Re: [PATCH bpf-next 2/3] bpf: allow %pB in bpf_seq_printf()

[Song Liu]

> On Jun 23, 2020, at 8:29 AM, Daniel Borkmann <dan...@iogearbox.net> wrote:
> 
> On 6/23/20 9:08 AM, Song Liu wrote:
>> This makes it easy to dump stack trace with bpf_seq_printf().
>> Signed-off-by: Song Liu <songliubrav...@fb.com>
>> ---
>>  kernel/trace/bpf_trace.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
>> index 2c13bcb5c2bce..ced3176801ae8 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -636,7 +636,8 @@ BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, 
>> fmt, u32, fmt_size,
>>              if (fmt[i] == 'p') {
>>                      if (fmt[i + 1] == 0 ||
>>                          fmt[i + 1] == 'K' ||
>> -                        fmt[i + 1] == 'x') {
>> +                        fmt[i + 1] == 'x' ||
>> +                        fmt[i + 1] == 'B') {
>>                              /* just kernel pointers */
>>                              params[fmt_cnt] = args[fmt_cnt];
>>                              fmt_cnt++;
> 
> Why only bpf_seq_printf(), what about bpf_trace_printk()?

The use case we are looking at needs bpf_seq_printf(). Let me also add it to
bpf_trace_printk(). 

Thanks,
Song