[PATCH 1/2] trace: add support for "trace clear"

[Jerome Forissier]

On 12/13/24 13:16, Ilias Apalodimas wrote:
> Thanks,
> 
> Apologies I missed something else as well
> 
> On Fri, 13 Dec 2024 at 14:14, Jerome Forissier
> <jerome.forissier at linaro.org> wrote:
>>
>>
>>
>> On 12/13/24 13:09, Ilias Apalodimas wrote:
>>> Hi Jerome
>>>
>>> On Mon, 9 Dec 2024 at 17:32, Jerome Forissier
>>> <jerome.forissier at linaro.org> wrote:
>>>>
>>>> Implement a "trace clear" command to delete the currently accumulated
>>>> trace data. This comes handy when someone needs to trace a particular
>>>> command. For example:
>>>>
>>>>   => trace clear; dhcp; trace pause
>>>>   => trace stats
>>>>   => trace calls 0x02100000 0x10000000
>>>>   => tftpput $profbase $profoffset 192.168.0.16:trace.bin
>>>>
>>>> Signed-off-by: Jerome Forissier <jerome.forissier at linaro.org>
>>>> ---
>>>>  cmd/trace.c     | 13 ++++++++++++-
>>>>  include/trace.h |  2 ++
>>>>  lib/trace.c     | 47 +++++++++++++++++++++++++++++++++--------------
>>>>  3 files changed, 47 insertions(+), 15 deletions(-)
>>>>
>>>> diff --git a/cmd/trace.c b/cmd/trace.c
>>>> index 937e6a682ad..e95ac7ca9da 100644
>>>> --- a/cmd/trace.c
>>>> +++ b/cmd/trace.c
>>>> @@ -87,8 +87,18 @@ int do_trace(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
>>>>                 trace_set_enabled(0);
>>>>                 break;
>>>>         case 'c':
>>>> -               if (create_call_list(argc, argv))
>>>> +               switch (*(cmd + 1)) {
>>>> +               case 'a':
>>>> +                       if (create_call_list(argc, argv))
>>>> +                               return cmd_usage(cmdtp);
>>>> +                       break;
>>>> +               case 'l':
>>>> +                       if (trace_clear())
>>>> +                               return CMD_RET_FAILURE;
>>>> +                       break;
>>>
>>> Instead of this, mind changing the command to trace wipe or something similar?
>>> Then we can have a discrete case for 'w' rather than scanning for a string
>>
>> Good idea.
>>
>> Thanks,
>> --
>> Jerome
>>
>>>
>>> Cheers
>>> /Ilias
>>>> +               default:
>>>>                         return cmd_usage(cmdtp);
>>>> +               }
>>>>                 break;
>>>>         case 'r':
>>>>                 trace_set_enabled(1);
>>>> @@ -113,6 +123,7 @@ U_BOOT_CMD(
>>>>         "stats                        - display tracing statistics\n"
>>>>         "trace pause                        - pause tracing\n"
>>>>         "trace resume                       - resume tracing\n"
>>>> +       "trace clear                        - clear traces\n"
>>>>         "trace funclist [<addr> <size>]     - dump function list into buffer\n"
>>>>         "trace calls  [<addr> <size>]       "
>>>>                 "- dump function call trace into buffer"
>>>> diff --git a/include/trace.h b/include/trace.h
>>>> index 763d6d1255a..782eaae2fc2 100644
>>>> --- a/include/trace.h
>>>> +++ b/include/trace.h
>>>> @@ -100,6 +100,8 @@ void trace_set_enabled(int enabled);
>>>>
>>>>  int trace_early_init(void);
>>>>
>>>> +int trace_clear(void);
>>>> +
>>>>  /**
>>>>   * Init the trace system
>>>>   *
>>>> diff --git a/lib/trace.c b/lib/trace.c
>>>> index cabbe47b58a..def9f912c92 100644
>>>> --- a/lib/trace.c
>>>> +++ b/lib/trace.c
>>>> @@ -351,14 +351,8 @@ static int get_func_count(void)
>>>>         return gd->mon_len / FUNC_SITE_SIZE;
>>>>  }
>>>>
>>>> -/**
>>>> - * trace_init() - initialize the tracing system and enable it
>>>> - *
>>>> - * @buff:      Pointer to trace buffer
>>>> - * @buff_size: Size of trace buffer
>>>> - * Return:     0 if ok
>>>> - */
>>>> -int notrace trace_init(void *buff, size_t buff_size)
>>>> +static int notrace trace_init_(void *buff, size_t buff_size, bool copy_early,
>>>> +                              bool enable)
>>>>  {
>>>>         int func_count = get_func_count();
>>>>         size_t needed;
>>>> @@ -368,7 +362,7 @@ int notrace trace_init(void *buff, size_t buff_size)
>>>>                 return func_count;
>>>>         trace_save_gd();
>>>>
>>>> -       if (!was_disabled) {
>>>> +       if (copy_early) {
>>>>  #ifdef CONFIG_TRACE_EARLY
>>>>                 ulong used, count;
>>>>                 char *end;
>>>> @@ -394,9 +388,6 @@ int notrace trace_init(void *buff, size_t buff_size)
>>>>                 }
>>>>                 puts("\n");
>>>>                 memcpy(buff, hdr, used);
>>>> -#else
>>>> -               puts("trace: already enabled\n");
>>>> -               return -EALREADY;
>>>>  #endif
>>>>         }
>>>>         hdr = (struct trace_hdr *)buff;
>>>> @@ -419,13 +410,41 @@ int notrace trace_init(void *buff, size_t buff_size)
>>>>         hdr->ftrace_size = (buff_size - needed) / sizeof(*hdr->ftrace);
>>>>         hdr->depth_limit = CONFIG_TRACE_CALL_DEPTH_LIMIT;
>>>>
>>>> -       puts("trace: enabled\n");
>>>> -       trace_enabled = 1;
>>>> +       printf("trace: initialized, %senabled\n", enable ? "" : "not ");
>>>> +       trace_enabled = enable;
>>>>         trace_inited = 1;
>>>>
>>>>         return 0;
>>>>  }
>>>>
>>>> +/**
>>>> + * trace_init() - initialize the tracing system and enable it
>>>> + *
>>>> + * @buff:      Pointer to trace buffer
>>>> + * @buff_size: Size of trace buffer
>>>> + * Return:     0 if ok
>>>> + */
>>>> +int notrace trace_init(void *buff, size_t buff_size)
>>>> +{
>>>> +       /* If traces are enabled already, we may have early traces to copy */
>>>> +       return trace_init_(buff, buff_size, trace_enabled, true);
> 
> This is a global, so you can skip passing it and just check the
> trace_enabled in trace_init_()

Unfortunately not, because trace_clear() needs to be able to invoke trace_init_()
with copy_early = false (we never want to copy the early trace buffer when
coming from the 'trace clear' command).

Thanks,
-- 
Jerome

> 
> Thanks
> /Ilias
>>>> +}
>>>> +
>>>> +/**
>>>> + * trace_clear() - clear accumulated traced data
>>>> + *
>>>> + * May be called with tracing enabled or disabled.
>>>> + */
>>>> +int notrace trace_clear(void)
>>>> +{
>>>> +       bool was_enabled = trace_enabled;
>>>> +
>>>> +       if (trace_enabled)
>>>> +               trace_enabled = 0;
>>>> +       return trace_init_(gd->trace_buff, CONFIG_TRACE_BUFFER_SIZE,
>>>> +                          false, was_enabled);
>>>> +}
>>>> +
>>>>  #ifdef CONFIG_TRACE_EARLY
>>>>  /**
>>>>   * trace_early_init() - initialize the tracing system for early tracing
>>>> --
>>>> 2.43.0
>>>>