Commit 26b367e3 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Andrii Nakryiko
Browse files

selftests/bpf: Additional test for CO-RE in the kernel. 



Add a test where randmap() function is appended to three different bpf
programs. That action checks struct bpf_core_relo replication logic
and offset adjustment in gen loader part of libbpf.

Fourth bpf program has 360 CO-RE relocations from vmlinux, bpf_testmod,
and non-existing type. It tests candidate cache logic.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-16-alexei.starovoitov@gmail.com
parent 650c9dbd

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -326,7 +326,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ 


LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \

	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \

	map_ptr_kern.c

	map_ptr_kern.c core_kern.c

# Generate both light skeleton and libbpf skeleton for these

LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test_subprog.c

SKEL_BLACKLIST += $$(LSKELS)

tools/testing/selftests/bpf/prog_tests/core_kern.c

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+14 −0
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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */



#include "test_progs.h"

#include "core_kern.lskel.h"



void test_core_kern_lskel(void)

{

	struct core_kern_lskel *skel;



	skel = core_kern_lskel__open_and_load();

	ASSERT_OK_PTR(skel, "open_and_load");

	core_kern_lskel__destroy(skel);

}

tools/testing/selftests/bpf/progs/core_kern.c

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+104 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */

#include "vmlinux.h"



#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include <bpf/bpf_core_read.h>



#define ATTR __always_inline

#include "test_jhash.h"



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, u32);

	__type(value, u32);

	__uint(max_entries, 256);

} array1 SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, u32);

	__type(value, u32);

	__uint(max_entries, 256);

} array2 SEC(".maps");



static __noinline int randmap(int v, const struct net_device *dev)

{

	struct bpf_map *map = (struct bpf_map *)&array1;

	int key = bpf_get_prandom_u32() & 0xff;

	int *val;



	if (bpf_get_prandom_u32() & 1)

		map = (struct bpf_map *)&array2;



	val = bpf_map_lookup_elem(map, &key);

	if (val)

		*val = bpf_get_prandom_u32() + v + dev->mtu;



	return 0;

}



SEC("tp_btf/xdp_devmap_xmit")

int BPF_PROG(tp_xdp_devmap_xmit_multi, const struct net_device

	     *from_dev, const struct net_device *to_dev, int sent, int drops,

	     int err)

{

	return randmap(from_dev->ifindex, from_dev);

}



SEC("fentry/eth_type_trans")

int BPF_PROG(fentry_eth_type_trans, struct sk_buff *skb,

	     struct net_device *dev, unsigned short protocol)

{

	return randmap(dev->ifindex + skb->len, dev);

}



SEC("fexit/eth_type_trans")

int BPF_PROG(fexit_eth_type_trans, struct sk_buff *skb,

	     struct net_device *dev, unsigned short protocol)

{

	return randmap(dev->ifindex + skb->len, dev);

}



volatile const int never;



struct __sk_bUfF /* it will not exist in vmlinux */ {

	int len;

} __attribute__((preserve_access_index));



struct bpf_testmod_test_read_ctx /* it exists in bpf_testmod */ {

	size_t len;

} __attribute__((preserve_access_index));



SEC("tc")

int balancer_ingress(struct __sk_buff *ctx)

{

	void *data_end = (void *)(long)ctx->data_end;

	void *data = (void *)(long)ctx->data;

	void *ptr;

	int ret = 0, nh_off, i = 0;



	nh_off = 14;



	/* pragma unroll doesn't work on large loops */

#define C do { \

	ptr = data + i; \

	if (ptr + nh_off > data_end) \

		break; \

	ctx->tc_index = jhash(ptr, nh_off, ctx->cb[0] + i++); \

	if (never) { \

		/* below is a dead code with unresolvable CO-RE relo */ \

		i += ((struct __sk_bUfF *)ctx)->len; \

		/* this CO-RE relo may or may not resolve

		 * depending on whether bpf_testmod is loaded.

		 */ \

		i += ((struct bpf_testmod_test_read_ctx *)ctx)->len; \

	} \

	} while (0);

#define C30 C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;

	C30;C30;C30; /* 90 calls */

	return 0;

}



char LICENSE[] SEC("license") = "GPL";