lkml.org 
[lkml]   [2019]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/3] ftrace: fix endianness bug in histogram trigger
On Wed, 18 Dec 2019 08:44:27 +0100
Sven Schnelle <svens@linux.ibm.com> wrote:

> At least on PA-RISC and s390 synthetic histogram triggers are failing
> selftests because trace_event_raw_event_synth() always writes a 64 bit
> values, but the reader expects a field->size sized value. On little endian
> machines this doesn't hurt, but on big endian this makes the reader always
> read zero values.

Tom,

Does this patch look fine to you?

Also, it was only sent to linux-trace-devel. You can see the original
patch here:

https://lore.kernel.org/linux-trace-devel/20191218074427.96184-4-svens@linux.ibm.com/

-- Steve


>
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
> ---
> kernel/trace/trace_events_hist.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index f49d1a36d3ae..f62de5f43e79 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -911,7 +911,26 @@ static notrace void trace_event_raw_event_synth(void *__data,
> strscpy(str_field, str_val, STR_VAR_LEN_MAX);
> n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
> } else {
> - entry->fields[n_u64] = var_ref_vals[var_ref_idx + i];
> + struct synth_field *field = event->fields[i];
> + u64 val = var_ref_vals[var_ref_idx + i];
> +
> + switch (field->size) {
> + case 1:
> + *(u8 *)&entry->fields[n_u64] = (u8)val;
> + break;
> +
> + case 2:
> + *(u16 *)&entry->fields[n_u64] = (u16)val;
> + break;
> +
> + case 4:
> + *(u32 *)&entry->fields[n_u64] = (u32)val;
> + break;
> +
> + default:
> + entry->fields[n_u64] = val;
> + break;
> + }
> n_u64++;
> }
> }

\
 
 \ /
  Last update: 2019-12-20 00:34    [W:0.049 / U:2.964 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site