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4 Commits

Author SHA1 Message Date
Florent Revest
d6a6a55518 libbpf: Move BPF_SEQ_PRINTF and BPF_SNPRINTF to bpf_helpers.h 
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
 2021-05-26 10:45:41 -07:00
Dave Marchevsky
c77cec5c20 bpf/selftests: Add bpf_get_task_stack retval bounds test_prog 
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
 2021-04-19 18:23:33 -07:00
Song Liu
9ff79af333 selftests/bpf: Fix compilation error of bpf_iter_task_stack.c 
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: c7568114bc56 ("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
 2020-07-03 23:25:40 +02:00
Song Liu
c7568114bc selftests/bpf: Add bpf_iter test with bpf_get_task_stack() 
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
 2020-07-01 08:23:59 -07:00