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

[Ilias Apalodimas]

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

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
>