On Wed, Sep 02, 2020 at 10:08:15PM +0200, Maciej Fijalkowski wrote:
> diff --git a/tools/testing/selftests/bpf/progs/tailcall6.c b/tools/testing/selftests/bpf/progs/tailcall6.c
> new file mode 100644
> index 000000000000..e72ca5869b58
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/tailcall6.c
> @@ -0,0 +1,38 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
> + __uint(max_entries, 2);
> + __uint(key_size, sizeof(__u32));
> + __uint(value_size, sizeof(__u32));
> +} jmp_table SEC(".maps");
> +
> +#define TAIL_FUNC(x) \
> + SEC("classifier/" #x) \
> + int bpf_func_##x(struct __sk_buff *skb) \
> + { \
> + return x; \
> + }
> +TAIL_FUNC(0)
> +TAIL_FUNC(1)
> +
> +static __attribute__ ((noinline))
> +int subprog_tail(struct __sk_buff *skb)
> +{
> + bpf_tail_call(skb, &jmp_table, 0);
> +
> + return skb->len * 2;
> +}
> +
> +SEC("classifier")
> +int entry(struct __sk_buff *skb)
> +{
> + bpf_tail_call(skb, &jmp_table, 1);
> +
> + return subprog_tail(skb);
> +}
Could you add few more tests to exercise the new feature more thoroughly?
Something like tailcall3.c that checks 32 limit, but doing tail_call from subprog.
And another test that consume non-trival amount of stack in each function.
Adding 'volatile char arr[128] = {};' would do the trick.
