bpf, tests: Add tail call test suite
While BPF_CALL instructions were tested implicitly by the cBPF-to-eBPF translation, there has not been any tests for BPF_TAIL_CALL instructions. The new test suite includes tests for tail call chaining, tail call count tracking and error paths. It is mainly intended for JIT development and testing. Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210809091829.810076-15-johan.almbladh@anyfinetworks.com
This commit is contained in:
Johan Almbladh
Daniel Borkmann
parent
6a3b24ca48
commit
874be05f52
248
lib/test_bpf.c
248
lib/test_bpf.c
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@ -8989,8 +8989,248 @@ static __init int test_bpf(void)
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return err_cnt ? -EINVAL : 0;
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}
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struct tail_call_test {
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const char *descr;
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struct bpf_insn insns[MAX_INSNS];
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int result;
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int stack_depth;
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};
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/*
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* Magic marker used in test snippets for tail calls below.
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* BPF_LD/MOV to R2 and R2 with this immediate value is replaced
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* with the proper values by the test runner.
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*/
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#define TAIL_CALL_MARKER 0x7a11ca11
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/* Special offset to indicate a NULL call target */
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#define TAIL_CALL_NULL 0x7fff
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/* Special offset to indicate an out-of-range index */
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#define TAIL_CALL_INVALID 0x7ffe
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#define TAIL_CALL(offset) \
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BPF_LD_IMM64(R2, TAIL_CALL_MARKER), \
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BPF_RAW_INSN(BPF_ALU | BPF_MOV | BPF_K, R3, 0, \
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offset, TAIL_CALL_MARKER), \
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BPF_JMP_IMM(BPF_TAIL_CALL, 0, 0, 0)
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/*
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* Tail call tests. Each test case may call any other test in the table,
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* including itself, specified as a relative index offset from the calling
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* test. The index TAIL_CALL_NULL can be used to specify a NULL target
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* function to test the JIT error path. Similarly, the index TAIL_CALL_INVALID
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* results in a target index that is out of range.
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*/
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static struct tail_call_test tail_call_tests[] = {
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{
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"Tail call leaf",
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.insns = {
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BPF_ALU64_REG(BPF_MOV, R0, R1),
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BPF_ALU64_IMM(BPF_ADD, R0, 1),
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BPF_EXIT_INSN(),
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},
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.result = 1,
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},
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{
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"Tail call 2",
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.insns = {
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BPF_ALU64_IMM(BPF_ADD, R1, 2),
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TAIL_CALL(-1),
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BPF_ALU64_IMM(BPF_MOV, R0, -1),
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BPF_EXIT_INSN(),
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},
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.result = 3,
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},
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{
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"Tail call 3",
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.insns = {
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BPF_ALU64_IMM(BPF_ADD, R1, 3),
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TAIL_CALL(-1),
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BPF_ALU64_IMM(BPF_MOV, R0, -1),
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BPF_EXIT_INSN(),
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},
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.result = 6,
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},
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{
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"Tail call 4",
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.insns = {
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BPF_ALU64_IMM(BPF_ADD, R1, 4),
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TAIL_CALL(-1),
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BPF_ALU64_IMM(BPF_MOV, R0, -1),
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BPF_EXIT_INSN(),
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},
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.result = 10,
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},
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{
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"Tail call error path, max count reached",
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.insns = {
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BPF_ALU64_IMM(BPF_ADD, R1, 1),
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BPF_ALU64_REG(BPF_MOV, R0, R1),
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TAIL_CALL(0),
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BPF_EXIT_INSN(),
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},
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.result = MAX_TAIL_CALL_CNT + 1,
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},
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{
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"Tail call error path, NULL target",
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.insns = {
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BPF_ALU64_IMM(BPF_MOV, R0, -1),
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TAIL_CALL(TAIL_CALL_NULL),
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BPF_ALU64_IMM(BPF_MOV, R0, 1),
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BPF_EXIT_INSN(),
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},
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.result = 1,
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},
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{
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"Tail call error path, index out of range",
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.insns = {
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BPF_ALU64_IMM(BPF_MOV, R0, -1),
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TAIL_CALL(TAIL_CALL_INVALID),
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BPF_ALU64_IMM(BPF_MOV, R0, 1),
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BPF_EXIT_INSN(),
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},
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.result = 1,
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},
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};
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static void __init destroy_tail_call_tests(struct bpf_array *progs)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(tail_call_tests); i++)
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if (progs->ptrs[i])
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bpf_prog_free(progs->ptrs[i]);
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kfree(progs);
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}
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static __init int prepare_tail_call_tests(struct bpf_array **pprogs)
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{
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int ntests = ARRAY_SIZE(tail_call_tests);
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struct bpf_array *progs;
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int which, err;
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/* Allocate the table of programs to be used for tall calls */
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progs = kzalloc(sizeof(*progs) + (ntests + 1) * sizeof(progs->ptrs[0]),
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GFP_KERNEL);
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if (!progs)
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goto out_nomem;
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/* Create all eBPF programs and populate the table */
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for (which = 0; which < ntests; which++) {
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struct tail_call_test *test = &tail_call_tests[which];
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struct bpf_prog *fp;
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int len, i;
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/* Compute the number of program instructions */
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for (len = 0; len < MAX_INSNS; len++) {
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struct bpf_insn *insn = &test->insns[len];
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if (len < MAX_INSNS - 1 &&
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insn->code == (BPF_LD | BPF_DW | BPF_IMM))
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len++;
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if (insn->code == 0)
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break;
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}
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/* Allocate and initialize the program */
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fp = bpf_prog_alloc(bpf_prog_size(len), 0);
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if (!fp)
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goto out_nomem;
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fp->len = len;
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fp->type = BPF_PROG_TYPE_SOCKET_FILTER;
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fp->aux->stack_depth = test->stack_depth;
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memcpy(fp->insnsi, test->insns, len * sizeof(struct bpf_insn));
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/* Relocate runtime tail call offsets and addresses */
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for (i = 0; i < len; i++) {
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struct bpf_insn *insn = &fp->insnsi[i];
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if (insn->imm != TAIL_CALL_MARKER)
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continue;
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switch (insn->code) {
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case BPF_LD | BPF_DW | BPF_IMM:
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insn[0].imm = (u32)(long)progs;
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insn[1].imm = ((u64)(long)progs) >> 32;
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break;
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case BPF_ALU | BPF_MOV | BPF_K:
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if (insn->off == TAIL_CALL_NULL)
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insn->imm = ntests;
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else if (insn->off == TAIL_CALL_INVALID)
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insn->imm = ntests + 1;
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else
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insn->imm = which + insn->off;
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insn->off = 0;
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}
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}
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fp = bpf_prog_select_runtime(fp, &err);
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if (err)
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goto out_err;
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progs->ptrs[which] = fp;
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}
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/* The last entry contains a NULL program pointer */
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progs->map.max_entries = ntests + 1;
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*pprogs = progs;
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return 0;
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out_nomem:
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err = -ENOMEM;
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out_err:
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if (progs)
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destroy_tail_call_tests(progs);
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return err;
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}
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static __init int test_tail_calls(struct bpf_array *progs)
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{
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int i, err_cnt = 0, pass_cnt = 0;
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int jit_cnt = 0, run_cnt = 0;
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for (i = 0; i < ARRAY_SIZE(tail_call_tests); i++) {
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struct tail_call_test *test = &tail_call_tests[i];
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struct bpf_prog *fp = progs->ptrs[i];
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u64 duration;
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int ret;
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cond_resched();
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pr_info("#%d %s ", i, test->descr);
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if (!fp) {
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err_cnt++;
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continue;
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}
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pr_cont("jited:%u ", fp->jited);
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run_cnt++;
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if (fp->jited)
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jit_cnt++;
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ret = __run_one(fp, NULL, MAX_TESTRUNS, &duration);
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if (ret == test->result) {
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pr_cont("%lld PASS", duration);
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pass_cnt++;
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} else {
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pr_cont("ret %d != %d FAIL", ret, test->result);
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err_cnt++;
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}
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}
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pr_info("%s: Summary: %d PASSED, %d FAILED, [%d/%d JIT'ed]\n",
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__func__, pass_cnt, err_cnt, jit_cnt, run_cnt);
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return err_cnt ? -EINVAL : 0;
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}
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static int __init test_bpf_init(void)
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{
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struct bpf_array *progs = NULL;
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int ret;
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ret = prepare_bpf_tests();
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@ -9002,6 +9242,14 @@ static int __init test_bpf_init(void)
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if (ret)
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return ret;
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ret = prepare_tail_call_tests(&progs);
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if (ret)
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return ret;
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ret = test_tail_calls(progs);
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destroy_tail_call_tests(progs);
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if (ret)
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return ret;
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return test_skb_segment();
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}
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