selftests/bpf: Add tests for bpf_dynptr_copy

Add XDP setup type for dynptr tests, enabling testing for
non-contiguous buffer.
Add 2 tests:
 - test_dynptr_copy - verify correctness for the fast (contiguous
 buffer) code path.
 - test_dynptr_copy_xdp - verifies code paths that handle
 non-contiguous buffer.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250226183201.332713-4-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index b614a5272dfd6486e287181270a0bcf63f638344..e29cc16124c2dfc57d94067992fdb6246f0f650e 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -10,6 +10,7 @@ enum test_setup_type {
        SETUP_SYSCALL_SLEEP,
        SETUP_SKB_PROG,
        SETUP_SKB_PROG_TP,
+       SETUP_XDP_PROG,
 };
 
 static struct {
@@ -18,6 +19,8 @@ static struct {
 } success_tests[] = {
        {"test_read_write", SETUP_SYSCALL_SLEEP},
        {"test_dynptr_data", SETUP_SYSCALL_SLEEP},
+       {"test_dynptr_copy", SETUP_SYSCALL_SLEEP},
+       {"test_dynptr_copy_xdp", SETUP_XDP_PROG},
        {"test_ringbuf", SETUP_SYSCALL_SLEEP},
        {"test_skb_readonly", SETUP_SKB_PROG},
        {"test_dynptr_skb_data", SETUP_SKB_PROG},
@@ -120,6 +123,24 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
 
                break;
        }
+       case SETUP_XDP_PROG:
+       {
+               char data[5000];
+               int err, prog_fd;
+               LIBBPF_OPTS(bpf_test_run_opts, opts,
+                           .data_in = &data,
+                           .data_size_in = sizeof(data),
+                           .repeat = 1,
+               );
+
+               prog_fd = bpf_program__fd(prog);
+               err = bpf_prog_test_run_opts(prog_fd, &opts);
+
+               if (!ASSERT_OK(err, "test_run"))
+                       goto cleanup;
+
+               break;
+       }
        }
 
        ASSERT_EQ(skel->bss->err, 0, "err");

diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
index bfcc85686cf046361b451f97f4cd310a6ccdb1ed..e1fba28e4a868a750fc7a77e2c3b6db231aa190d 100644 (file)
--- a/tools/testing/selftests/bpf/progs/dynptr_success.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
@@ -1,20 +1,19 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2022 Facebook */
 
+#include <vmlinux.h>
 #include <string.h>
 #include <stdbool.h>
-#include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include "bpf_misc.h"
-#include "bpf_kfuncs.h"
 #include "errno.h"
 
 char _license[] SEC("license") = "GPL";
 
 int pid, err, val;
 
-struct sample {
+struct ringbuf_sample {
        int pid;
        int seq;
        long value;
@@ -121,7 +120,7 @@ int test_dynptr_data(void *ctx)
 
 static int ringbuf_callback(__u32 index, void *data)
 {
-       struct sample *sample;
+       struct ringbuf_sample *sample;
 
        struct bpf_dynptr *ptr = (struct bpf_dynptr *)data;
 
@@ -138,7 +137,7 @@ SEC("?tp/syscalls/sys_enter_nanosleep")
 int test_ringbuf(void *ctx)
 {
        struct bpf_dynptr ptr;
-       struct sample *sample;
+       struct ringbuf_sample *sample;
 
        if (bpf_get_current_pid_tgid() >> 32 != pid)
                return 0;
@@ -567,3 +566,117 @@ int BPF_PROG(test_dynptr_skb_tp_btf, void *skb, void *location)
 
        return 1;
 }
+
+static inline int bpf_memcmp(const char *a, const char *b, u32 size)
+{
+       int i;
+
+       bpf_for(i, 0, size) {
+               if (a[i] != b[i])
+                       return a[i] < b[i] ? -1 : 1;
+       }
+       return 0;
+}
+
+SEC("?tp/syscalls/sys_enter_nanosleep")
+int test_dynptr_copy(void *ctx)
+{
+       char data[] = "hello there, world!!";
+       char buf[32] = {'\0'};
+       __u32 sz = sizeof(data);
+       struct bpf_dynptr src, dst;
+
+       bpf_ringbuf_reserve_dynptr(&ringbuf, sz, 0, &src);
+       bpf_ringbuf_reserve_dynptr(&ringbuf, sz, 0, &dst);
+
+       /* Test basic case of copying contiguous memory backed dynptrs */
+       err = bpf_dynptr_write(&src, 0, data, sz, 0);
+       err = err ?: bpf_dynptr_copy(&dst, 0, &src, 0, sz);
+       err = err ?: bpf_dynptr_read(buf, sz, &dst, 0, 0);
+       err = err ?: bpf_memcmp(data, buf, sz);
+
+       /* Test that offsets are handled correctly */
+       err = err ?: bpf_dynptr_copy(&dst, 3, &src, 5, sz - 5);
+       err = err ?: bpf_dynptr_read(buf, sz - 5, &dst, 3, 0);
+       err = err ?: bpf_memcmp(data + 5, buf, sz - 5);
+
+       bpf_ringbuf_discard_dynptr(&src, 0);
+       bpf_ringbuf_discard_dynptr(&dst, 0);
+       return 0;
+}
+
+SEC("xdp")
+int test_dynptr_copy_xdp(struct xdp_md *xdp)
+{
+       struct bpf_dynptr ptr_buf, ptr_xdp;
+       char data[] = "qwertyuiopasdfghjkl";
+       char buf[32] = {'\0'};
+       __u32 len = sizeof(data);
+       int i, chunks = 200;
+
+       /* ptr_xdp is backed by non-contiguous memory */
+       bpf_dynptr_from_xdp(xdp, 0, &ptr_xdp);
+       bpf_ringbuf_reserve_dynptr(&ringbuf, len * chunks, 0, &ptr_buf);
+
+       /* Destination dynptr is backed by non-contiguous memory */
+       bpf_for(i, 0, chunks) {
+               err = bpf_dynptr_write(&ptr_buf, i * len, data, len, 0);
+               if (err)
+                       goto out;
+       }
+
+       err = bpf_dynptr_copy(&ptr_xdp, 0, &ptr_buf, 0, len * chunks);
+       if (err)
+               goto out;
+
+       bpf_for(i, 0, chunks) {
+               __builtin_memset(buf, 0, sizeof(buf));
+               err = bpf_dynptr_read(&buf, len, &ptr_xdp, i * len, 0);
+               if (err)
+                       goto out;
+               if (bpf_memcmp(data, buf, len) != 0)
+                       goto out;
+       }
+
+       /* Source dynptr is backed by non-contiguous memory */
+       __builtin_memset(buf, 0, sizeof(buf));
+       bpf_for(i, 0, chunks) {
+               err = bpf_dynptr_write(&ptr_buf, i * len, buf, len, 0);
+               if (err)
+                       goto out;
+       }
+
+       err = bpf_dynptr_copy(&ptr_buf, 0, &ptr_xdp, 0, len * chunks);
+       if (err)
+               goto out;
+
+       bpf_for(i, 0, chunks) {
+               __builtin_memset(buf, 0, sizeof(buf));
+               err = bpf_dynptr_read(&buf, len, &ptr_buf, i * len, 0);
+               if (err)
+                       goto out;
+               if (bpf_memcmp(data, buf, len) != 0)
+                       goto out;
+       }
+
+       /* Both source and destination dynptrs are backed by non-contiguous memory */
+       err = bpf_dynptr_copy(&ptr_xdp, 2, &ptr_xdp, len, len * (chunks - 1));
+       if (err)
+               goto out;
+
+       bpf_for(i, 0, chunks - 1) {
+               __builtin_memset(buf, 0, sizeof(buf));
+               err = bpf_dynptr_read(&buf, len, &ptr_xdp, 2 + i * len, 0);
+               if (err)
+                       goto out;
+               if (bpf_memcmp(data, buf, len) != 0)
+                       goto out;
+       }
+
+       if (bpf_dynptr_copy(&ptr_xdp, 2000, &ptr_xdp, 0, len * chunks) != -E2BIG)
+               err = 1;
+
+out:
+       bpf_ringbuf_discard_dynptr(&ptr_buf, 0);
+       return XDP_DROP;
+}