From: Steven Rostedt <rostedt@goodmis.org>
To: Sven Schnelle <svens@linux.ibm.com>
Cc: linux-trace-devel@vger.kernel.org
Subject: Re: [PATCH 3/3] ftrace: fix endianness bug in histogram trigger
Date: Wed, 18 Dec 2019 10:24:23 -0500 [thread overview]
Message-ID: <20191218102423.755eefdc@gandalf.local.home> (raw)
In-Reply-To: <20191218074427.96184-4-svens@linux.ibm.com>
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.
Does this fix make the other one obsolete?
https://lore.kernel.org/r/20191211110959.2baeb70f@gandalf.local.home
-- 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++;
> }
> }
next prev parent reply other threads:[~2019-12-18 15:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 7:44 ftrace fixes Sven Schnelle
2019-12-18 7:44 ` [PATCH 1/3] selftests/ftrace: fix glob selftest Sven Schnelle
2019-12-19 23:31 ` Steven Rostedt
2019-12-20 7:27 ` Masami Hiramatsu
2019-12-20 7:32 ` Sven Schnelle
2019-12-21 1:23 ` Steven Rostedt
2019-12-18 7:44 ` [PATCH 2/3] samples/trace_printk: wait for IRQ work to finish Sven Schnelle
2019-12-18 7:44 ` [PATCH 3/3] ftrace: fix endianness bug in histogram trigger Sven Schnelle
2019-12-18 15:24 ` Steven Rostedt [this message]
2019-12-18 15:26 ` Sven Schnelle
2019-12-19 23:33 ` Steven Rostedt
2019-12-20 15:25 ` Tom Zanussi
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