cachepc-linux

netif_receive_skb.c (8113B)

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020, Oracle and/or its affiliates. */

#include "btf_ptr.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>

#include <errno.h>

long ret = 0;
int num_subtests = 0;
int ran_subtests = 0;
bool skip = false;

#define STRSIZE			2048
#define EXPECTED_STRSIZE	256

#if defined(bpf_target_s390)
/* NULL points to a readable struct lowcore on s390, so take the last page */
#define BADPTR			((void *)0xFFFFFFFFFFFFF000ULL)
#else
#define BADPTR			0
#endif

#ifndef ARRAY_SIZE
#define ARRAY_SIZE(x)	(sizeof(x) / sizeof((x)[0]))
#endif

struct {
	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
	__uint(max_entries, 1);
	__type(key, __u32);
	__type(value, char[STRSIZE]);
} strdata SEC(".maps");

static int __strncmp(const void *m1, const void *m2, size_t len)
{
	const unsigned char *s1 = m1;
	const unsigned char *s2 = m2;
	int i, delta = 0;

	for (i = 0; i < len; i++) {
		delta = s1[i] - s2[i];
		if (delta || s1[i] == 0 || s2[i] == 0)
			break;
	}
	return delta;
}

#if __has_builtin(__builtin_btf_type_id)
#define	TEST_BTF(_str, _type, _flags, _expected, ...)			\
	do {								\
		static const char _expectedval[EXPECTED_STRSIZE] =	\
							_expected;	\
		static const char _ptrtype[64] = #_type;		\
		__u64 _hflags = _flags | BTF_F_COMPACT;			\
		static _type _ptrdata = __VA_ARGS__;			\
		static struct btf_ptr _ptr = { };			\
		int _cmp;						\
									\
		++num_subtests;						\
		if (ret < 0)						\
			break;						\
		++ran_subtests;						\
		_ptr.ptr = &_ptrdata;					\
		_ptr.type_id = bpf_core_type_id_kernel(_type);		\
		if (_ptr.type_id <= 0) {				\
			ret = -EINVAL;					\
			break;						\
		}							\
		ret = bpf_snprintf_btf(_str, STRSIZE,			\
				       &_ptr, sizeof(_ptr), _hflags);	\
		if (ret)						\
			break;						\
		_cmp = __strncmp(_str, _expectedval, EXPECTED_STRSIZE);	\
		if (_cmp != 0) {					\
			bpf_printk("(%d) got %s", _cmp, _str);		\
			bpf_printk("(%d) expected %s", _cmp,		\
				   _expectedval);			\
			ret = -EBADMSG;					\
			break;						\
		}							\
	} while (0)
#endif

/* Use where expected data string matches its stringified declaration */
#define TEST_BTF_C(_str, _type, _flags, ...)				\
	TEST_BTF(_str, _type, _flags, "(" #_type ")" #__VA_ARGS__,	\
		 __VA_ARGS__)

/* TRACE_EVENT(netif_receive_skb,
 *	TP_PROTO(struct sk_buff *skb),
 */
SEC("tp_btf/netif_receive_skb")
int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb)
{
	static __u64 flags[] = { 0, BTF_F_COMPACT, BTF_F_ZERO, BTF_F_PTR_RAW,
				 BTF_F_NONAME, BTF_F_COMPACT | BTF_F_ZERO |
				 BTF_F_PTR_RAW | BTF_F_NONAME };
	static struct btf_ptr p = { };
	__u32 key = 0;
	int i, __ret;
	char *str;

#if __has_builtin(__builtin_btf_type_id)
	str = bpf_map_lookup_elem(&strdata, &key);
	if (!str)
		return 0;

	/* Ensure we can write skb string representation */
	p.type_id = bpf_core_type_id_kernel(struct sk_buff);
	p.ptr = skb;
	for (i = 0; i < ARRAY_SIZE(flags); i++) {
		++num_subtests;
		ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0);
		if (ret < 0)
			bpf_printk("returned %d when writing skb", ret);
		++ran_subtests;
	}

	/* Check invalid ptr value */
	p.ptr = BADPTR;
	__ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0);
	if (__ret >= 0) {
		bpf_printk("printing %llx should generate error, got (%d)",
			   (unsigned long long)BADPTR, __ret);
		ret = -ERANGE;
	}

	/* Verify type display for various types. */

	/* simple int */
	TEST_BTF_C(str, int, 0, 1234);
	TEST_BTF(str, int, BTF_F_NONAME, "1234", 1234);
	/* zero value should be printed at toplevel */
	TEST_BTF(str, int, 0, "(int)0", 0);
	TEST_BTF(str, int, BTF_F_NONAME, "0", 0);
	TEST_BTF(str, int, BTF_F_ZERO, "(int)0", 0);
	TEST_BTF(str, int, BTF_F_NONAME | BTF_F_ZERO, "0", 0);
	TEST_BTF_C(str, int, 0, -4567);
	TEST_BTF(str, int, BTF_F_NONAME, "-4567", -4567);

	/* simple char */
	TEST_BTF_C(str, char, 0, 100);
	TEST_BTF(str, char, BTF_F_NONAME, "100", 100);
	/* zero value should be printed at toplevel */
	TEST_BTF(str, char, 0, "(char)0", 0);
	TEST_BTF(str, char, BTF_F_NONAME, "0", 0);
	TEST_BTF(str, char, BTF_F_ZERO, "(char)0", 0);
	TEST_BTF(str, char, BTF_F_NONAME | BTF_F_ZERO, "0", 0);

	/* simple typedef */
	TEST_BTF_C(str, uint64_t, 0, 100);
	TEST_BTF(str, u64, BTF_F_NONAME, "1", 1);
	/* zero value should be printed at toplevel */
	TEST_BTF(str, u64, 0, "(u64)0", 0);
	TEST_BTF(str, u64, BTF_F_NONAME, "0", 0);
	TEST_BTF(str, u64, BTF_F_ZERO, "(u64)0", 0);
	TEST_BTF(str, u64, BTF_F_NONAME|BTF_F_ZERO, "0", 0);

	/* typedef struct */
	TEST_BTF_C(str, atomic_t, 0, {.counter = (int)1,});
	TEST_BTF(str, atomic_t, BTF_F_NONAME, "{1,}", {.counter = 1,});
	/* typedef with 0 value should be printed at toplevel */
	TEST_BTF(str, atomic_t, 0, "(atomic_t){}", {.counter = 0,});
	TEST_BTF(str, atomic_t, BTF_F_NONAME, "{}", {.counter = 0,});
	TEST_BTF(str, atomic_t, BTF_F_ZERO, "(atomic_t){.counter = (int)0,}",
		 {.counter = 0,});
	TEST_BTF(str, atomic_t, BTF_F_NONAME|BTF_F_ZERO,
		 "{0,}", {.counter = 0,});

	/* enum where enum value does (and does not) exist */
	TEST_BTF_C(str, enum bpf_cmd, 0, BPF_MAP_CREATE);
	TEST_BTF(str, enum bpf_cmd, 0, "(enum bpf_cmd)BPF_MAP_CREATE", 0);
	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME, "BPF_MAP_CREATE",
		 BPF_MAP_CREATE);
	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME|BTF_F_ZERO,
		 "BPF_MAP_CREATE", 0);

	TEST_BTF(str, enum bpf_cmd, BTF_F_ZERO, "(enum bpf_cmd)BPF_MAP_CREATE",
		 BPF_MAP_CREATE);
	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME|BTF_F_ZERO,
		 "BPF_MAP_CREATE", BPF_MAP_CREATE);
	TEST_BTF_C(str, enum bpf_cmd, 0, 2000);
	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME, "2000", 2000);

	/* simple struct */
	TEST_BTF_C(str, struct btf_enum, 0,
		   {.name_off = (__u32)3,.val = (__s32)-1,});
	TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{3,-1,}",
		 { .name_off = 3, .val = -1,});
	TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{-1,}",
		 { .name_off = 0, .val = -1,});
	TEST_BTF(str, struct btf_enum, BTF_F_NONAME|BTF_F_ZERO, "{0,-1,}",
		 { .name_off = 0, .val = -1,});
	/* empty struct should be printed */
	TEST_BTF(str, struct btf_enum, 0, "(struct btf_enum){}",
		 { .name_off = 0, .val = 0,});
	TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{}",
		 { .name_off = 0, .val = 0,});
	TEST_BTF(str, struct btf_enum, BTF_F_ZERO,
		 "(struct btf_enum){.name_off = (__u32)0,.val = (__s32)0,}",
		 { .name_off = 0, .val = 0,});

	/* struct with pointers */
	TEST_BTF(str, struct list_head, BTF_F_PTR_RAW,
		 "(struct list_head){.next = (struct list_head *)0x0000000000000001,}",
		 { .next = (struct list_head *)1 });
	/* NULL pointer should not be displayed */
	TEST_BTF(str, struct list_head, BTF_F_PTR_RAW,
		 "(struct list_head){}",
		 { .next = (struct list_head *)0 });

	/* struct with char array */
	TEST_BTF(str, struct bpf_prog_info, 0,
		 "(struct bpf_prog_info){.name = (char[])['f','o','o',],}",
		 { .name = "foo",});
	TEST_BTF(str, struct bpf_prog_info, BTF_F_NONAME,
		 "{['f','o','o',],}",
		 {.name = "foo",});
	/* leading null char means do not display string */
	TEST_BTF(str, struct bpf_prog_info, 0,
		 "(struct bpf_prog_info){}",
		 {.name = {'\0', 'f', 'o', 'o'}});
	/* handle non-printable characters */
	TEST_BTF(str, struct bpf_prog_info, 0,
		 "(struct bpf_prog_info){.name = (char[])[1,2,3,],}",
		 { .name = {1, 2, 3, 0}});

	/* struct with non-char array */
	TEST_BTF(str, struct __sk_buff, 0,
		 "(struct __sk_buff){.cb = (__u32[])[1,2,3,4,5,],}",
		 { .cb = {1, 2, 3, 4, 5,},});
	TEST_BTF(str, struct __sk_buff, BTF_F_NONAME,
		 "{[1,2,3,4,5,],}",
		 { .cb = { 1, 2, 3, 4, 5},});
	/* For non-char, arrays, show non-zero values only */
	TEST_BTF(str, struct __sk_buff, 0,
		 "(struct __sk_buff){.cb = (__u32[])[1,],}",
		 { .cb = { 0, 0, 1, 0, 0},});

	/* struct with bitfields */
	TEST_BTF_C(str, struct bpf_insn, 0,
		   {.code = (__u8)1,.dst_reg = (__u8)0x2,.src_reg = (__u8)0x3,.off = (__s16)4,.imm = (__s32)5,});
	TEST_BTF(str, struct bpf_insn, BTF_F_NONAME, "{1,0x2,0x3,4,5,}",
		 {.code = 1, .dst_reg = 0x2, .src_reg = 0x3, .off = 4,
		  .imm = 5,});
#else
	skip = true;
#endif

	return 0;
}

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