From: Johan Almbladh johan.almbladh@anyfinetworks.com
[ Upstream commit 18935a72eb25525b655262579e1652362a3b29bb ]
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: 874be05f525e ("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@anyfine... Signed-off-by: Sasha Levin sashal@kernel.org --- lib/test_bpf.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-)
diff --git a/lib/test_bpf.c b/lib/test_bpf.c index 830a18ecffc88..68d125b409f20 100644 --- a/lib/test_bpf.c +++ b/lib/test_bpf.c @@ -8992,10 +8992,15 @@ 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 @@ -9065,32 +9070,38 @@ 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, }, };
@@ -9196,6 +9207,8 @@ 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;
@@ -9212,7 +9225,11 @@ 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++;