selftests/bpf: add realistic loop tests

Add a bunch of loop tests. Most of them are created by replacing
'#pragma unroll' with '#pragma clang loop unroll(disable)'

Several tests are artificially large:
  /* partial unroll. llvm will unroll loop ~150 times.
   * C loop count -> 600.
   * Asm loop count -> 4.
   * 16k insns in loop body.
   * Total of 5 such loops. Total program size ~82k insns.
   */
  "./pyperf600.o",

  /* no unroll at all.
   * C loop count -> 600.
   * ASM loop count -> 600.
   * ~110 insns in loop body.
   * Total of 5 such loops. Total program size ~1500 insns.
   */
  "./pyperf600_nounroll.o",

  /* partial unroll. 19k insn in a loop.
   * Total program size 20.8k insn.
   * ~350k processed_insns
   */
  "./strobemeta.o",
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

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

@@ -5,7 +5,7 @@ static int libbpf_debug_print(enum libbpf_print_level level,
 			      const char *format, va_list args)
 {
 	if (level != LIBBPF_DEBUG)
-		return 0;
+		return vfprintf(stderr, format, args);
 
 	if (!strstr(format, "verifier log"))
 		return 0;
@@ -32,24 +32,69 @@ static int check_load(const char *file, enum bpf_prog_type type)
 
 void test_bpf_verif_scale(void)
 {
-	const char *scale[] = {
-		"./test_verif_scale1.o", "./test_verif_scale2.o", "./test_verif_scale3.o"
+	const char *sched_cls[] = {
+		"./test_verif_scale1.o", "./test_verif_scale2.o", "./test_verif_scale3.o",
 	};
-	const char *pyperf[] = {
-		"./pyperf50.o",	"./pyperf100.o", "./pyperf180.o"
+	const char *raw_tp[] = {
+		/* full unroll by llvm */
+		"./pyperf50.o",	"./pyperf100.o", "./pyperf180.o",
+
+		/* partial unroll. llvm will unroll loop ~150 times.
+		 * C loop count -> 600.
+		 * Asm loop count -> 4.
+		 * 16k insns in loop body.
+		 * Total of 5 such loops. Total program size ~82k insns.
+		 */
+		"./pyperf600.o",
+
+		/* no unroll at all.
+		 * C loop count -> 600.
+		 * ASM loop count -> 600.
+		 * ~110 insns in loop body.
+		 * Total of 5 such loops. Total program size ~1500 insns.
+		 */
+		"./pyperf600_nounroll.o",
+
+		"./loop1.o", "./loop2.o",
+
+		/* partial unroll. 19k insn in a loop.
+		 * Total program size 20.8k insn.
+		 * ~350k processed_insns
+		 */
+		"./strobemeta.o",
+
+		/* no unroll, tiny loops */
+		"./strobemeta_nounroll1.o",
+		"./strobemeta_nounroll2.o",
+	};
+	const char *cg_sysctl[] = {
+		"./test_sysctl_loop1.o", "./test_sysctl_loop2.o",
 	};
 	int err, i;
 
 	if (verifier_stats)
 		libbpf_set_print(libbpf_debug_print);
 
-	for (i = 0; i < ARRAY_SIZE(scale); i++) {
-		err = check_load(scale[i], BPF_PROG_TYPE_SCHED_CLS);
-		printf("test_scale:%s:%s\n", scale[i], err ? "FAIL" : "OK");
+	err = check_load("./loop3.o", BPF_PROG_TYPE_RAW_TRACEPOINT);
+	printf("test_scale:loop3:%s\n", err ? (error_cnt--, "OK") : "FAIL");
+
+	for (i = 0; i < ARRAY_SIZE(sched_cls); i++) {
+		err = check_load(sched_cls[i], BPF_PROG_TYPE_SCHED_CLS);
+		printf("test_scale:%s:%s\n", sched_cls[i], err ? "FAIL" : "OK");
 	}
 
-	for (i = 0; i < ARRAY_SIZE(pyperf); i++) {
-		err = check_load(pyperf[i], BPF_PROG_TYPE_RAW_TRACEPOINT);
-		printf("test_scale:%s:%s\n", pyperf[i], err ? "FAIL" : "OK");
+	for (i = 0; i < ARRAY_SIZE(raw_tp); i++) {
+		err = check_load(raw_tp[i], BPF_PROG_TYPE_RAW_TRACEPOINT);
+		printf("test_scale:%s:%s\n", raw_tp[i], err ? "FAIL" : "OK");
 	}
+
+	for (i = 0; i < ARRAY_SIZE(cg_sysctl); i++) {
+		err = check_load(cg_sysctl[i], BPF_PROG_TYPE_CGROUP_SYSCTL);
+		printf("test_scale:%s:%s\n", cg_sysctl[i], err ? "FAIL" : "OK");
+	}
+	err = check_load("./test_xdp_loop.o", BPF_PROG_TYPE_XDP);
+	printf("test_scale:test_xdp_loop:%s\n", err ? "FAIL" : "OK");
+
+	err = check_load("./test_seg6_loop.o", BPF_PROG_TYPE_LWT_SEG6LOCAL);
+	printf("test_scale:test_seg6_loop:%s\n", err ? "FAIL" : "OK");
 }

tools/testing/selftests/bpf/progs/loop1.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("raw_tracepoint/kfree_skb")
+int nested_loops(volatile struct pt_regs* ctx)
+{
+	int i, j, sum = 0, m;
+
+	for (j = 0; j < 300; j++)
+		for (i = 0; i < j; i++) {
+			if (j & 1)
+				m = ctx->rax;
+			else
+				m = j;
+			sum += i * m;
+		}
+
+	return sum;
+}

tools/testing/selftests/bpf/progs/loop2.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("raw_tracepoint/consume_skb")
+int while_true(volatile struct pt_regs* ctx)
+{
+	int i = 0;
+
+	while (true) {
+		if (ctx->rax & 1)
+			i += 3;
+		else
+			i += 7;
+		if (i > 40)
+			break;
+	}
+
+	return i;
+}

tools/testing/selftests/bpf/progs/loop3.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("raw_tracepoint/consume_skb")
+int while_true(volatile struct pt_regs* ctx)
+{
+	__u64 i = 0, sum = 0;
+	do {
+		i++;
+		sum += ctx->rax;
+	} while (i < 0x100000000ULL);
+	return sum;
+}

tools/testing/selftests/bpf/progs/pyperf.h

@@ -220,7 +220,11 @@ static inline __attribute__((__always_inline__)) int __on_event(struct pt_regs *
 		int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym);
 		if (symbol_counter == NULL)
 			return 0;
-#pragma unroll
+#ifdef NO_UNROLL
+#pragma clang loop unroll(disable)
+#else
+#pragma clang loop unroll(full)
+#endif
 		/* Unwind python stack */
 		for (int i = 0; i < STACK_MAX_LEN; ++i) {
 			if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) {

tools/testing/selftests/bpf/progs/pyperf600.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#define STACK_MAX_LEN 600
+/* clang will not unroll the loop 600 times.
+ * Instead it will unroll it to the amount it deemed
+ * appropriate, but the loop will still execute 600 times.
+ * Total program size is around 90k insns
+ */
+#include "pyperf.h"

tools/testing/selftests/bpf/progs/pyperf600_nounroll.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#define STACK_MAX_LEN 600
+#define NO_UNROLL
+/* clang will not unroll at all.
+ * Total program size is around 2k insns
+ */
+#include "pyperf.h"

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

+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+// Copyright (c) 2019 Facebook
+
+#define STROBE_MAX_INTS 2
+#define STROBE_MAX_STRS 25
+#define STROBE_MAX_MAPS 100
+#define STROBE_MAX_MAP_ENTRIES 20
+/* full unroll by llvm #undef NO_UNROLL */
+#include "strobemeta.h"
+

tools/testing/selftests/bpf/progs/strobemeta_nounroll1.c

+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+// Copyright (c) 2019 Facebook
+
+#define STROBE_MAX_INTS 2
+#define STROBE_MAX_STRS 25
+#define STROBE_MAX_MAPS 13
+#define STROBE_MAX_MAP_ENTRIES 20
+#define NO_UNROLL
+#include "strobemeta.h"

tools/testing/selftests/bpf/progs/strobemeta_nounroll2.c

+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+// Copyright (c) 2019 Facebook
+
+#define STROBE_MAX_INTS 2
+#define STROBE_MAX_STRS 25
+#define STROBE_MAX_MAPS 30
+#define STROBE_MAX_MAP_ENTRIES 20
+#define NO_UNROLL
+#include "strobemeta.h"

tools/testing/selftests/bpf/progs/test_seg6_loop.c

+#include <stddef.h>
+#include <inttypes.h>
+#include <errno.h>
+#include <linux/seg6_local.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+/* Packet parsing state machine helpers. */
+#define cursor_advance(_cursor, _len) \
+	({ void *_tmp = _cursor; _cursor += _len; _tmp; })
+
+#define SR6_FLAG_ALERT (1 << 4)
+
+#define htonll(x) ((bpf_htonl(1)) == 1 ? (x) : ((uint64_t)bpf_htonl((x) & \
+				0xFFFFFFFF) << 32) | bpf_htonl((x) >> 32))
+#define ntohll(x) ((bpf_ntohl(1)) == 1 ? (x) : ((uint64_t)bpf_ntohl((x) & \
+				0xFFFFFFFF) << 32) | bpf_ntohl((x) >> 32))
+#define BPF_PACKET_HEADER __attribute__((packed))
+
+struct ip6_t {
+	unsigned int ver:4;
+	unsigned int priority:8;
+	unsigned int flow_label:20;
+	unsigned short payload_len;
+	unsigned char next_header;
+	unsigned char hop_limit;
+	unsigned long long src_hi;
+	unsigned long long src_lo;
+	unsigned long long dst_hi;
+	unsigned long long dst_lo;
+} BPF_PACKET_HEADER;
+
+struct ip6_addr_t {
+	unsigned long long hi;
+	unsigned long long lo;
+} BPF_PACKET_HEADER;
+
+struct ip6_srh_t {
+	unsigned char nexthdr;
+	unsigned char hdrlen;
+	unsigned char type;
+	unsigned char segments_left;
+	unsigned char first_segment;
+	unsigned char flags;
+	unsigned short tag;
+
+	struct ip6_addr_t segments[0];
+} BPF_PACKET_HEADER;
+
+struct sr6_tlv_t {
+	unsigned char type;
+	unsigned char len;
+	unsigned char value[0];
+} BPF_PACKET_HEADER;
+
+static __attribute__((always_inline)) struct ip6_srh_t *get_srh(struct __sk_buff *skb)
+{
+	void *cursor, *data_end;
+	struct ip6_srh_t *srh;
+	struct ip6_t *ip;
+	uint8_t *ipver;
+
+	data_end = (void *)(long)skb->data_end;
+	cursor = (void *)(long)skb->data;
+	ipver = (uint8_t *)cursor;
+
+	if ((void *)ipver + sizeof(*ipver) > data_end)
+		return NULL;
+
+	if ((*ipver >> 4) != 6)
+		return NULL;
+
+	ip = cursor_advance(cursor, sizeof(*ip));
+	if ((void *)ip + sizeof(*ip) > data_end)
+		return NULL;
+
+	if (ip->next_header != 43)
+		return NULL;
+
+	srh = cursor_advance(cursor, sizeof(*srh));
+	if ((void *)srh + sizeof(*srh) > data_end)
+		return NULL;
+
+	if (srh->type != 4)
+		return NULL;
+
+	return srh;
+}
+
+static __attribute__((always_inline))
+int update_tlv_pad(struct __sk_buff *skb, uint32_t new_pad,
+		   uint32_t old_pad, uint32_t pad_off)
+{
+	int err;
+
+	if (new_pad != old_pad) {
+		err = bpf_lwt_seg6_adjust_srh(skb, pad_off,
+					  (int) new_pad - (int) old_pad);
+		if (err)
+			return err;
+	}
+
+	if (new_pad > 0) {
+		char pad_tlv_buf[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+					0, 0, 0};
+		struct sr6_tlv_t *pad_tlv = (struct sr6_tlv_t *) pad_tlv_buf;
+
+		pad_tlv->type = SR6_TLV_PADDING;
+		pad_tlv->len = new_pad - 2;
+
+		err = bpf_lwt_seg6_store_bytes(skb, pad_off,
+					       (void *)pad_tlv_buf, new_pad);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static __attribute__((always_inline))
+int is_valid_tlv_boundary(struct __sk_buff *skb, struct ip6_srh_t *srh,
+			  uint32_t *tlv_off, uint32_t *pad_size,
+			  uint32_t *pad_off)
+{
+	uint32_t srh_off, cur_off;
+	int offset_valid = 0;
+	int err;
+
+	srh_off = (char *)srh - (char *)(long)skb->data;
+	// cur_off = end of segments, start of possible TLVs
+	cur_off = srh_off + sizeof(*srh) +
+		sizeof(struct ip6_addr_t) * (srh->first_segment + 1);
+
+	*pad_off = 0;
+
+	// we can only go as far as ~10 TLVs due to the BPF max stack size
+	#pragma clang loop unroll(disable)
+	for (int i = 0; i < 100; i++) {
+		struct sr6_tlv_t tlv;
+
+		if (cur_off == *tlv_off)
+			offset_valid = 1;
+
+		if (cur_off >= srh_off + ((srh->hdrlen + 1) << 3))
+			break;
+
+		err = bpf_skb_load_bytes(skb, cur_off, &tlv, sizeof(tlv));
+		if (err)
+			return err;
+
+		if (tlv.type == SR6_TLV_PADDING) {
+			*pad_size = tlv.len + sizeof(tlv);
+			*pad_off = cur_off;
+
+			if (*tlv_off == srh_off) {
+				*tlv_off = cur_off;
+				offset_valid = 1;
+			}
+			break;
+
+		} else if (tlv.type == SR6_TLV_HMAC) {
+			break;
+		}
+
+		cur_off += sizeof(tlv) + tlv.len;
+	} // we reached the padding or HMAC TLVs, or the end of the SRH
+
+	if (*pad_off == 0)
+		*pad_off = cur_off;
+
+	if (*tlv_off == -1)
+		*tlv_off = cur_off;
+	else if (!offset_valid)
+		return -EINVAL;
+
+	return 0;
+}
+
+static __attribute__((always_inline))
+int add_tlv(struct __sk_buff *skb, struct ip6_srh_t *srh, uint32_t tlv_off,
+	    struct sr6_tlv_t *itlv, uint8_t tlv_size)
+{
+	uint32_t srh_off = (char *)srh - (char *)(long)skb->data;
+	uint8_t len_remaining, new_pad;
+	uint32_t pad_off = 0;
+	uint32_t pad_size = 0;
+	uint32_t partial_srh_len;
+	int err;
+
+	if (tlv_off != -1)
+		tlv_off += srh_off;
+
+	if (itlv->type == SR6_TLV_PADDING || itlv->type == SR6_TLV_HMAC)
+		return -EINVAL;
+
+	err = is_valid_tlv_boundary(skb, srh, &tlv_off, &pad_size, &pad_off);
+	if (err)
+		return err;
+
+	err = bpf_lwt_seg6_adjust_srh(skb, tlv_off, sizeof(*itlv) + itlv->len);
+	if (err)
+		return err;
+
+	err = bpf_lwt_seg6_store_bytes(skb, tlv_off, (void *)itlv, tlv_size);
+	if (err)
+		return err;
+
+	// the following can't be moved inside update_tlv_pad because the
+	// bpf verifier has some issues with it
+	pad_off += sizeof(*itlv) + itlv->len;
+	partial_srh_len = pad_off - srh_off;
+	len_remaining = partial_srh_len % 8;
+	new_pad = 8 - len_remaining;
+
+	if (new_pad == 1) // cannot pad for 1 byte only
+		new_pad = 9;
+	else if (new_pad == 8)
+		new_pad = 0;
+
+	return update_tlv_pad(skb, new_pad, pad_size, pad_off);
+}
+
+// Add an Egress TLV fc00::4, add the flag A,
+// and apply End.X action to fc42::1
+SEC("lwt_seg6local")
+int __add_egr_x(struct __sk_buff *skb)
+{
+	unsigned long long hi = 0xfc42000000000000;
+	unsigned long long lo = 0x1;
+	struct ip6_srh_t *srh = get_srh(skb);
+	uint8_t new_flags = SR6_FLAG_ALERT;
+	struct ip6_addr_t addr;
+	int err, offset;
+
+	if (srh == NULL)
+		return BPF_DROP;
+
+	uint8_t tlv[20] = {2, 18, 0, 0, 0xfd, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			   0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x4};
+
+	err = add_tlv(skb, srh, (srh->hdrlen+1) << 3,
+		      (struct sr6_tlv_t *)&tlv, 20);
+	if (err)
+		return BPF_DROP;
+
+	offset = sizeof(struct ip6_t) + offsetof(struct ip6_srh_t, flags);
+	err = bpf_lwt_seg6_store_bytes(skb, offset,
+				       (void *)&new_flags, sizeof(new_flags));
+	if (err)
+		return BPF_DROP;
+
+	addr.lo = htonll(lo);
+	addr.hi = htonll(hi);
+	err = bpf_lwt_seg6_action(skb, SEG6_LOCAL_ACTION_END_X,
+				  (void *)&addr, sizeof(addr));
+	if (err)
+		return BPF_DROP;
+	return BPF_REDIRECT;
+}
+char __license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/test_sysctl_loop1.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <stdint.h>
+#include <string.h>
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+
+#include "bpf_helpers.h"
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+/* tcp_mem sysctl has only 3 ints, but this test is doing TCP_MEM_LOOPS */
+#define TCP_MEM_LOOPS 28  /* because 30 doesn't fit into 512 bytes of stack */
+#define MAX_ULONG_STR_LEN 7
+#define MAX_VALUE_STR_LEN (TCP_MEM_LOOPS * MAX_ULONG_STR_LEN)
+
+static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
+{
+	volatile char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string";
+	unsigned char i;
+	char name[64];
+	int ret;
+
+	memset(name, 0, sizeof(name));
+	ret = bpf_sysctl_get_name(ctx, name, sizeof(name), 0);
+	if (ret < 0 || ret != sizeof(tcp_mem_name) - 1)
+		return 0;
+
+#pragma clang loop unroll(disable)
+	for (i = 0; i < sizeof(tcp_mem_name); ++i)
+		if (name[i] != tcp_mem_name[i])
+			return 0;
+
+	return 1;
+}
+
+SEC("cgroup/sysctl")
+int sysctl_tcp_mem(struct bpf_sysctl *ctx)
+{
+	unsigned long tcp_mem[TCP_MEM_LOOPS] = {};
+	char value[MAX_VALUE_STR_LEN];
+	unsigned char i, off = 0;
+	int ret;
+
+	if (ctx->write)
+		return 0;
+
+	if (!is_tcp_mem(ctx))
+		return 0;
+
+	ret = bpf_sysctl_get_current_value(ctx, value, MAX_VALUE_STR_LEN);
+	if (ret < 0 || ret >= MAX_VALUE_STR_LEN)
+		return 0;
+
+#pragma clang loop unroll(disable)
+	for (i = 0; i < ARRAY_SIZE(tcp_mem); ++i) {
+		ret = bpf_strtoul(value + off, MAX_ULONG_STR_LEN, 0,
+				  tcp_mem + i);
+		if (ret <= 0 || ret > MAX_ULONG_STR_LEN)
+			return 0;
+		off += ret & MAX_ULONG_STR_LEN;
+	}
+
+	return tcp_mem[0] < tcp_mem[1] && tcp_mem[1] < tcp_mem[2];
+}
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/test_sysctl_loop2.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <stdint.h>
+#include <string.h>
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+
+#include "bpf_helpers.h"
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+/* tcp_mem sysctl has only 3 ints, but this test is doing TCP_MEM_LOOPS */
+#define TCP_MEM_LOOPS 20  /* because 30 doesn't fit into 512 bytes of stack */
+#define MAX_ULONG_STR_LEN 7
+#define MAX_VALUE_STR_LEN (TCP_MEM_LOOPS * MAX_ULONG_STR_LEN)
+
+static __attribute__((noinline)) int is_tcp_mem(struct bpf_sysctl *ctx)
+{
+	volatile char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string_to_stress_byte_loop";
+	unsigned char i;
+	char name[64];
+	int ret;
+
+	memset(name, 0, sizeof(name));
+	ret = bpf_sysctl_get_name(ctx, name, sizeof(name), 0);
+	if (ret < 0 || ret != sizeof(tcp_mem_name) - 1)
+		return 0;
+
+#pragma clang loop unroll(disable)
+	for (i = 0; i < sizeof(tcp_mem_name); ++i)
+		if (name[i] != tcp_mem_name[i])
+			return 0;
+
+	return 1;
+}
+
+
+SEC("cgroup/sysctl")
+int sysctl_tcp_mem(struct bpf_sysctl *ctx)
+{
+	unsigned long tcp_mem[TCP_MEM_LOOPS] = {};
+	char value[MAX_VALUE_STR_LEN];
+	unsigned char i, off = 0;
+	int ret;
+
+	if (ctx->write)
+		return 0;
+
+	if (!is_tcp_mem(ctx))
+		return 0;
+
+	ret = bpf_sysctl_get_current_value(ctx, value, MAX_VALUE_STR_LEN);
+	if (ret < 0 || ret >= MAX_VALUE_STR_LEN)
+		return 0;
+
+#pragma clang loop unroll(disable)
+	for (i = 0; i < ARRAY_SIZE(tcp_mem); ++i) {
+		ret = bpf_strtoul(value + off, MAX_ULONG_STR_LEN, 0,
+				  tcp_mem + i);
+		if (ret <= 0 || ret > MAX_ULONG_STR_LEN)
+			return 0;
+		off += ret & MAX_ULONG_STR_LEN;
+	}
+
+	return tcp_mem[0] < tcp_mem[1] && tcp_mem[1] < tcp_mem[2];
+}
+
+char _license[] SEC("license") = "GPL";

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

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <stddef.h>
+#include <string.h>
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/in.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
+#include <linux/pkt_cls.h>
+#include <sys/socket.h>
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+#include "test_iptunnel_common.h"
+
+int _version SEC("version") = 1;
+
+struct bpf_map_def SEC("maps") rxcnt = {
+	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u64),
+	.max_entries = 256,
+};
+
+struct bpf_map_def SEC("maps") vip2tnl = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(struct vip),
+	.value_size = sizeof(struct iptnl_info),
+	.max_entries = MAX_IPTNL_ENTRIES,
+};
+
+static __always_inline void count_tx(__u32 protocol)
+{
+	__u64 *rxcnt_count;
+
+	rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
+	if (rxcnt_count)
+		*rxcnt_count += 1;
+}
+
+static __always_inline int get_dport(void *trans_data, void *data_end,
+				     __u8 protocol)
+{
+	struct tcphdr *th;
+	struct udphdr *uh;
+
+	switch (protocol) {
+	case IPPROTO_TCP:
+		th = (struct tcphdr *)trans_data;
+		if (th + 1 > data_end)
+			return -1;
+		return th->dest;
+	case IPPROTO_UDP:
+		uh = (struct udphdr *)trans_data;
+		if (uh + 1 > data_end)
+			return -1;
+		return uh->dest;
+	default:
+		return 0;
+	}
+}
+
+static __always_inline void set_ethhdr(struct ethhdr *new_eth,
+				       const struct ethhdr *old_eth,
+				       const struct iptnl_info *tnl,
+				       __be16 h_proto)
+{
+	memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
+	memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
+	new_eth->h_proto = h_proto;
+}
+
+static __always_inline int handle_ipv4(struct xdp_md *xdp)
+{
+	void *data_end = (void *)(long)xdp->data_end;
+	void *data = (void *)(long)xdp->data;
+	struct iptnl_info *tnl;
+	struct ethhdr *new_eth;
+	struct ethhdr *old_eth;
+	struct iphdr *iph = data + sizeof(struct ethhdr);
+	__u16 *next_iph;
+	__u16 payload_len;
+	struct vip vip = {};
+	int dport;
+	__u32 csum = 0;
+	int i;
+
+	if (iph + 1 > data_end)
+		return XDP_DROP;
+
+	dport = get_dport(iph + 1, data_end, iph->protocol);
+	if (dport == -1)
+		return XDP_DROP;
+
+	vip.protocol = iph->protocol;
+	vip.family = AF_INET;
+	vip.daddr.v4 = iph->daddr;
+	vip.dport = dport;
+	payload_len = bpf_ntohs(iph->tot_len);
+
+	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
+	/* It only does v4-in-v4 */
+	if (!tnl || tnl->family != AF_INET)
+		return XDP_PASS;
+
+	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
+		return XDP_DROP;
+
+	data = (void *)(long)xdp->data;
+	data_end = (void *)(long)xdp->data_end;
+
+	new_eth = data;
+	iph = data + sizeof(*new_eth);
+	old_eth = data + sizeof(*iph);
+
+	if (new_eth + 1 > data_end ||
+	    old_eth + 1 > data_end ||
+	    iph + 1 > data_end)
+		return XDP_DROP;
+
+	set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
+
+	iph->version = 4;
+	iph->ihl = sizeof(*iph) >> 2;
+	iph->frag_off =	0;
+	iph->protocol = IPPROTO_IPIP;
+	iph->check = 0;
+	iph->tos = 0;
+	iph->tot_len = bpf_htons(payload_len + sizeof(*iph));
+	iph->daddr = tnl->daddr.v4;
+	iph->saddr = tnl->saddr.v4;
+	iph->ttl = 8;
+
+	next_iph = (__u16 *)iph;
+#pragma clang loop unroll(disable)
+	for (i = 0; i < sizeof(*iph) >> 1; i++)
+		csum += *next_iph++;
+
+	iph->check = ~((csum & 0xffff) + (csum >> 16));
+
+	count_tx(vip.protocol);
+
+	return XDP_TX;
+}
+
+static __always_inline int handle_ipv6(struct xdp_md *xdp)
+{
+	void *data_end = (void *)(long)xdp->data_end;
+	void *data = (void *)(long)xdp->data;
+	struct iptnl_info *tnl;
+	struct ethhdr *new_eth;
+	struct ethhdr *old_eth;
+	struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
+	__u16 payload_len;
+	struct vip vip = {};
+	int dport;
+
+	if (ip6h + 1 > data_end)
+		return XDP_DROP;
+
+	dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
+	if (dport == -1)
+		return XDP_DROP;
+
+	vip.protocol = ip6h->nexthdr;
+	vip.family = AF_INET6;
+	memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
+	vip.dport = dport;
+	payload_len = ip6h->payload_len;
+
+	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
+	/* It only does v6-in-v6 */
+	if (!tnl || tnl->family != AF_INET6)
+		return XDP_PASS;
+
+	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
+		return XDP_DROP;
+
+	data = (void *)(long)xdp->data;
+	data_end = (void *)(long)xdp->data_end;
+
+	new_eth = data;
+	ip6h = data + sizeof(*new_eth);
+	old_eth = data + sizeof(*ip6h);
+
+	if (new_eth + 1 > data_end || old_eth + 1 > data_end ||
+	    ip6h + 1 > data_end)
+		return XDP_DROP;
+
+	set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
+
+	ip6h->version = 6;
+	ip6h->priority = 0;
+	memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
+	ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + sizeof(*ip6h));
+	ip6h->nexthdr = IPPROTO_IPV6;
+	ip6h->hop_limit = 8;
+	memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
+	memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
+
+	count_tx(vip.protocol);
+
+	return XDP_TX;
+}
+
+SEC("xdp_tx_iptunnel")
+int _xdp_tx_iptunnel(struct xdp_md *xdp)
+{
+	void *data_end = (void *)(long)xdp->data_end;
+	void *data = (void *)(long)xdp->data;
+	struct ethhdr *eth = data;
+	__u16 h_proto;
+
+	if (eth + 1 > data_end)
+		return XDP_DROP;
+
+	h_proto = eth->h_proto;
+
+	if (h_proto == bpf_htons(ETH_P_IP))
+		return handle_ipv4(xdp);
+	else if (h_proto == bpf_htons(ETH_P_IPV6))
+
+		return handle_ipv6(xdp);
+	else
+		return XDP_DROP;
+}
+
+char _license[] SEC("license") = "GPL";