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Message-Id: <20210929235910.1765396-9-jevburton.kernel@gmail.com>
Date: Wed, 29 Sep 2021 23:59:05 +0000
From: Joe Burton <jevburton.kernel@...il.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>
Cc: Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Petar Penkov <ppenkov@...gle.com>,
Stanislav Fomichev <sdf@...gle.com>,
Hao Luo <haoluo@...gle.com>, netdev@...r.kernel.org,
bpf@...r.kernel.org, Joe Burton <jevburton@...gle.com>
Subject: [RFC PATCH v2 08/13] libbpf: Support BPF_TRACE_MAP
From: Joe Burton <jevburton@...gle.com>
Programs may be now loaded with libbpf. Sections with the prefix
"map_trace/" will use the new attach type.
Signed-off-by: Joe Burton <jevburton@...gle.com>
---
tools/include/uapi/linux/bpf.h | 22 ++++++
tools/lib/bpf/bpf.c | 13 ++--
tools/lib/bpf/bpf.h | 4 +-
tools/lib/bpf/libbpf.c | 118 +++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 11 +++
tools/lib/bpf/libbpf.map | 1 +
6 files changed, 163 insertions(+), 6 deletions(-)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 6fc59d61937a..3d5d3dafc066 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -93,6 +93,20 @@ union bpf_iter_link_info {
} map;
};
+enum bpf_map_trace_type {
+ BPF_MAP_TRACE_UPDATE_ELEM = 0,
+ BPF_MAP_TRACE_DELETE_ELEM = 1,
+
+ MAX_BPF_MAP_TRACE_TYPE,
+};
+
+struct bpf_map_trace_link_info {
+ __u32 map_fd;
+ enum bpf_map_trace_type trace_type;
+};
+
+#define BPF_MAP_TRACE_FUNC(trace_type) "bpf_map_trace__" #trace_type
+
/* BPF syscall commands, see bpf(2) man-page for more details. */
/**
* DOC: eBPF Syscall Preamble
@@ -994,6 +1008,7 @@ enum bpf_attach_type {
BPF_SK_REUSEPORT_SELECT,
BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
BPF_PERF_EVENT,
+ BPF_TRACE_MAP,
__MAX_BPF_ATTACH_TYPE
};
@@ -1008,6 +1023,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_NETNS = 5,
BPF_LINK_TYPE_XDP = 6,
BPF_LINK_TYPE_PERF_EVENT = 7,
+ BPF_LINK_TYPE_MAP_TRACE = 8,
MAX_BPF_LINK_TYPE,
};
@@ -1455,6 +1471,12 @@ union bpf_attr {
*/
__u64 bpf_cookie;
} perf_event;
+ struct {
+ /* extra bpf_map_trace_link_info */
+ __aligned_u64 map_trace_info;
+ /* map_trace_info length */
+ __u32 map_trace_info_len;
+ };
};
} link_create;
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 2401fad090c5..e18ddd362052 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -674,7 +674,7 @@ int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
const struct bpf_link_create_opts *opts)
{
- __u32 target_btf_id, iter_info_len;
+ __u32 target_btf_id, iter_info_len, map_trace_info_len;
union bpf_attr attr;
int fd;
@@ -682,13 +682,12 @@ int bpf_link_create(int prog_fd, int target_fd,
return libbpf_err(-EINVAL);
iter_info_len = OPTS_GET(opts, iter_info_len, 0);
+ map_trace_info_len = OPTS_GET(opts, map_trace_info_len, 0);
target_btf_id = OPTS_GET(opts, target_btf_id, 0);
/* validate we don't have unexpected combinations of non-zero fields */
- if (iter_info_len || target_btf_id) {
- if (iter_info_len && target_btf_id)
- return libbpf_err(-EINVAL);
- if (!OPTS_ZEROED(opts, target_btf_id))
+ if (iter_info_len || map_trace_info_len || target_btf_id) {
+ if ((iter_info_len || map_trace_info_len) && target_btf_id)
return libbpf_err(-EINVAL);
}
@@ -713,6 +712,10 @@ int bpf_link_create(int prog_fd, int target_fd,
if (!OPTS_ZEROED(opts, perf_event))
return libbpf_err(-EINVAL);
break;
+ case BPF_TRACE_MAP:
+ attr.link_create.map_trace_info = ptr_to_u64(OPTS_GET(opts, map_trace_info, (void *)0));
+ attr.link_create.map_trace_info_len = map_trace_info_len;
+ 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 6fffb3cdf39b..deb276ad489f 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -183,8 +183,10 @@ struct bpf_link_create_opts {
} perf_event;
};
size_t :0;
+ struct bpf_map_trace_link_info *map_trace_info;
+ __u32 map_trace_info_len;
};
-#define bpf_link_create_opts__last_field perf_event
+#define bpf_link_create_opts__last_field map_trace_info_len
LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1c859b32968d..a82126c0b969 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -7987,6 +7987,7 @@ static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cooki
static struct bpf_link *attach_trace(const struct bpf_program *prog, long cookie);
static struct bpf_link *attach_lsm(const struct bpf_program *prog, long cookie);
static struct bpf_link *attach_iter(const struct bpf_program *prog, long cookie);
+static struct bpf_link *attach_map_trace(const struct bpf_program *prog, long cookie);
static const struct bpf_sec_def section_defs[] = {
SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE | SEC_SLOPPY_PFX),
@@ -8014,6 +8015,7 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("lsm/", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
SEC_DEF("lsm.s/", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
SEC_DEF("iter/", TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
+ SEC_DEF("map_trace/", TRACING, BPF_TRACE_MAP, SEC_ATTACH_BTF, attach_map_trace),
SEC_DEF("syscall", SYSCALL, 0, SEC_SLEEPABLE),
SEC_DEF("xdp_devmap/", XDP, BPF_XDP_DEVMAP, SEC_ATTACHABLE),
SEC_DEF("xdp_cpumap/", XDP, BPF_XDP_CPUMAP, SEC_ATTACHABLE),
@@ -8311,6 +8313,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
#define BTF_TRACE_PREFIX "btf_trace_"
#define BTF_LSM_PREFIX "bpf_lsm_"
#define BTF_ITER_PREFIX "bpf_iter_"
+#define BTF_MAP_TRACE_PREFIX "bpf_map_trace__BPF_MAP_TRACE_"
#define BTF_MAX_NAME_SIZE 128
void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
@@ -8329,6 +8332,10 @@ void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
*prefix = BTF_ITER_PREFIX;
*kind = BTF_KIND_FUNC;
break;
+ case BPF_TRACE_MAP:
+ *prefix = BTF_MAP_TRACE_PREFIX;
+ *kind = BTF_KIND_FUNC;
+ break;
default:
*prefix = "";
*kind = BTF_KIND_FUNC;
@@ -8464,6 +8471,15 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attac
__u32 attach_prog_fd = prog->attach_prog_fd;
int err = 0;
+ if (attach_type == BPF_TRACE_MAP) {
+ while (*attach_name && *attach_name != '/')
+ ++attach_name;
+ if (!*attach_name || !*(++attach_name)) {
+ pr_warn("failed to parse trace type from ELF section name '%s'\n", prog->sec_name);
+ return -EINVAL;
+ }
+ }
+
/* BPF program's BTF ID */
if (attach_prog_fd) {
err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
@@ -9951,6 +9967,108 @@ static struct bpf_link *attach_iter(const struct bpf_program *prog, long cookie)
return bpf_program__attach_iter(prog, NULL);
}
+struct bpf_link *
+bpf_program__attach_map_trace(const struct bpf_program *prog,
+ const struct bpf_map_trace_attach_opts *opts)
+{
+ DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
+ char errmsg[STRERR_BUFSIZE];
+ struct bpf_link *link;
+ int prog_fd, link_fd;
+ __u32 target_fd = 0;
+
+ if (!OPTS_VALID(opts, bpf_map_trace_attach_opts))
+ return ERR_PTR(-EINVAL);
+
+ link_create_opts.map_trace_info = OPTS_GET(opts, link_info, (void *)0);
+ link_create_opts.map_trace_info_len = OPTS_GET(opts, link_info_len, 0);
+
+ prog_fd = bpf_program__fd(prog);
+ if (prog_fd < 0) {
+ pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+ return ERR_PTR(-EINVAL);
+ }
+
+ link = calloc(1, sizeof(*link));
+ if (!link)
+ return ERR_PTR(-ENOMEM);
+ link->detach = &bpf_link__detach_fd;
+
+ link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_MAP,
+ &link_create_opts);
+ if (link_fd < 0) {
+ link_fd = -errno;
+ free(link);
+ pr_warn("prog '%s': failed to attach to map: %s\n",
+ prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
+ return ERR_PTR(link_fd);
+ }
+ link->fd = link_fd;
+ return link;
+}
+
+static struct bpf_link *attach_map_trace(const struct bpf_program *prog,
+ long cookie)
+{
+ struct bpf_map_trace_attach_opts map_trace_opts;
+ struct bpf_map_trace_link_info link_info;
+ enum bpf_map_trace_type trace_type;
+ const char *trace_name = prog->sec_name;
+ const char *map_name = prog->sec_name;
+ char *map_name_cstr;
+ size_t map_name_len;
+ struct bpf_map *map;
+ int slash_seen = 0;
+
+ /*
+ * Map tracing sections are named like this:
+ * map_trace/map_name/trace_type
+ * Assign trace_name and map_name to the beginning of their names.
+ */
+ while (*map_name && *trace_name && slash_seen < 2) {
+ if (slash_seen < 1)
+ map_name++;
+ if (slash_seen < 2)
+ trace_name++;
+ if (*trace_name == '/')
+ slash_seen++;
+ }
+ if (*map_name)
+ ++map_name;
+ if (*trace_name)
+ ++trace_name;
+ if (!*map_name || !*trace_name || slash_seen < 2)
+ return ERR_PTR(-EINVAL);
+
+ if (!strcmp(trace_name, "UPDATE_ELEM"))
+ trace_type = BPF_MAP_TRACE_UPDATE_ELEM;
+ else if (!strcmp(trace_name, "DELETE_ELEM"))
+ trace_type = BPF_MAP_TRACE_DELETE_ELEM;
+ else
+ return ERR_PTR(-EINVAL);
+
+ map_name_len = (trace_name - map_name) - 1;
+ map_name_cstr = malloc(map_name_len + 1);
+ if (!map_name_cstr)
+ return ERR_PTR(-ENOMEM);
+ map_name_cstr[map_name_len] = 0;
+ strncpy(map_name_cstr, map_name, map_name_len);
+ pr_warn("map name cstr: %s\n", map_name_cstr);
+ map = bpf_object__find_map_by_name(prog->obj, map_name_cstr);
+ free(map_name_cstr);
+ if (!map)
+ return ERR_PTR(-EINVAL);
+
+ memset(&link_info, 0, sizeof(link_info));
+ link_info.map_fd = bpf_map__fd(map);
+ link_info.trace_type = trace_type;
+ memset(&map_trace_opts, 0, sizeof(map_trace_opts));
+ map_trace_opts.sz = sizeof(map_trace_opts);
+ map_trace_opts.link_info = &link_info;
+ map_trace_opts.link_info_len = sizeof(link_info);
+ return bpf_program__attach_map_trace(prog, &map_trace_opts);
+}
+
struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
{
if (!prog->sec_def || !prog->sec_def->attach_fn)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index e35490c54eb3..418b65918639 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -358,6 +358,17 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_iter(const struct bpf_program *prog,
const struct bpf_iter_attach_opts *opts);
+struct bpf_map_trace_attach_opts {
+ size_t sz; /* size of this struct for forward/backward compatibility */
+ struct bpf_map_trace_link_info *link_info;
+ __u32 link_info_len;
+};
+#define bpf_map_trace_attach_opts__last_field link_info_len
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_map_trace(const struct bpf_program *prog,
+ const struct bpf_map_trace_attach_opts *opts);
+
struct bpf_insn;
/*
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 9e649cf9e771..84f728b6bd4b 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -384,6 +384,7 @@ LIBBPF_0.5.0 {
btf__load_module_btf;
btf__load_vmlinux_btf;
btf_dump__dump_type_data;
+ bpf_program__attach_map_trace;
libbpf_set_strict_mode;
} LIBBPF_0.4.0;
--
2.33.0.685.g46640cef36-goog
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