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author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2022-05-26 17:48:58 +0300 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2022-05-26 18:36:56 +0300 |
commit | df76e0038370d364d4b2154fa7ddbbccc29f629f (patch) | |
tree | 1fe9ae4cd63529bb266df4dc6ac5d5725befb5f1 /tools/build/feature | |
parent | 982be4775164d4780d9c6a2f38b365f5b5bd16d4 (diff) | |
download | linux-df76e0038370d364d4b2154fa7ddbbccc29f629f.tar.xz |
perf build: Stop using __weak bpf_map_create() to handle older libbpf versions
By adding a feature test for bpf_map_create() and providing a fallback if
it isn't present in older versions of libbpf.
This also fixes the build with torvalds/master at this point:
$ git log --oneline -5 torvalds/master
babf0bb978e3c9fc (torvalds/master) Merge tag 'xfs-5.19-for-linus' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
e375780b631a5fc2 Merge tag 'fsnotify_for_v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
8b728edc5be16179 Merge tag 'fs_for_v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
3f306ea2e18568f6 Merge tag 'dma-mapping-5.19-2022-05-25' of git://git.infradead.org/users/hch/dma-mapping
fbe86daca0ba878b Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
$
Coping with:
$ git log --oneline -2 d16495a982324f75
d16495a982324f75 libbpf: remove bpf_create_map*() APIs
e2371b1632b1c61c libbpf: start 1.0 development cycle
$
As the __weak function fails to build as it calls the now removed
bpf_create_map() API.
Testing:
$ rpm -q libbpf-devel
libbpf-devel-0.4.0-2.fc35.x86_64
$
$ make -C tools/perf BUILD_BPF_SKEL=1 LIBBPF_DYNAMIC=1 O=/tmp/build/perf install-bin
$ cat /tmp/build/perf/feature/test-libbpf-bpf_map_create.make.output
test-libbpf-bpf_map_create.c: In function ‘main’:
test-libbpf-bpf_map_create.c:6:16: error: implicit declaration of function ‘bpf_map_create’; did you mean ‘bpf_map_freeze’? [-Werror=implicit-function-declaration]
6 | return bpf_map_create(0 /* map_type */, NULL /* map_name */, 0, /* key_size */,
| ^~~~~~~~~~~~~~
| bpf_map_freeze
test-libbpf-bpf_map_create.c:6:87: error: expected expression before ‘,’ token
6 | return bpf_map_create(0 /* map_type */, NULL /* map_name */, 0, /* key_size */,
| ^
cc1: all warnings being treated as errors
$
$ objdump -dS /tmp/build/perf/perf | grep '<bpf_map_create>:' -A20
000000000058b290 <bpf_map_create>:
{
58b290: 55 push %rbp
58b291: 48 89 e5 mov %rsp,%rbp
58b294: 48 83 ec 10 sub $0x10,%rsp
58b298: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
58b29f: 00 00
58b2a1: 48 89 45 f8 mov %rax,-0x8(%rbp)
58b2a5: 31 c0 xor %eax,%eax
return bpf_create_map(map_type, key_size, value_size, max_entries, 0);
58b2a7: 48 8b 45 f8 mov -0x8(%rbp),%rax
58b2ab: 64 48 2b 04 25 28 00 sub %fs:0x28,%rax
58b2b2: 00 00
58b2b4: 75 10 jne 58b2c6 <bpf_map_create+0x36>
}
58b2b6: c9 leave
58b2b7: 89 d6 mov %edx,%esi
58b2b9: 89 ca mov %ecx,%edx
58b2bb: 44 89 c1 mov %r8d,%ecx
return bpf_create_map(map_type, key_size, value_size, max_entries, 0);
58b2be: 45 31 c0 xor %r8d,%r8d
$
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/linux-perf-users/Yo+XvQNKL4K5khl2@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/build/feature')
-rw-r--r-- | tools/build/feature/Makefile | 4 | ||||
-rw-r--r-- | tools/build/feature/test-libbpf-bpf_map_create.c | 8 |
2 files changed, 12 insertions, 0 deletions
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile index 5b31a6d063d7..7c2a17e23c30 100644 --- a/tools/build/feature/Makefile +++ b/tools/build/feature/Makefile @@ -59,6 +59,7 @@ FILES= \ test-libbpf.bin \ test-libbpf-btf__load_from_kernel_by_id.bin \ test-libbpf-bpf_prog_load.bin \ + test-libbpf-bpf_map_create.bin \ test-libbpf-bpf_object__next_program.bin \ test-libbpf-bpf_object__next_map.bin \ test-libbpf-btf__raw_data.bin \ @@ -298,6 +299,9 @@ $(OUTPUT)test-libbpf-btf__load_from_kernel_by_id.bin: $(OUTPUT)test-libbpf-bpf_prog_load.bin: $(BUILD) -lbpf +$(OUTPUT)test-libbpf-bpf_map_create.bin: + $(BUILD) -lbpf + $(OUTPUT)test-libbpf-bpf_object__next_program.bin: $(BUILD) -lbpf diff --git a/tools/build/feature/test-libbpf-bpf_map_create.c b/tools/build/feature/test-libbpf-bpf_map_create.c new file mode 100644 index 000000000000..b9f550e332c8 --- /dev/null +++ b/tools/build/feature/test-libbpf-bpf_map_create.c @@ -0,0 +1,8 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <bpf/bpf.h> + +int main(void) +{ + return bpf_map_create(0 /* map_type */, NULL /* map_name */, 0, /* key_size */, + 0 /* value_size */, 0 /* max_entries */, NULL /* opts */); +} |