Hi, Andrii!
On Tue, Mar 2, 2021 at 7:08 AM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Mon, Mar 1, 2021 at 1:02 AM Yauheni Kaliuta
> <yauheni.kaliuta@xxxxxxxxxx> wrote:
> >
> > Hi!
> >
> > Bunch of bpf selftests actually depends of page size and has it
> > hardcoded to 4K. That causes failures if page shift is configured
> > to values other than 12. It looks as a known issue since for the
> > userspace parts sysconf(_SC_PAGE_SIZE) is used, but what would be
> > the correct way to export it to bpf programs?
> >
>
> Given PAGE_SIZE and PAGE_SHIFT are just #defines, the only way seems
> to be to pass it from the user-space as a read-only variable.
>
I could not find a good example to attach to cgroup. Here is the
draft, could you point me to right direction?
diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
index d5b44b135c00..7932236a021e 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
@@ -1,8 +1,8 @@
// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include "cgroup_helpers.h"
-
#include <linux/tcp.h>
+#include "sockopt_sk.skel.h"
#ifndef SOL_TCP
#define SOL_TCP IPPROTO_TCP
@@ -191,60 +191,33 @@ static int getsetsockopt(void)
return -1;
}
-static int prog_attach(struct bpf_object *obj, int cgroup_fd, const
char *title)
-{
- enum bpf_attach_type attach_type;
- enum bpf_prog_type prog_type;
- struct bpf_program *prog;
- int err;
-
- err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
- if (err) {
- log_err("Failed to deduct types for %s BPF program", title);
- return -1;
- }
-
- prog = bpf_object__find_program_by_title(obj, title);
- if (!prog) {
- log_err("Failed to find %s BPF program", title);
- return -1;
- }
-
- err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd,
- attach_type, 0);
- if (err) {
- log_err("Failed to attach %s BPF program", title);
- return -1;
- }
-
- return 0;
-}
-
static void run_test(int cgroup_fd)
{
- struct bpf_prog_load_attr attr = {
- .file = "./sockopt_sk.o",
- };
- struct bpf_object *obj;
- int ignored;
+ struct sockopt_sk *skel;
+ int prog_fd;
+ int duration = 0;
int err;
- err = bpf_prog_load_xattr(&attr, &obj, &ignored);
- if (CHECK_FAIL(err))
- return;
+ skel = sockopt_sk__open_and_load();
+ if (CHECK(!skel, "skel_load", "sockopt_sk skeleton failed\n"))
+ goto cleanup;
+
+ skel->bss->page_size = getpagesize();
- err = prog_attach(obj, cgroup_fd, "cgroup/getsockopt");
- if (CHECK_FAIL(err))
- goto close_bpf_object;
+ prog_fd = bpf_program__fd(skel->progs._getsockopt);
+ err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_GETSOCKOPT, 0);
+ if (CHECK(err, "attach", "getsockopt attach failed: %d\n", err))
+ goto cleanup;
- err = prog_attach(obj, cgroup_fd, "cgroup/setsockopt");
- if (CHECK_FAIL(err))
- goto close_bpf_object;
+ prog_fd = bpf_program__fd(skel->progs._setsockopt);
+ err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SETSOCKOPT, 0);
+ if (CHECK(err, "attach", "setsockopt attach failed: %d\n", err))
+ goto cleanup;
CHECK_FAIL(getsetsockopt());
-close_bpf_object:
- bpf_object__close(obj);
+cleanup:
+ sockopt_sk__destroy(skel);
}
void test_sockopt_sk(void)
diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c
b/tools/testing/selftests/bpf/progs/sockopt_sk.c
index d3597f81e6e9..f8b051589681 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
@@ -8,9 +8,7 @@
char _license[] SEC("license") = "GPL";
__u32 _version SEC("version") = 1;
-#ifndef PAGE_SIZE
-#define PAGE_SIZE 4096
-#endif
+int page_size; /* userspace should set it */
#ifndef SOL_TCP
#define SOL_TCP IPPROTO_TCP
@@ -41,7 +39,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
* let next BPF program in the cgroup chain or kernel
* handle it.
*/
- ctx->optlen = 0; /* bypass optval>PAGE_SIZE */
+ ctx->optlen = 0; /* bypass optval>page_size */
return 1;
}
@@ -86,11 +84,11 @@ int _getsockopt(struct bpf_sockopt *ctx)
optval[0] = 0x55;
ctx->optlen = 1;
- /* Userspace buffer is PAGE_SIZE * 2, but BPF
- * program can only see the first PAGE_SIZE
+ /* Userspace buffer is page_size * 2, but BPF
+ * program can only see the first page_size
* bytes of data.
*/
- if (optval_end - optval != PAGE_SIZE)
+ if (optval_end - optval != page_size)
return 0; /* EPERM, unexpected data size */
return 1;
@@ -131,7 +129,7 @@ int _setsockopt(struct bpf_sockopt *ctx)
* let next BPF program in the cgroup chain or kernel
* handle it.
*/
- ctx->optlen = 0; /* bypass optval>PAGE_SIZE */
+ ctx->optlen = 0; /* bypass optval>page_size */
return 1;
}
@@ -160,8 +158,8 @@ int _setsockopt(struct bpf_sockopt *ctx)
}
if (ctx->level == SOL_IP && ctx->optname == IP_FREEBIND) {
- /* Original optlen is larger than PAGE_SIZE. */
- if (ctx->optlen != PAGE_SIZE * 2)
+ /* Original optlen is larger than page_size. */
+ if (ctx->optlen != page_size * 2)
return 0; /* EPERM, unexpected data size */
if (optval + 1 > optval_end)
@@ -171,11 +169,11 @@ int _setsockopt(struct bpf_sockopt *ctx)
optval[0] = 0;
ctx->optlen = 1;
- /* Usepace buffer is PAGE_SIZE * 2, but BPF
- * program can only see the first PAGE_SIZE
+ /* Usepace buffer is page_size * 2, but BPF
+ * program can only see the first page_size
* bytes of data.
*/
- if (optval_end - optval != PAGE_SIZE)
+ if (optval_end - optval != page_size)
return 0; /* EPERM, unexpected data size */
return 1;
--
WBR, Yauheni
