRAY_SIZE(in); i++)
check_simple_fentry(skel, skel->progs.use_nonstatic_global_other_sec, in[i], out[i]);
bpf_link__destroy(link);
}
void test_bpf_gotox(void)
{
struct bpf_gotox *skel;
int ret;
skel = bpf_gotox__open();
if (!ASSERT_NEQ(skel, NULL, "bpf_gotox__open"))
return;
ret = bpf_gotox__load(skel);
if (!ASSERT_OK(ret, "bpf_gotox__load"))
return;
skel->bss->pid = getpid();
if (test__start_subtest("one-switch"))
__subtest(skel, check_one_switch);
if (test__start_subtest("one-switch-non-zero-sec-offset"))
__subtest(skel, check_one_switch_non_zero_sec_off);
if (test__start_subtest("two-switches"))
__subtest(skel, check_two_switches);
if (test__start_subtest("big-jump-table"))
__subtest(skel, check_big_jump_table);
if (test__start_subtest("static-global"))
__subtest(skel, check_static_global);
if (test__start_subtest("nonstatic-global"))
__subtest(skel, check_nonstatic_global);
if (test__start_subtest("other-sec"))
__subtest(skel, check_other_sec);
if (test__start_subtest("static-global-other-sec"))
__subtest(skel, check_static_global_other_sec);
if (test__start_subtest("nonstatic-global-other-sec"))
__subtest(skel, check_nonstatic_global_other_sec);
if (test__start_subtest("one-jump-two-maps"))
__subtest(skel, check_one_jump_two_maps);
if (test__start_subtest("one-map-two-jumps"))
__subtest(skel, check_one_map_two_jumps);
bpf_gotox__destroy(skel);
}

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@ -0,0 +1,448 @@
// SPDX-License-Identifier: GPL-2.0
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>
#include "bpf_misc.h"
__u64 in_user;
__u64 ret_user;
int pid;
/*
* Skip all the tests if compiler doesn't support indirect jumps.
*
* If tests are skipped, then all functions below are compiled as
* dummy, such that the skeleton looks the same, and the userspace
* program can avoid any checks rather than if data->skip is set.
*/
#ifdef __BPF_FEATURE_GOTOX
__u64 skip SEC(".data") = 0;
#else
__u64 skip = 1;
#endif
struct simple_ctx {
__u64 x;
};
#ifdef __BPF_FEATURE_GOTOX
__u64 some_var;
/*
* This function adds code which will be replaced by a different
* number of instructions by the verifier. This adds additional
* stress on testing the insn_array maps corresponding to indirect jumps.
*/
static __always_inline void adjust_insns(__u64 x)
{
some_var ^= x + bpf_jiffies64();
}
SEC("syscall")
int one_switch(struct simple_ctx *ctx)
{
switch (ctx->x) {
case 0:
adjust_insns(ctx->x + 1);
ret_user = 2;
break;
case 1:
adjust_insns(ctx->x + 7);
ret_user = 3;
break;
case 2:
adjust_insns(ctx->x + 9);
ret_user = 4;
break;
case 3:
adjust_insns(ctx->x + 11);
ret_user = 5;
break;
case 4:
adjust_insns(ctx->x + 17);
ret_user = 7;
break;
default:
adjust_insns(ctx->x + 177);
ret_user = 19;
break;
}
return 0;
}
SEC("syscall")
int one_switch_non_zero_sec_off(struct simple_ctx *ctx)
{
switch (ctx->x) {
case 0:
adjust_insns(ctx->x + 1);
ret_user = 2;
break;
case 1:
adjust_insns(ctx->x + 7);
ret_user = 3;
break;
case 2:
adjust_insns(ctx->x + 9);
ret_user = 4;
break;
case 3:
adjust_insns(ctx->x + 11);
ret_user = 5;
break;
case 4:
adjust_insns(ctx->x + 17);
ret_user = 7;
break;
default:
adjust_insns(ctx->x + 177);
ret_user = 19;
break;
}
return 0;
}
SEC("fentry/" SYS_PREFIX "sys_nanosleep")
int simple_test_other_sec(struct pt_regs *ctx)
{
__u64 x = in_user;
if (bpf_get_current_pid_tgid() >> 32 != pid)
return 0;
switch (x) {
case 0:
adjust_insns(x + 1);
ret_user = 2;
break;
case 1:
adjust_insns(x + 7);
ret_user = 3;
break;
case 2:
adjust_insns(x + 9);
ret_user = 4;
break;
case 3:
adjust_insns(x + 11);
ret_user = 5;
break;
case 4:
adjust_insns(x + 17);
ret_user = 7;
break;
default:
adjust_insns(x + 177);
ret_user = 19;
break;
}
return 0;
}
SEC("syscall")
int two_switches(struct simple_ctx *ctx)
{
switch (ctx->x) {
case 0:
adjust_insns(ctx->x + 1);
ret_user = 2;
break;
case 1:
adjust_insns(ctx->x + 7);
ret_user = 3;
break;
case 2:
adjust_insns(ctx->x + 9);
ret_user = 4;
break;
case 3:
adjust_insns(ctx->x + 11);
ret_user = 5;
break;
case 4:
adjust_insns(ctx->x + 17);
ret_user = 7;
break;
default:
adjust_insns(ctx->x + 177);
ret_user = 19;
break;
}
switch (ctx->x + !!ret_user) {
case 1:
adjust_insns(ctx->x + 7);
ret_user = 103;
break;
case 2:
adjust_insns(ctx->x + 9);
ret_user = 104;
break;
case 3:
adjust_insns(ctx->x + 11);
ret_user = 107;
break;
case 4:
adjust_insns(ctx->x + 11);
ret_user = 205;
break;
case 5:
adjust_insns(ctx->x + 11);
ret_user = 115;
break;
default:
adjust_insns(ctx->x + 177);
ret_user = 1019;
break;
}
return 0;
}
SEC("syscall")
int big_jump_table(struct simple_ctx *ctx __attribute__((unused)))
{
const void *const jt[256] = {
[0 ... 255] = &&default_label,
[0] = &&l0,
[11] = &&l11,
[27] = &&l27,
[31] = &&l31,
};
goto *jt[ctx->x & 0xff];
l0:
adjust_insns(ctx->x + 1);
ret_user = 2;
return 0;
l11:
adjust_insns(ctx->x + 7);
ret_user = 3;
return 0;
l27:
adjust_insns(ctx->x + 9);
ret_user = 4;
return 0;
l31:
adjust_insns(ctx->x + 11);
ret_user = 5;
return 0;
default_label:
adjust_insns(ctx->x + 177);
ret_user = 19;
return 0;
}
SEC("syscall")
int one_jump_two_maps(struct simple_ctx *ctx __attribute__((unused)))
{
__label__ l1, l2, l3, l4;
void *jt1[2] = { &&l1, &&l2 };
void *jt2[2] = { &&l3, &&l4 };
unsigned int a = ctx->x % 2;
unsigned int b = (ctx->x / 2) % 2;
volatile int ret = 0;
if (!(a < 2 && b < 2))
return 19;
if (ctx->x % 2)
goto *jt1[a];
else
goto *jt2[b];
l1: ret += 1;
l2: ret += 3;
l3: ret += 5;
l4: ret += 7;
ret_user = ret;
return ret;
}
SEC("syscall")
int one_map_two_jumps(struct simple_ctx *ctx __attribute__((unused)))
{
__label__ l1, l2, l3;
void *jt[3] = { &&l1, &&l2, &&l3 };
unsigned int a = (ctx->x >> 2) & 1;
unsigned int b = (ctx->x >> 3) & 1;
volatile int ret = 0;
if (ctx->x % 2)
goto *jt[a];
if (ctx->x % 3)
goto *jt[a + b];
l1: ret += 3;
l2: ret += 5;
l3: ret += 7;
ret_user = ret;
return ret;
}
/* Just to introduce some non-zero offsets in .text */
static __noinline int f0(volatile struct simple_ctx *ctx __arg_ctx)
{
if (ctx)
return 1;
else
return 13;
}
SEC("syscall") int f1(struct simple_ctx *ctx)
{
ret_user = 0;
return f0(ctx);
}
static __noinline int __static_global(__u64 x)
{
switch (x) {
case 0:
adjust_insns(x + 1);
ret_user = 2;
break;
case 1:
adjust_insns(x + 7);
ret_user = 3;
break;
case 2:
adjust_insns(x + 9);
ret_user = 4;
break;
case 3:
adjust_insns(x + 11);
ret_user = 5;
break;
case 4:
adjust_insns(x + 17);
ret_user = 7;
break;
default:
adjust_insns(x + 177);
ret_user = 19;
break;
}
return 0;
}
SEC("syscall")
int use_static_global1(struct simple_ctx *ctx)
{
ret_user = 0;
return __static_global(ctx->x);
}
SEC("syscall")
int use_static_global2(struct simple_ctx *ctx)
{
ret_user = 0;
adjust_insns(ctx->x + 1);
return __static_global(ctx->x);
}
SEC("fentry/" SYS_PREFIX "sys_nanosleep")
int use_static_global_other_sec(void *ctx)
{
if (bpf_get_current_pid_tgid() >> 32 != pid)
return 0;
return __static_global(in_user);
}
__noinline int __nonstatic_global(__u64 x)
{
switch (x) {
case 0:
adjust_insns(x + 1);
ret_user = 2;
break;
case 1:
adjust_insns(x + 7);
ret_user = 3;
break;
case 2:
adjust_insns(x + 9);
ret_user = 4;
break;
case 3:
adjust_insns(x + 11);
ret_user = 5;
break;
case 4:
adjust_insns(x + 17);
ret_user = 7;
break;
default:
adjust_insns(x + 177);
ret_user = 19;
break;
}
return 0;
}
SEC("syscall")
int use_nonstatic_global1(struct simple_ctx *ctx)
{
ret_user = 0;
return __nonstatic_global(ctx->x);
}
SEC("syscall")
int use_nonstatic_global2(struct simple_ctx *ctx)
{
ret_user = 0;
adjust_insns(ctx->x + 1);
return __nonstatic_global(ctx->x);
}
SEC("fentry/" SYS_PREFIX "sys_nanosleep")
int use_nonstatic_global_other_sec(void *ctx)
{
if (bpf_get_current_pid_tgid() >> 32 != pid)
return 0;
return __nonstatic_global(in_user);
}
#else /* __BPF_FEATURE_GOTOX */
#define SKIP_TEST(TEST_NAME) \
SEC("syscall") int TEST_NAME(void *ctx) \
{ \
return 0; \
}
SKIP_TEST(one_switch);
SKIP_TEST(one_switch_non_zero_sec_off);
SKIP_TEST(simple_test_other_sec);
SKIP_TEST(two_switches);
SKIP_TEST(big_jump_table);
SKIP_TEST(one_jump_two_maps);
SKIP_TEST(one_map_two_jumps);
SKIP_TEST(use_static_global1);
SKIP_TEST(use_static_global2);
SKIP_TEST(use_static_global_other_sec);
SKIP_TEST(use_nonstatic_global1);
SKIP_TEST(use_nonstatic_global2);
SKIP_TEST(use_nonstatic_global_other_sec);
#endif /* __BPF_FEATURE_GOTOX */
char _license[] SEC("license") = "GPL";