diff mbox series

[bpf-next,v5,4/5] lib/bpf: Assign cookies to links in libbpf.

Message ID 20220412165555.4146407-5-kuifeng@fb.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Attach a cookie to a tracing program. | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-1 fail Logs for Kernel LATEST on ubuntu-latest + selftests
bpf/vmtest-bpf-next-VM_Test-2 fail Logs for Kernel LATEST on z15 + selftests
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 6 maintainers not CCed: songliubraving@fb.com netdev@vger.kernel.org kafai@fb.com yhs@fb.com john.fastabend@gmail.com kpsingh@kernel.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning CHECK: Please use a blank line after function/struct/union/enum declarations WARNING: line length of 82 exceeds 80 columns WARNING: line length of 84 exceeds 80 columns WARNING: line length of 92 exceeds 80 columns WARNING: line length of 98 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 48 this patch: 48
netdev/source_inline success Was 0 now: 0

Commit Message

Kui-Feng Lee April 12, 2022, 4:55 p.m. UTC 
Add a cookie field to the attributes of bpf_link_create().
Add bpf_program__attach_trace_opts() to attach a cookie to a link.

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
---
 tools/lib/bpf/bpf.c      |  7 +++++++
 tools/lib/bpf/bpf.h      |  3 +++
 tools/lib/bpf/libbpf.c   | 33 +++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h   | 12 ++++++++++++
 tools/lib/bpf/libbpf.map |  1 +
 5 files changed, 56 insertions(+)

Comments

Andrii Nakryiko April 13, 2022, 3:14 a.m. UTC | #1 
On Tue, Apr 12, 2022 at 9:56 AM Kui-Feng Lee <kuifeng@fb.com> wrote:
>
> Add a cookie field to the attributes of bpf_link_create().
> Add bpf_program__attach_trace_opts() to attach a cookie to a link.
>
> Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
> ---

Please stick to "libbpf: " prefix for patch subject, we don't use "lib/bpf: "

>  tools/lib/bpf/bpf.c      |  7 +++++++
>  tools/lib/bpf/bpf.h      |  3 +++
>  tools/lib/bpf/libbpf.c   | 33 +++++++++++++++++++++++++++++++++
>  tools/lib/bpf/libbpf.h   | 12 ++++++++++++
>  tools/lib/bpf/libbpf.map |  1 +
>  5 files changed, 56 insertions(+)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index cf27251adb92..c2454979c3c4 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -863,6 +863,13 @@ int bpf_link_create(int prog_fd, int target_fd,
>                 if (!OPTS_ZEROED(opts, kprobe_multi))
>                         return libbpf_err(-EINVAL);
>                 break;
> +       case BPF_TRACE_FENTRY:
> +       case BPF_TRACE_FEXIT:
> +       case BPF_MODIFY_RETURN:
> +               attr.link_create.tracing.bpf_cookie = OPTS_GET(opts, tracing.bpf_cookie, 0);
> +               if (!OPTS_ZEROED(opts, tracing))
> +                       return libbpf_err(-EINVAL);
> +               break;
>         default:
>                 if (!OPTS_ZEROED(opts, flags))
>                         return libbpf_err(-EINVAL);
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index f4b4afb6d4ba..4cdbabcccefc 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -410,6 +410,9 @@ struct bpf_link_create_opts {
>         __u32 iter_info_len;
>         __u32 target_btf_id;
>         union {
> +               struct {
> +                       __u64 bpf_cookie;
> +               } tracing;
>                 struct {
>                         __u64 bpf_cookie;
>                 } perf_event;
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index bf4f7ac54ebf..8586e1efd780 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -11262,6 +11262,39 @@ struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
>         return bpf_program__attach_btf_id(prog);
>  }
>
> +struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
> +                                               const struct bpf_trace_opts *opts)
> +{
> +       char errmsg[STRERR_BUFSIZE];
> +       struct bpf_link *link;
> +       int prog_fd, pfd;
> +

unnecessary empty line, LIBBPF_OPTS is a variable declaration, so keep
it together with other variables

> +       LIBBPF_OPTS(bpf_link_create_opts, link_opts);
> +
> +       prog_fd = bpf_program__fd(prog);
> +       if (prog_fd < 0) {
> +               pr_warn("prog '%s': can't attach before loaded\n", prog->name);
> +               return libbpf_err_ptr(-EINVAL);
> +       }
> +
> +       link = calloc(1, sizeof(*link));
> +       if (!link)
> +               return libbpf_err_ptr(-ENOMEM);
> +       link->detach = &bpf_link__detach_fd;
> +
> +       link_opts.tracing.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
> +       pfd = bpf_link_create(prog_fd, 0, prog->expected_attach_type, &link_opts);

so this won't work on old kernels that don't support creating
fentry/fexit links through LINK_CREATE. Let's for now check if
bpf_cookie is zero, then redirect to bpf_program__attach_trace().
Ideally we should perform feature detection of ability to use
LINK_CREATE to attach fentry and have a unified single
bpf_program__attach_btf_id() implementation that will handle all that
internally

> +       if (pfd < 0) {
> +               pfd = -errno;
> +               free(link);
> +               pr_warn("prog '%s': failed to attach: %s\n",
> +                       prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
> +               return libbpf_err_ptr(pfd);
> +       }
> +       link->fd = pfd;
> +       return (struct bpf_link *)link;
> +}
> +
>  struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
>  {
>         return bpf_program__attach_btf_id(prog);
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 63d66f1adf1a..e0dd3f9a5aca 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -563,8 +563,20 @@ bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
>  LIBBPF_API struct bpf_link *
>  bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
>                                    const char *tp_name);
> +
> +struct bpf_trace_opts {
> +       /* size of this struct, for forward/backward compatibility */
> +       size_t sz;
> +       /* custom user-provided value fetchable through bpf_get_attach_cookie() */
> +       __u64 bpf_cookie;
> +};
> +#define bpf_trace_opts__last_field bpf_cookie
> +
>  LIBBPF_API struct bpf_link *
>  bpf_program__attach_trace(const struct bpf_program *prog);
> +LIBBPF_API struct bpf_link *
> +bpf_program__attach_trace_opts(const struct bpf_program *prog, const struct bpf_trace_opts *opts);
> +
>  LIBBPF_API struct bpf_link *
>  bpf_program__attach_lsm(const struct bpf_program *prog);
>  LIBBPF_API struct bpf_link *
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 82f6d62176dd..9235da802e31 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -424,6 +424,7 @@ LIBBPF_0.6.0 {
>  LIBBPF_0.7.0 {
>         global:
>                 bpf_btf_load;
> +               bpf_program__attach_trace_opts;

this should go into LIBBPF_0.8.0

>                 bpf_program__expected_attach_type;
>                 bpf_program__log_buf;
>                 bpf_program__log_level;
> --
> 2.30.2
>
diff mbox series

Patch

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index cf27251adb92..c2454979c3c4 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -863,6 +863,13 @@  int bpf_link_create(int prog_fd, int target_fd,
 		if (!OPTS_ZEROED(opts, kprobe_multi))
 			return libbpf_err(-EINVAL);
 		break;
+	case BPF_TRACE_FENTRY:
+	case BPF_TRACE_FEXIT:
+	case BPF_MODIFY_RETURN:
+		attr.link_create.tracing.bpf_cookie = OPTS_GET(opts, tracing.bpf_cookie, 0);
+		if (!OPTS_ZEROED(opts, tracing))
+			return libbpf_err(-EINVAL);
+		break;
 	default:
 		if (!OPTS_ZEROED(opts, flags))
 			return libbpf_err(-EINVAL);
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index f4b4afb6d4ba..4cdbabcccefc 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -410,6 +410,9 @@  struct bpf_link_create_opts {
 	__u32 iter_info_len;
 	__u32 target_btf_id;
 	union {
+		struct {
+			__u64 bpf_cookie;
+		} tracing;
 		struct {
 			__u64 bpf_cookie;
 		} perf_event;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index bf4f7ac54ebf..8586e1efd780 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11262,6 +11262,39 @@  struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
 	return bpf_program__attach_btf_id(prog);
 }
 
+struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
+						const struct bpf_trace_opts *opts)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, pfd;
+
+	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	link_opts.tracing.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+	pfd = bpf_link_create(prog_fd, 0, prog->expected_attach_type, &link_opts);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link->fd = pfd;
+	return (struct bpf_link *)link;
+}
+
 struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
 {
 	return bpf_program__attach_btf_id(prog);
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 63d66f1adf1a..e0dd3f9a5aca 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -563,8 +563,20 @@  bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
 LIBBPF_API struct bpf_link *
 bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
 				   const char *tp_name);
+
+struct bpf_trace_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 bpf_cookie;
+};
+#define bpf_trace_opts__last_field bpf_cookie
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_trace(const struct bpf_program *prog);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace_opts(const struct bpf_program *prog, const struct bpf_trace_opts *opts);
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_lsm(const struct bpf_program *prog);
 LIBBPF_API struct bpf_link *
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 82f6d62176dd..9235da802e31 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -424,6 +424,7 @@  LIBBPF_0.6.0 {
 LIBBPF_0.7.0 {
 	global:
 		bpf_btf_load;
+		bpf_program__attach_trace_opts;
 		bpf_program__expected_attach_type;
 		bpf_program__log_buf;
 		bpf_program__log_level;