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Merge branch 'bpf-bpftool-cleanups'
Quentin Monnet says: ==================== This series contains several minor fixes for bpftool source and documentation. The first patches focus on documentation: addition of an option in the page for "bpftool prog", clean up and update of the same page, and addition of an example of prog array map manipulation in "bpftool map" page. The last two fix warnings susceptible to appear when libbfd is not present (patch 4), or with additional warning flags passed to the compiler (last patch). ==================== Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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‎tools/bpf/bpftool/Documentation/bpftool-map.rst

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@@ -170,6 +170,61 @@ The following three commands are equivalent:
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| **# bpftool map pin id 10 /sys/fs/bpf/map**
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| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
172172
173+
Note that map update can also be used in order to change the program references
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hold by a program array map. This can be used, for example, to change the
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programs used for tail-call jumps at runtime, without having to reload the
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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
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to other programs that can be used either to "process" packets or to "debug"
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processing. Note that the prog array map MUST be pinned into the BPF virtual
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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
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would be lost as soon as bpftool exits).
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|
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| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
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| **# bpftool prog --bpffs**
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::
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545: xdp name main_func tag 674b4b5597193dc3 gpl
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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
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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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**# bpftool map**
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::
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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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|
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| **# bpftool map pin id 294 /sys/fs/bpf/bar**
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| **# bpftool map dump pinned /sys/fs/bpf/bar**
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::
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Found 0 elements
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|
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| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
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| **# bpftool map dump pinned /sys/fs/bpf/bar**
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::
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key: 00 00 00 00 value: 22 02 00 00
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Found 1 element
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173228
SEE ALSO
174229
========
175230
**bpf**\ (2),

‎tools/bpf/bpftool/Documentation/bpftool-prog.rst

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Original file line numberDiff line numberDiff line change
@@ -158,83 +158,94 @@ OPTIONS
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When showing BPF programs, show file names of pinned
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programs.
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-m, --mapcompat
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Allow loading maps with unknown map definitions.
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161164
EXAMPLES
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========
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**# bpftool prog show**
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164168
::
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10: xdp name some_prog tag 005a3d2123620c8b gpl
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loaded_at Sep 29/20:11 uid 0
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xlated 528B jited 370B memlock 4096B map_ids 10
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10: xdp name some_prog tag 005a3d2123620c8b gpl
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loaded_at 2017-09-29T20:11:00+0000 uid 0
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xlated 528B jited 370B memlock 4096B map_ids 10
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**# bpftool --json --pretty prog show**
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172176
::
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174-
{
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"programs": [{
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"id": 10,
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"type": "xdp",
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"tag": "005a3d2123620c8b",
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"gpl_compatible": true,
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"loaded_at": "Sep 29/20:11",
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"uid": 0,
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"bytes_xlated": 528,
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"jited": true,
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"bytes_jited": 370,
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"bytes_memlock": 4096,
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"map_ids": [10
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]
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}
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]
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}
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[{
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"id": 10,
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"type": "xdp",
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"tag": "005a3d2123620c8b",
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"gpl_compatible": true,
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"loaded_at": 1506715860,
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"uid": 0,
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"bytes_xlated": 528,
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"jited": true,
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"bytes_jited": 370,
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"bytes_memlock": 4096,
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"map_ids": [10
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]
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}
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]
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|
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| **# bpftool prog dump xlated id 10 file /tmp/t**
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| **# ls -l /tmp/t**
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| -rw------- 1 root root 560 Jul 22 01:42 /tmp/t
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**# bpftool prog dum jited tag 005a3d2123620c8b**
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::
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-rw------- 1 root root 560 Jul 22 01:42 /tmp/t
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**# bpftool prog dump jited tag 005a3d2123620c8b**
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::
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push %rbp
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mov %rsp,%rbp
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sub $0x228,%rsp
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sub $0x28,%rbp
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mov %rbx,0x0(%rbp)
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0: push %rbp
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1: mov %rsp,%rbp
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2: sub $0x228,%rsp
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3: sub $0x28,%rbp
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4: mov %rbx,0x0(%rbp)
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|
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| **# mount -t bpf none /sys/fs/bpf/**
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| **# bpftool prog pin id 10 /sys/fs/bpf/prog**
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| **# bpftool prog load ./my_prog.o /sys/fs/bpf/prog2**
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| **# ls -l /sys/fs/bpf/**
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| -rw------- 1 root root 0 Jul 22 01:43 prog
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| -rw------- 1 root root 0 Jul 22 01:44 prog2
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**# bpftool prog dum jited pinned /sys/fs/bpf/prog opcodes**
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::
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-rw------- 1 root root 0 Jul 22 01:43 prog
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-rw------- 1 root root 0 Jul 22 01:44 prog2
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**# bpftool prog dump jited pinned /sys/fs/bpf/prog opcodes**
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217225
::
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219-
push %rbp
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55
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mov %rsp,%rbp
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48 89 e5
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sub $0x228,%rsp
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48 81 ec 28 02 00 00
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sub $0x28,%rbp
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mov %rbx,0x0(%rbp)
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48 89 5d 00
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0: push %rbp
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55
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1: mov %rsp,%rbp
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48 89 e5
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4: sub $0x228,%rsp
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48 81 ec 28 02 00 00
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b: sub $0x28,%rbp
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48 83 ed 28
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f: mov %rbx,0x0(%rbp)
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48 89 5d 00
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|
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| **# bpftool prog load xdp1_kern.o /sys/fs/bpf/xdp1 type xdp map name rxcnt id 7**
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| **# bpftool prog show pinned /sys/fs/bpf/xdp1**
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| 9: xdp name xdp_prog1 tag 539ec6ce11b52f98 gpl
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| loaded_at 2018-06-25T16:17:31-0700 uid 0
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| xlated 488B jited 336B memlock 4096B map_ids 7
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| **# rm /sys/fs/bpf/xdp1**
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|
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::
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9: xdp name xdp_prog1 tag 539ec6ce11b52f98 gpl
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loaded_at 2018-06-25T16:17:31-0700 uid 0
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xlated 488B jited 336B memlock 4096B map_ids 7
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**# rm /sys/fs/bpf/xdp1**
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SEE ALSO
240251
========

‎tools/bpf/bpftool/common.c

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@@ -28,7 +28,7 @@
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#define BPF_FS_MAGIC 0xcafe4a11
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#endif
3030

31-
void p_err(const char *fmt, ...)
31+
void __printf(1, 2) p_err(const char *fmt, ...)
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{
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va_list ap;
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@@ -46,7 +46,7 @@ void p_err(const char *fmt, ...)
4646
va_end(ap);
4747
}
4848

49-
void p_info(const char *fmt, ...)
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void __printf(1, 2) p_info(const char *fmt, ...)
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{
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va_list ap;
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‎tools/bpf/bpftool/json_writer.c

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@@ -20,6 +20,7 @@
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#include <malloc.h>
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#include <inttypes.h>
2222
#include <stdint.h>
23+
#include <linux/compiler.h>
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2425
#include "json_writer.h"
2526

@@ -157,15 +158,16 @@ void jsonw_name(json_writer_t *self, const char *name)
157158
putc(' ', self->out);
158159
}
159160

160-
void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
161+
void __printf(2, 0)
162+
jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
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{
162164
jsonw_eor(self);
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putc('"', self->out);
164166
vfprintf(self->out, fmt, ap);
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putc('"', self->out);
166168
}
167169

168-
void jsonw_printf(json_writer_t *self, const char *fmt, ...)
170+
void __printf(2, 3) jsonw_printf(json_writer_t *self, const char *fmt, ...)
169171
{
170172
va_list ap;
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‎tools/bpf/bpftool/main.h

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@@ -147,8 +147,8 @@ int prog_parse_fd(int *argc, char ***argv);
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int map_parse_fd(int *argc, char ***argv);
148148
int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
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150-
#ifdef HAVE_LIBBFD_SUPPORT
151150
struct bpf_prog_linfo;
151+
#ifdef HAVE_LIBBFD_SUPPORT
152152
void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
153153
const char *arch, const char *disassembler_options,
154154
const struct btf *btf,

‎tools/bpf/bpftool/prog.c

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Original file line numberDiff line numberDiff line change
@@ -32,7 +32,7 @@ static const char * const attach_type_strings[] = {
3232
[__MAX_BPF_ATTACH_TYPE] = NULL,
3333
};
3434

35-
enum bpf_attach_type parse_attach_type(const char *str)
35+
static enum bpf_attach_type parse_attach_type(const char *str)
3636
{
3737
enum bpf_attach_type type;
3838

@@ -798,7 +798,7 @@ struct map_replace {
798798
char *name;
799799
};
800800

801-
int map_replace_compar(const void *p1, const void *p2)
801+
static int map_replace_compar(const void *p1, const void *p2)
802802
{
803803
const struct map_replace *a = p1, *b = p2;
804804

‎tools/bpf/bpftool/xlated_dumper.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -81,7 +81,7 @@ struct kernel_sym *kernel_syms_search(struct dump_data *dd,
8181
sizeof(*dd->sym_mapping), kernel_syms_cmp) : NULL;
8282
}
8383

84-
static void print_insn(void *private_data, const char *fmt, ...)
84+
static void __printf(2, 3) print_insn(void *private_data, const char *fmt, ...)
8585
{
8686
va_list args;
8787

@@ -90,7 +90,7 @@ static void print_insn(void *private_data, const char *fmt, ...)
9090
va_end(args);
9191
}
9292

93-
static void
93+
static void __printf(2, 3)
9494
print_insn_for_graph(void *private_data, const char *fmt, ...)
9595
{
9696
char buf[64], *p;
@@ -121,7 +121,8 @@ print_insn_for_graph(void *private_data, const char *fmt, ...)
121121
printf("%s", buf);
122122
}
123123

124-
static void print_insn_json(void *private_data, const char *fmt, ...)
124+
static void __printf(2, 3)
125+
print_insn_json(void *private_data, const char *fmt, ...)
125126
{
126127
unsigned int l = strlen(fmt);
127128
char chomped_fmt[l];

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