These macros are convenient wrappers around the bpf_seq_printf and
bpf_snprintf helpers. They are currently provided by bpf_tracing.h which
targets low level tracing primitives. bpf_helpers.h is a better fit.
The __bpf_narg and __bpf_apply are needed in both files and provided
twice. __bpf_empty isn't used anywhere and is removed from bpf_tracing.h
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210526164643.2881368-1-revest@chromium.org
Add a libbpf test prog which feeds bpf_get_task_stack's return value
into seq_write after confirming it's positive. No attempt to bound the
value from above is made.
Load will fail if verifier does not refine retval range based on buf sz
input to bpf_get_task_stack.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210416204704.2816874-4-davemarchevsky@fb.com
BPF selftests show a compilation error as follows:
libbpf: invalid relo for 'entries' in special section 0xfff2; forgot to
initialize global var?..
Fix it by initializing 'entries' to zeros.
Fixes: c7568114bc ("selftests/bpf: Add bpf_iter test with bpf_get_task_stack()")
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200703181719.3747072-1-songliubraving@fb.com
The new test is similar to other bpf_iter tests. It dumps all
/proc/<pid>/stack to a seq_file. Here is some example output:
pid: 2873 num_entries: 3
[<0>] worker_thread+0xc6/0x380
[<0>] kthread+0x135/0x150
[<0>] ret_from_fork+0x22/0x30
pid: 2874 num_entries: 9
[<0>] __bpf_get_stack+0x15e/0x250
[<0>] bpf_prog_22a400774977bb30_dump_task_stack+0x4a/0xb3c
[<0>] bpf_iter_run_prog+0x81/0x170
[<0>] __task_seq_show+0x58/0x80
[<0>] bpf_seq_read+0x1c3/0x3b0
[<0>] vfs_read+0x9e/0x170
[<0>] ksys_read+0xa7/0xe0
[<0>] do_syscall_64+0x4c/0xa0
[<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Note: bpf_iter test as-is doesn't print the contents of the seq_file. To
see the example above, it is necessary to add printf() to do_dummy_read.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630062846.664389-5-songliubraving@fb.com
