Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> Add tests for may_goto instruction via cond_break macro.
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
> tools/testing/selftests/bpf/DENYLIST.s390x | 1 +
> .../bpf/progs/verifier_iterating_callbacks.c | 72 ++++++++++++++++++-
> 2 files changed, 70 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
> index 1a63996c0304..c6c31b960810 100644
> --- a/tools/testing/selftests/bpf/DENYLIST.s390x
> +++ b/tools/testing/selftests/bpf/DENYLIST.s390x
> @@ -3,3 +3,4 @@
> exceptions # JIT does not support calling kfunc bpf_throw (exceptions)
> get_stack_raw_tp # user_stack corrupted user stack (no backchain userspace)
> stacktrace_build_id # compare_map_keys stackid_hmap vs. stackmap err -2 errno 2 (?)
> +verifier_iter/cond_break
> diff --git a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
> index 5905e036e0ea..8476dc47623f 100644
> --- a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
> +++ b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
> @@ -1,8 +1,6 @@
> // SPDX-License-Identifier: GPL-2.0
> -
> -#include <linux/bpf.h>
> -#include <bpf/bpf_helpers.h>
> #include "bpf_misc.h"
> +#include "bpf_experimental.h"
>
> struct {
> __uint(type, BPF_MAP_TYPE_ARRAY);
> @@ -239,4 +237,72 @@ int bpf_loop_iter_limit_nested(void *unused)
> return 1000 * a + b + c;
> }
>
> +#define ARR_SZ 1000000
> +int zero;
> +char arr[ARR_SZ];
> +
> +SEC("socket")
> +__success __retval(0xd495cdc0)
> +int cond_break1(const void *ctx)
> +{
> + unsigned int i;
> + unsigned int sum = 0;
> +
> + for (i = zero; i < ARR_SZ; cond_break, i++)
> + sum += i;
> + for (i = zero; i < ARR_SZ; i++) {
> + barrier_var(i);
> + sum += i + arr[i];
> + cond_break;
> + }
> +
> + return sum;
> +}
> +
> +SEC("socket")
> +__success __retval(999000000)
> +int cond_break2(const void *ctx)
> +{
> + int i, j;
> + int sum = 0;
> +
> + for (i = zero; i < 1000; cond_break, i++)
> + for (j = zero; j < 1000; j++) {
> + sum += i + j;
> + cond_break;
> + }
> +
> + return sum;
> +}
> +
> +static __noinline int loop(void)
> +{
> + int i, sum = 0;
> +
> + for (i = zero; i <= 1000000; i++, cond_break)
> + sum += i;
> +
> + return sum;
> +}
> +
> +SEC("socket")
> +__success __retval(0x6a5a2920)
> +int cond_break3(const void *ctx)
> +{
> + return loop();
> +}
> +
> +SEC("socket")
> +__success __retval(0x800000) /* BPF_MAX_LOOPS */
> +int cond_break4(const void *ctx)
> +{
> + int cnt = 0;
> +
> + for (;;) {
> + cond_break;
> + cnt++;
> + }
> + return cnt;
> +}
I found this test illustrative to show how the cond_break which
is to me "feels" like a global hidden iterator appears to not
be reinitialized across calls?
static __noinline int full_loop(void)
{
int cnt = 0;
for (;;) {
cond_break;
cnt++;
}
for (;;) {
cond_break;
cnt++;
}
bpf_printk("cnt==%d\n", cnt);
return cnt;
}
SEC("socket")
__success __retval(16777216)
int cond_break5(const void *ctx)
{
int cnt = 0;
for (;;) {
cond_break;
cnt++;
}
cnt += full_loop();
for (;;) {
cond_break;
cnt++;
}
return cnt;
}
This fails with,
do_prog_test_run:PASS:bpf_prog_test_run 0 nsec
run_subtest:FAIL:654 Unexpected retval: 8388608 != 16777216
#430/15 verifier_iterating_callbacks/cond_break5:FAIL
#430 verifier_iterating_callbacks:FAIL
; cnt += full_loop();
118: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll
120: b4 02 00 00 0d 00 00 00 w2 = 13
121: bc 73 00 00 00 00 00 00 w3 = w7
122: 85 00 00 00 06 00 00 00 call 6
;
I guess this is by design but I sort of expected each
call to have its own context. It does make some sense to
limit main and all calls to a max loop count so not
complaining. Maybe consider adding the test? I at least
thought it helped.
> +
> char _license[] SEC("license") = "GPL";
> --
> 2.34.1
>
>
