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bpf/tests: Fix error in tail call limit tests

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This patch fixes an error in the tail call limit test that caused the
test to fail on for x86-64 JIT. Previously, the register R0 was used to
report the total number of tail calls made. However, after a tail call
fall-through, the value of the R0 register is undefined. Now, all tail
call error path tests instead use context state to store the count.

Fixes: 874be05f52 ("bpf, tests: Add tail call test suite")
Reported-by: Paul Chaignon <paul@cilium.io>
Reported-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/bpf/20210914091842.4186267-14-johan.almbladh@anyfinetworks.com
This commit is contained in:
Johan Almbladh 2021-09-14 11:18:41 +02:00 committed by Daniel Borkmann
parent f536a7c806
commit 18935a72eb
1 changed files with 27 additions and 10 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

37
lib/test_bpf.c
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@ -12180,10 +12180,15 @@ static __init int test_bpf(void)
struct tail_call_test {
const char *descr;
struct bpf_insn insns[MAX_INSNS];
int flags;
int result;
int stack_depth;
};
/* Flags that can be passed to tail call test cases */
#define FLAG_NEED_STATE BIT(0)
#define FLAG_RESULT_IN_STATE BIT(1)
/*
* Magic marker used in test snippets for tail calls below.
* BPF_LD/MOV to R2 and R2 with this immediate value is replaced
@ -12253,32 +12258,38 @@ static struct tail_call_test tail_call_tests[] = {
{
"Tail call error path, max count reached",
.insns = {
BPF_ALU64_IMM(BPF_ADD, R1, 1),
BPF_ALU64_REG(BPF_MOV, R0, R1),
BPF_LDX_MEM(BPF_W, R2, R1, 0),
BPF_ALU64_IMM(BPF_ADD, R2, 1),
BPF_STX_MEM(BPF_W, R1, R2, 0),
TAIL_CALL(0),
BPF_EXIT_INSN(),
},
.result = MAX_TAIL_CALL_CNT + 1,
.flags = FLAG_NEED_STATE | FLAG_RESULT_IN_STATE,
.result = (MAX_TAIL_CALL_CNT + 1 + 1) * MAX_TESTRUNS,
},
{
"Tail call error path, NULL target",
.insns = {
BPF_ALU64_IMM(BPF_MOV, R0, -1),
BPF_LDX_MEM(BPF_W, R2, R1, 0),
BPF_ALU64_IMM(BPF_ADD, R2, 1),
BPF_STX_MEM(BPF_W, R1, R2, 0),
TAIL_CALL(TAIL_CALL_NULL),
BPF_ALU64_IMM(BPF_MOV, R0, 1),
BPF_EXIT_INSN(),
},
.result = 1,
.flags = FLAG_NEED_STATE | FLAG_RESULT_IN_STATE,
.result = MAX_TESTRUNS,
},
{
"Tail call error path, index out of range",
.insns = {
BPF_ALU64_IMM(BPF_MOV, R0, -1),
BPF_LDX_MEM(BPF_W, R2, R1, 0),
BPF_ALU64_IMM(BPF_ADD, R2, 1),
BPF_STX_MEM(BPF_W, R1, R2, 0),
TAIL_CALL(TAIL_CALL_INVALID),
BPF_ALU64_IMM(BPF_MOV, R0, 1),
BPF_EXIT_INSN(),
},
.result = 1,
.flags = FLAG_NEED_STATE | FLAG_RESULT_IN_STATE,
.result = MAX_TESTRUNS,
},
};
@ -12384,6 +12395,8 @@ static __init int test_tail_calls(struct bpf_array *progs)
for (i = 0; i < ARRAY_SIZE(tail_call_tests); i++) {
struct tail_call_test *test = &tail_call_tests[i];
struct bpf_prog *fp = progs->ptrs[i];
int *data = NULL;
int state = 0;
u64 duration;
int ret;
@ -12400,7 +12413,11 @@ static __init int test_tail_calls(struct bpf_array *progs)
if (fp->jited)
jit_cnt++;
ret = __run_one(fp, NULL, MAX_TESTRUNS, &duration);
if (test->flags & FLAG_NEED_STATE)
data = &state;
ret = __run_one(fp, data, MAX_TESTRUNS, &duration);
if (test->flags & FLAG_RESULT_IN_STATE)
ret = state;
if (ret == test->result) {
pr_cont("%lld PASS", duration);
pass_cnt++;