linux/tools/testing/selftests/bpf/progs/tailcall4.c
Andrii Nakryiko 256eab48e7 selftests/bpf: Stop using static variables for passing data to/from user-space
In preparation of skipping emitting static variables in BPF skeletons, switch
all current selftests uses of static variables to pass data between BPF and
user-space to use global variables.

All non-read-only `static volatile` variables become just plain global
variables by dropping `static volatile` part.

Read-only `static volatile const` variables, though, still require `volatile`
modifier, otherwise compiler will ignore whatever values are set from
user-space.

Few static linker tests are using name-conflicting static variables to
validate that static linker still properly handles static variables and
doesn't trip up on name conflicts.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-4-andrii@kernel.org
2021-05-11 15:07:17 -07:00

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C

// 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, 3);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(__u32));
} jmp_table SEC(".maps");
int selector = 0;
#define TAIL_FUNC(x) \
SEC("classifier/" #x) \
int bpf_func_##x(struct __sk_buff *skb) \
{ \
return x; \
}
TAIL_FUNC(0)
TAIL_FUNC(1)
TAIL_FUNC(2)
SEC("classifier")
int entry(struct __sk_buff *skb)
{
bpf_tail_call(skb, &jmp_table, selector);
return 3;
}
char __license[] SEC("license") = "GPL";
int _version SEC("version") = 1;