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

[Jerome Forissier]

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);
>> +}
>> +
>> +/**
>> + * 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
>>