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2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f 
 kernel/tools/bpf/bpftool/Documentation/bpftool-map.rst
....@@ -15,42 +15,80 @@
1515 	*OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } }
1616 
1717 	*COMMANDS* :=
18
-	{ **show** | **list** | **dump** | **update** | **lookup** | **getnext** | **delete**
19
-	| **pin** | **help** }
18
+	{ **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext**
19
+	| **delete** | **pin** | **help** }
2020 
2121 MAP COMMANDS
2222 =============
2323 
24
-|	**bpftool** **map { show | list }**   [*MAP*]
24
+|	**bpftool** **map** { **show** | **list** }   [*MAP*]
25
+|	**bpftool** **map create**     *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
26
+|		**entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] \
27
+|		[**dev** *NAME*]
2528 |	**bpftool** **map dump**       *MAP*
26
-|	**bpftool** **map update**     *MAP*  **key** *DATA*   **value** *VALUE* [*UPDATE_FLAGS*]
27
-|	**bpftool** **map lookup**     *MAP*  **key** *DATA*
29
+|	**bpftool** **map update**     *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
30
+|	**bpftool** **map lookup**     *MAP* [**key** *DATA*]
2831 |	**bpftool** **map getnext**    *MAP* [**key** *DATA*]
2932 |	**bpftool** **map delete**     *MAP*  **key** *DATA*
3033 |	**bpftool** **map pin**        *MAP*  *FILE*
3134 |	**bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
35
+|	**bpftool** **map peek**       *MAP*
36
+|	**bpftool** **map push**       *MAP* **value** *VALUE*
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+|	**bpftool** **map pop**        *MAP*
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+|	**bpftool** **map enqueue**    *MAP* **value** *VALUE*
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+|	**bpftool** **map dequeue**    *MAP*
40
+|	**bpftool** **map freeze**     *MAP*
3241 |	**bpftool** **map help**
3342 |
34
-|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
43
+|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* }
3544 |	*DATA* := { [**hex**] *BYTES* }
36
-|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
45
+|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
3746 |	*VALUE* := { *DATA* | *MAP* | *PROG* }
3847 |	*UPDATE_FLAGS* := { **any** | **exist** | **noexist** }
48
+|	*TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash**
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+|		| **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash**
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+|		| **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps**
51
+|		| **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash**
52
+|		| **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage**
53
+|		| **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage** }
3954 
4055 DESCRIPTION
4156 ===========
4257 	**bpftool map { show | list }**   [*MAP*]
4358 		  Show information about loaded maps.  If *MAP* is specified
44
-		  show information only about given map, otherwise list all
45
-		  maps currently loaded on the system.
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+		  show information only about given maps, otherwise list all
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+		  maps currently loaded on the system.  In case of **name**,
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+		  *MAP* may match several maps which will all be shown.
4662 
4763 		  Output will start with map ID followed by map type and
4864 		  zero or more named attributes (depending on kernel version).
4965 
50
-	**bpftool map dump**    *MAP*
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-		  Dump all entries in a given *MAP*.
66
+		  Since Linux 5.8 bpftool is able to discover information about
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+		  processes that hold open file descriptors (FDs) against BPF
68
+		  maps. On such kernels bpftool will automatically emit this
69
+		  information as well.
5270 
53
-	**bpftool map update**  *MAP*  **key** *DATA*   **value** *VALUE* [*UPDATE_FLAGS*]
71
+	**bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE*  **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*]
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+		  Create a new map with given parameters and pin it to *bpffs*
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+		  as *FILE*.
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+
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+		  *FLAGS* should be an integer which is the combination of
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+		  desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h
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+		  UAPI header for existing flags).
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+
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+		  To create maps of type array-of-maps or hash-of-maps, the
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+		  **inner_map** keyword must be used to pass an inner map. The
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+		  kernel needs it to collect metadata related to the inner maps
82
+		  that the new map will work with.
83
+
84
+		  Keyword **dev** expects a network interface name, and is used
85
+		  to request hardware offload for the map.
86
+
87
+	**bpftool map dump**    *MAP*
88
+		  Dump all entries in a given *MAP*.  In case of **name**,
89
+		  *MAP* may match several maps which will all be dumped.
90
+
91
+	**bpftool map update**  *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
5492 		  Update map entry for a given *KEY*.
5593 
5694 		  *UPDATE_FLAGS* can be one of: **any** update existing entry
....@@ -58,12 +96,12 @@
5896 		  exists; **noexist** update only if entry doesn't exist.
5997 
6098 		  If the **hex** keyword is provided in front of the bytes
61
-		  sequence, the bytes are parsed as hexadeximal values, even if
99
+		  sequence, the bytes are parsed as hexadecimal values, even if
62100 		  no "0x" prefix is added. If the keyword is not provided, then
63101 		  the bytes are parsed as decimal values, unless a "0x" prefix
64102 		  (for hexadecimal) or a "0" prefix (for octal) is provided.
65103 
66
-	**bpftool map lookup**  *MAP*  **key** *DATA*
104
+	**bpftool map lookup**  *MAP* [**key** *DATA*]
67105 		  Lookup **key** in the map.
68106 
69107 	**bpftool map getnext** *MAP* [**key** *DATA*]
....@@ -75,13 +113,15 @@
75113 	**bpftool map pin**     *MAP*  *FILE*
76114 		  Pin map *MAP* as *FILE*.
77115 
78
-		  Note: *FILE* must be located in *bpffs* mount.
116
+		  Note: *FILE* must be located in *bpffs* mount. It must not
117
+		  contain a dot character ('.'), which is reserved for future
118
+		  extensions of *bpffs*.
79119 
80120 	**bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
81
-		  Read events from a BPF_MAP_TYPE_PERF_EVENT_ARRAY map.
121
+		  Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map.
82122 
83123 		  Install perf rings into a perf event array map and dump
84
-		  output of any bpf_perf_event_output() call in the kernel.
124
+		  output of any **bpf_perf_event_output**\ () call in the kernel.
85125 		  By default read the number of CPUs on the system and
86126 		  install perf ring for each CPU in the corresponding index
87127 		  in the array.
....@@ -93,34 +133,52 @@
93133 		  replace any existing ring.  Any other application will stop
94134 		  receiving events if it installed its rings earlier.
95135 
136
+	**bpftool map peek**  *MAP*
137
+		  Peek next value in the queue or stack.
138
+
139
+	**bpftool map push**  *MAP* **value** *VALUE*
140
+		  Push *VALUE* onto the stack.
141
+
142
+	**bpftool map pop**  *MAP*
143
+		  Pop and print value from the stack.
144
+
145
+	**bpftool map enqueue**  *MAP* **value** *VALUE*
146
+		  Enqueue *VALUE* into the queue.
147
+
148
+	**bpftool map dequeue**  *MAP*
149
+		  Dequeue and print value from the queue.
150
+
151
+	**bpftool map freeze**  *MAP*
152
+		  Freeze the map as read-only from user space. Entries from a
153
+		  frozen map can not longer be updated or deleted with the
154
+		  **bpf**\ () system call. This operation is not reversible,
155
+		  and the map remains immutable from user space until its
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+		  destruction. However, read and write permissions for BPF
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+		  programs to the map remain unchanged.
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+
96159 	**bpftool map help**
97160 		  Print short help message.
98161 
99162 OPTIONS
100163 =======
101
-	-h, --help
102
-		  Print short generic help message (similar to **bpftool help**).
103
-
104
-	-v, --version
105
-		  Print version number (similar to **bpftool version**).
106
-
107
-	-j, --json
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-		  Generate JSON output. For commands that cannot produce JSON, this
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-		  option has no effect.
110
-
111
-	-p, --pretty
112
-		  Generate human-readable JSON output. Implies **-j**.
164
+	.. include:: common_options.rst
113165 
114166 	-f, --bpffs
115167 		  Show file names of pinned maps.
116168 
169
+	-n, --nomount
170
+		  Do not automatically attempt to mount any virtual file system
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+		  (such as tracefs or BPF virtual file system) when necessary.
172
+
117173 EXAMPLES
118174 ========
119175 **# bpftool map show**
176
+
120177 ::
121178 
122179   10: hash  name some_map  flags 0x0
123
-	key 4B  value 8B  max_entries 2048  memlock 167936B
180
+        key 4B  value 8B  max_entries 2048  memlock 167936B
181
+        pids systemd(1)
124182 
125183 The following three commands are equivalent:
126184 
....@@ -137,6 +195,7 @@
137195 
138196 
139197 **# bpftool map dump id 10**
198
+
140199 ::
141200 
142201   key: 00 01 02 03  value: 00 01 02 03 04 05 06 07
....@@ -144,6 +203,7 @@
144203   Found 2 elements
145204 
146205 **# bpftool map getnext id 10 key 0 1 2 3**
206
+
147207 ::
148208 
149209   key:
....@@ -156,6 +216,57 @@
156216 | **# bpftool map pin id 10 /sys/fs/bpf/map**
157217 | **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
158218 
159
-SEE ALSO
160
-========
161
-	**bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-cgroup**\ (8)
219
+Note that map update can also be used in order to change the program references
220
+hold by a program array map. This can be used, for example, to change the
221
+programs used for tail-call jumps at runtime, without having to reload the
222
+entry-point program. Below is an example for this use case: we load a program
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+defining a prog array map, and with a main function that contains a tail call
224
+to other programs that can be used either to "process" packets or to "debug"
225
+processing. Note that the prog array map MUST be pinned into the BPF virtual
226
+file system for the map update to work successfully, as kernel flushes prog
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+array maps when they have no more references from user space (and the update
228
+would be lost as soon as bpftool exits).
229
+
230
+|
231
+| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
232
+| **# bpftool prog --bpffs**
233
+
234
+::
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+
236
+  545: xdp  name main_func  tag 674b4b5597193dc3  gpl
237
+          loaded_at 2018-12-12T15:02:58+0000  uid 0
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+          xlated 240B  jited 257B  memlock 4096B  map_ids 294
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+          pinned /sys/fs/bpf/foo/xdp
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+  546: xdp  name bpf_func_process  tag e369a529024751fc  gpl
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+          loaded_at 2018-12-12T15:02:58+0000  uid 0
242
+          xlated 200B  jited 164B  memlock 4096B
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+          pinned /sys/fs/bpf/foo/process
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+  547: xdp  name bpf_func_debug  tag 0b597868bc7f0976  gpl
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+          loaded_at 2018-12-12T15:02:58+0000  uid 0
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+          xlated 200B  jited 164B  memlock 4096B
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+          pinned /sys/fs/bpf/foo/debug
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+
249
+**# bpftool map**
250
+
251
+::
252
+
253
+  294: prog_array  name jmp_table  flags 0x0
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+          key 4B  value 4B  max_entries 1  memlock 4096B
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+          owner_prog_type xdp  owner jited
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+
257
+|
258
+| **# bpftool map pin id 294 /sys/fs/bpf/bar**
259
+| **# bpftool map dump pinned /sys/fs/bpf/bar**
260
+
261
+::
262
+
263
+  Found 0 elements
264
+
265
+|
266
+| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
267
+| **# bpftool map dump pinned /sys/fs/bpf/bar**
268
+
269
+::
270
+
271
+  key: 00 00 00 00  value: 22 02 00 00
272
+  Found 1 element