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From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: "Alexander Lobakin" <alexandr.lobakin@intel.com>,
	"Larysa Zaremba" <larysa.zaremba@intel.com>,
	"Michal Swiatkowski" <michal.swiatkowski@linux.intel.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Björn Töpel" <bjorn@kernel.org>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Maciej Fijalkowski" <maciej.fijalkowski@intel.com>,
	"Jonathan Lemon" <jonathan.lemon@gmail.com>,
	"Toke Hoiland-Jorgensen" <toke@redhat.com>,
	"Lorenzo Bianconi" <lorenzo@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Yajun Deng" <yajun.deng@linux.dev>,
	"Willem de Bruijn" <willemb@google.com>,
	bpf@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, xdp-hints@xdp-project.net
Subject: [xdp-hints] [PATCH RFC bpf-next 26/52] bpf, btf: add a pair of function to work with the BTF ID + type ID pair
Date: Tue, 28 Jun 2022 21:47:46 +0200	[thread overview]
Message-ID: <20220628194812.1453059-27-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <20220628194812.1453059-1-alexandr.lobakin@intel.com>

Add a kernel counterpart of libbpf_get_type_btf_id() to easily get
the pair of BTF ID << 32 | type ID for the provided type. Drivers
and the XDP core will use it to handle different XDP generic
metadata formats.

Also add a function to return matching type string (e.g.
"struct foo") index from an array of such strings for a given BTF
ID + type ID pair. The intention is to be able to quickly identify
the ID received from somewhere else and to assign some own constant
identifiers to the supported types.
To not do:

	priv->foo_id = bpf_get_type_btf_id("struct foo");
	priv->bar_id = bpf_get_type_btf_id("struct bar");

[...]

	if (id == priv->foo_id)
		do_smth_for_foo();
	else if (id == priv->bar_id)
		do_smth_for_bar();
	else
		unsupp();

but instead:

const char * const supp[] = {
	[FOO_ID] = "struct foo",
	[BAR_ID] = "struct bar",
	NULL,				// serves as a terminator, can be ""
};

[...]

	type = bpf_match_type_btf_id(supp, id);
	switch(type) {
	case FOO_ID:
		do_smth_for_foo();
		break;
	case BAR_ID:
		do_smth_for_bar();
		break;
	default:
		unsupp();
		break;
	}

Aux function:
 * btf_kind_from_str(): returns the kind of the provided full type
   string and removes the kind identifier to e.g. be able to pass it
   directly to btf_find_by_name_kind(). For example, "struct foo"
   becomes "foo" and the return value will be BTF_KIND_STRUCT.
 * btf_get_by_id() is a shorthand to quickly get the BTF by its ID,
   factored-out from btf_get_fd_by_id().

Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
---
 include/linux/btf.h |  13 +++++
 kernel/bpf/btf.c    | 133 ++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 140 insertions(+), 6 deletions(-)

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 1bfed7fa0428..36bc9c499409 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -386,6 +386,8 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
 int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
 				struct module *owner);
+int bpf_get_type_btf_id(const char *type, u64 *res_id);
+int bpf_match_type_btf_id(const char * const *list, u64 id);
 #else
 static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
 						    u32 type_id)
@@ -418,6 +420,17 @@ static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dt
 {
 	return 0;
 }
+static inline int bpf_get_type_btf_id(const char *type, u64 *res_id)
+{
+	if (res_id)
+		*res_id = 0;
+
+	return -ENOSYS;
+}
+static inline int bpf_match_type_btf_id(const char * const *list, u64 id)
+{
+	return -ENOSYS;
+}
 #endif
 
 #endif
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 2e2066d6af94..dc316c43a348 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -317,6 +317,28 @@ const char *btf_type_str(const struct btf_type *t)
 	return btf_kind_str[BTF_INFO_KIND(t->info)];
 }
 
+static u32 btf_kind_from_str(const char **type)
+{
+	const char *pos, *orig = *type;
+	u32 kind;
+	int len;
+
+	pos = strchr(orig, ' ');
+	if (pos) {
+		len = pos - orig;
+		*type = pos + 1;
+	} else {
+		len = strlen(orig);
+	}
+
+	for (kind = BTF_KIND_UNKN; kind < NR_BTF_KINDS; kind++) {
+		if (!strncasecmp(orig, btf_kind_str[kind], len))
+			break;
+	}
+
+	return kind < NR_BTF_KINDS ? kind : BTF_KIND_UNKN;
+}
+
 /* Chunk size we use in safe copy of data to be shown. */
 #define BTF_SHOW_OBJ_SAFE_SIZE		32
 
@@ -579,6 +601,110 @@ static s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
 	return ret;
 }
 
+/**
+ * bpf_get_type_btf_id - get the pair BTF ID + type ID for a given type
+ * @type: pointer to the name of the type to look for
+ * @res_id: pointer to write the result to
+ *
+ * Tries to find the BTF corresponding to the provided type (full string) and
+ * write the pair of BTF ID << 32 | type ID. Such coded __u64 are being used
+ * in XDP generic-compatible metadata to distinguish between different
+ * metadata structures.
+ * @res_id can be %NULL to only check if a particular type exists within
+ * the BTF.
+ *
+ * Returns 0 in case of success, an error code otherwise.
+ */
+int bpf_get_type_btf_id(const char *type, u64 *res_id)
+{
+	struct btf *btf = NULL;
+	s32 type_id;
+	u32 kind;
+
+	if (res_id)
+		*res_id = 0;
+
+	if (!type || !*type)
+		return -EINVAL;
+
+	kind = btf_kind_from_str(&type);
+
+	type_id = bpf_find_btf_id(type, kind, &btf);
+	if (type_id > 0 && res_id)
+		*res_id = ((u64)btf_obj_id(btf) << 32) | type_id;
+
+	btf_put(btf);
+
+	return min(type_id, 0);
+}
+EXPORT_SYMBOL_GPL(bpf_get_type_btf_id);
+
+static struct btf *btf_get_by_id(u32 id)
+{
+	struct btf *btf;
+
+	rcu_read_lock();
+	btf = idr_find(&btf_idr, id);
+	if (!btf || !refcount_inc_not_zero(&btf->refcnt))
+		btf = ERR_PTR(-ENOENT);
+	rcu_read_unlock();
+
+	return btf;
+}
+
+/**
+ * bpf_match_type_btf_id - find a type name corresponding to a given full ID
+ * @list: pointer to the %NULL-terminated list of type names
+ * @id: full ID (BTF ID + type ID) of the type to look
+ *
+ * Do the opposite to what bpf_get_type_btf_id() does: looks over the
+ * candidates in %NULL-terminated @list and tries to find a match for
+ * the given ID. If found, returns its index.
+ *
+ * Returns a string array element index on success, an error code otherwise.
+ */
+int bpf_match_type_btf_id(const char * const *list, u64 id)
+{
+	const struct btf_type *t;
+	int ret = -ENOENT;
+	const char *name;
+	struct btf *btf;
+	u32 kind;
+
+	btf = btf_get_by_id(upper_32_bits(id));
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+
+	t = btf_type_by_id(btf, lower_32_bits(id));
+	if (!t)
+		goto err_put;
+
+	name = btf_name_by_offset(btf, t->name_off);
+	if (!name) {
+		ret = -EINVAL;
+		goto err_put;
+	}
+
+	kind = BTF_INFO_KIND(t->info);
+
+	for (u32 i = 0; ; i++) {
+		const char *cand = list[i];
+
+		if (!cand)
+			break;
+
+		if (btf_kind_from_str(&cand) == kind && !strcmp(cand, name)) {
+			ret = i;
+			break;
+		}
+	}
+
+err_put:
+	btf_put(btf);
+
+	return ret;
+}
+
 const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
 					       u32 id, u32 *res_id)
 {
@@ -6804,12 +6930,7 @@ int btf_get_fd_by_id(u32 id)
 	struct btf *btf;
 	int fd;
 
-	rcu_read_lock();
-	btf = idr_find(&btf_idr, id);
-	if (!btf || !refcount_inc_not_zero(&btf->refcnt))
-		btf = ERR_PTR(-ENOENT);
-	rcu_read_unlock();
-
+	btf = btf_get_by_id(id);
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
-- 
2.36.1


  parent reply	other threads:[~2022-06-28 19:49 UTC|newest]

Thread overview: 98+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-28 19:47 [xdp-hints] [PATCH RFC bpf-next 00/52] bpf, xdp: introduce and use Generic Hints/metadata Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 01/52] libbpf: factor out BTF loading from load_module_btfs() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 02/52] libbpf: try to load vmlinux BTF from the kernel first Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 03/52] libbpf: add function to get the pair BTF ID + type ID for a given type Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 04/52] libbpf: patch module BTF ID into BPF insns Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 05/52] net, xdp: decouple XDP code from the core networking code Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 06/52] bpf: pass a pointer to union bpf_attr to bpf_link_ops::update_prog() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 07/52] net, xdp: remove redundant arguments from dev_xdp_{at,de}tach_link() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 08/52] net, xdp: factor out XDP install arguments to a separate structure Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 09/52] net, xdp: add ability to specify BTF ID for XDP metadata Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 10/52] net, xdp: add ability to specify frame size threshold " Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 11/52] libbpf: factor out __bpf_set_link_xdp_fd_replace() args into a struct Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 12/52] libbpf: add ability to set the BTF/type ID on setting XDP prog Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 13/52] libbpf: add ability to set the meta threshold " Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 14/52] libbpf: pass &bpf_link_create_opts directly to bpf_program__attach_fd() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 15/52] libbpf: add bpf_program__attach_xdp_opts() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 16/52] selftests/bpf: expand xdp_link to check that setting meta opts works Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 17/52] samples/bpf: pass a struct to sample_install_xdp() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 18/52] samples/bpf: add ability to specify metadata threshold Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 19/52] stddef: make __struct_group() UAPI C++-friendly Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 20/52] net, xdp: move XDP metadata helpers into new xdp_meta.h Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 21/52] net, xdp: allow metadata > 32 Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 22/52] net, skbuff: add ability to skip skb metadata comparison Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 23/52] net, skbuff: constify the @skb argument of skb_hwtstamps() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 24/52] bpf, xdp: declare generic XDP metadata structure Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 25/52] net, xdp: add basic generic metadata accessors Alexander Lobakin
2022-06-28 19:47 ` Alexander Lobakin [this message]
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 27/52] net, xdp: add &sk_buff <-> &xdp_meta_generic converters Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 28/52] net, xdp: prefetch data a bit when building an skb from an &xdp_frame Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 29/52] net, xdp: try to fill skb fields when converting " Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 30/52] net, gro: decouple GRO from the NAPI layer Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 31/52] net, gro: expose some GRO API to use outside of NAPI Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 32/52] bpf, cpumap: switch to GRO from netif_receive_skb_list() Alexander Lobakin
2024-08-07 20:38   ` [xdp-hints] " Daniel Xu
2024-08-08  4:54     ` Lorenzo Bianconi
2024-08-08 11:57       ` Alexander Lobakin
2024-08-08 17:22         ` Lorenzo Bianconi
2024-08-08 20:52         ` Daniel Xu
2024-08-09 10:02           ` Jesper Dangaard Brouer
2024-08-09 12:20           ` Alexander Lobakin
2024-08-09 12:45             ` Toke Høiland-Jørgensen
2024-08-09 12:56               ` Alexander Lobakin
2024-08-09 13:42                 ` Toke Høiland-Jørgensen
2024-08-10  0:54                   ` Martin KaFai Lau
2024-08-10  8:02                   ` Lorenzo Bianconi
2024-08-13  1:33             ` Jakub Kicinski
2024-08-13  9:51               ` Jesper Dangaard Brouer
2024-08-10  8:00         ` Lorenzo Bianconi
2024-08-13 14:09         ` Alexander Lobakin
2024-08-13 14:54           ` Toke Høiland-Jørgensen
2024-08-13 15:57             ` Jesper Dangaard Brouer
2024-08-19 14:50               ` Alexander Lobakin
2024-08-21  0:29                 ` Daniel Xu
2024-08-21 13:16                   ` Alexander Lobakin
2024-08-21 16:36                     ` Daniel Xu
2024-08-13 16:14           ` Lorenzo Bianconi
2024-08-13 16:27           ` Lorenzo Bianconi
2024-08-13 16:31             ` Alexander Lobakin
2024-08-08 20:44       ` Daniel Xu
2024-08-09  9:32         ` Jesper Dangaard Brouer
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 33/52] bpf, cpumap: add option to set a timeout for deferred flush Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 34/52] samples/bpf: add 'timeout' option to xdp_redirect_cpu Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 35/52] net, skbuff: introduce napi_skb_cache_get_bulk() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 36/52] bpf, cpumap: switch to napi_skb_cache_get_bulk() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 37/52] rcupdate: fix access helpers for incomplete struct pointers on GCC < 10 Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 38/52] net, xdp: remove unused xdp_attachment_info::flags Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 39/52] net, xdp: make &xdp_attachment_info a bit more useful in drivers Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 40/52] net, xdp: add an RCU version of xdp_attachment_setup() Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 41/52] net, xdp: replace net_device::xdp_prog pointer with &xdp_attachment_info Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 42/52] net, xdp: shortcut skb->dev in bpf_prog_run_generic_xdp() Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 43/52] net, xdp: build XDP generic metadata on Generic (skb) XDP path Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 44/52] net, ice: allow XDP prog hot-swapping Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 45/52] net, ice: consolidate all skb fields processing Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 46/52] net, ice: use an onstack &xdp_meta_generic_rx to store HW frame info Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 47/52] net, ice: build XDP generic metadata Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 48/52] libbpf: compress Endianness ops with a macro Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 49/52] libbpf: add LE <--> CPU conversion helpers Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 50/52] libbpf: introduce a couple memory access helpers Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 51/52] selftests/bpf: fix using test_xdp_meta BPF prog via skeleton infra Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 52/52] selftests/bpf: add XDP Generic Hints selftest Alexander Lobakin
2022-06-29  6:15 ` [xdp-hints] Re: [PATCH RFC bpf-next 00/52] bpf, xdp: introduce and use Generic Hints/metadata John Fastabend
2022-06-29 13:43   ` Toke Høiland-Jørgensen
2022-07-04 15:44     ` Alexander Lobakin
2022-07-04 17:13       ` Jesper Dangaard Brouer
2022-07-05 14:38         ` Alexander Lobakin
2022-07-05 19:08           ` Daniel Borkmann
2022-07-04 17:14       ` Toke Høiland-Jørgensen
2022-07-05 15:41         ` Alexander Lobakin
2022-07-05 18:51           ` Toke Høiland-Jørgensen
2022-07-06 13:50             ` Alexander Lobakin
2022-07-06 23:22               ` Toke Høiland-Jørgensen
2022-07-07 11:41                 ` Jesper Dangaard Brouer
2022-07-12 10:33                 ` Magnus Karlsson
2022-07-12 14:14                   ` Jesper Dangaard Brouer
2022-07-15 11:11                     ` Magnus Karlsson
2022-06-29 17:56   ` Zvi Effron
2022-06-30  7:39     ` Magnus Karlsson
2022-07-04 15:31   ` Alexander Lobakin

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