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From: Yonghong Song <yhs@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 6/8] bpftool: print local function pointer properly
Date: Mon, 8 Feb 2021 22:42:19 -0800	[thread overview]
Message-ID: <f88e66a3-6456-180b-b5f2-1655fbb998ae@fb.com> (raw)
In-Reply-To: <CAEf4BzYC27CGJKuWWRmbKGUBoGhkFiftT+omyD9bkbT3wub1vQ@mail.gmail.com>



On 2/8/21 10:22 AM, Andrii Nakryiko wrote:
> On Thu, Feb 4, 2021 at 5:53 PM Yonghong Song <yhs@fb.com> wrote:
>>
>> With later hashmap example, using bpftool xlated output may
>> look like:
>>    int dump_task(struct bpf_iter__task * ctx):
>>    ; struct task_struct *task = ctx->task;
>>       0: (79) r2 = *(u64 *)(r1 +8)
>>    ; if (task == (void *)0 || called > 0)
>>    ...
>>      19: (18) r2 = subprog[+18]
>>      30: (18) r2 = subprog[+26]
>>    ...
>>    36: (95) exit
>>    __u64 check_hash_elem(struct bpf_map * map, __u32 * key, __u64 * val,
>>                          struct callback_ctx * data):
>>    ; struct bpf_iter__task *ctx = data->ctx;
>>      37: (79) r5 = *(u64 *)(r4 +0)
>>    ...
>>      55: (95) exit
>>    __u64 check_percpu_elem(struct bpf_map * map, __u32 * key,
>>                            __u64 * val, void * unused):
>>    ; check_percpu_elem(struct bpf_map *map, __u32 *key, __u64 *val, void *unused)
>>      56: (bf) r6 = r3
>>    ...
>>      83: (18) r2 = subprog[+-46]
> 
> this +-46 looks very confusing...

Make sense, will use %+d to have either +46 or -46.

> 
>>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>> ---
>>   tools/bpf/bpftool/xlated_dumper.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
>> index 8608cd68cdd0..7bdd90503727 100644
>> --- a/tools/bpf/bpftool/xlated_dumper.c
>> +++ b/tools/bpf/bpftool/xlated_dumper.c
>> @@ -196,6 +196,9 @@ static const char *print_imm(void *private_data,
>>          else if (insn->src_reg == BPF_PSEUDO_MAP_VALUE)
>>                  snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
>>                           "map[id:%u][0]+%u", insn->imm, (insn + 1)->imm);
>> +       else if (insn->src_reg == BPF_PSEUDO_FUNC)
>> +               snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
>> +                        "subprog[+%d]", insn->imm + 1);
> 
> why not `subprog[%+d]` instead (see above about confusing output)
> 
>>          else
>>                  snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
>>                           "0x%llx", (unsigned long long)full_imm);
>> --
>> 2.24.1
>>

  reply	other threads:[~2021-02-09  6:43 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-04 23:48 [PATCH bpf-next 0/8] bpf: add bpf_for_each_map_elem() helper Yonghong Song
2021-02-04 23:48 ` [PATCH bpf-next 1/8] bpf: refactor BPF_PSEUDO_CALL checking as a helper function Yonghong Song
2021-02-05  5:59   ` Alexei Starovoitov
2021-02-04 23:48 ` [PATCH bpf-next 2/8] bpf: add bpf_for_each_map_elem() helper Yonghong Song
2021-02-05  5:49   ` Alexei Starovoitov
2021-02-05 17:39     ` Yonghong Song
2021-02-08 18:16   ` Andrii Nakryiko
2021-02-09  6:41     ` Yonghong Song
2021-02-09 17:33       ` Andrii Nakryiko
2021-02-04 23:48 ` [PATCH bpf-next 3/8] bpf: add hashtab support for " Yonghong Song
2021-02-05  6:23   ` Alexei Starovoitov
2021-02-05 17:49     ` Yonghong Song
2021-02-04 23:48 ` [PATCH bpf-next 4/8] bpf: add arraymap " Yonghong Song
2021-02-04 23:48 ` [PATCH bpf-next 5/8] libbpf: support local function pointer relocation Yonghong Song
2021-02-08 18:52   ` Andrii Nakryiko
2021-02-09  6:56     ` Yonghong Song
2021-02-09 17:31       ` Andrii Nakryiko
2021-02-04 23:48 ` [PATCH bpf-next 6/8] bpftool: print local function pointer properly Yonghong Song
2021-02-08 18:22   ` Andrii Nakryiko
2021-02-09  6:42     ` Yonghong Song [this message]
2021-02-04 23:48 ` [PATCH bpf-next 7/8] selftests/bpf: add hashmap test for bpf_for_each_map_elem() helper Yonghong Song
2021-02-08 18:34   ` Andrii Nakryiko
2021-02-09  6:46     ` Yonghong Song
2021-02-09 17:36       ` Andrii Nakryiko
2021-02-04 23:48 ` [PATCH bpf-next 8/8] selftests/bpf: add arraymap " Yonghong Song
2021-02-08 18:35   ` Andrii Nakryiko
2021-02-09  6:50     ` Yonghong Song
2021-02-09 17:38       ` Andrii Nakryiko

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