| Message ID | 20230908160157.1152301f@gandalf.local.home (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | tracing/synthetic: Fix order of struct trace_dynamic_info | expand |
On Fri, 8 Sep 2023 16:01:57 -0400 Steven Rostedt <rostedt@goodmis.org> wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > To make handling BIG and LITTLE endian better the offset/len of dynamic > fields of the synthetic events was changed into a structure of: > > struct trace_dynamic_info { > #ifdef CONFIG_CPU_BIG_ENDIAN > u16 offset; > u16 len; > #else > u16 len; > u16 offset; > #endif > }; > > to replace the manual changes of: > > data_offset = offset & 0xffff; > data_offest = len << 16; > > But if you look closely, the above is: > > <len> << 16 | offset > > Which in little endian would be in memory: > > offset_lo offset_hi len_lo len_hi > > and in big endian: > > len_hi len_lo offset_hi offset_lo > > Which if broken into a structure would be: > > struct trace_dynamic_info { > #ifdef CONFIG_CPU_BIG_ENDIAN > u16 len; > u16 offset; > #else > u16 offset; > u16 len; > #endif > }; > > Which is the opposite of what was defined. > > Fix this and just to be safe also add "__packed". Good catch! This looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Link: https://lore.kernel.org/all/20230908154417.5172e343@gandalf.local.home/ > > Cc: stable@vger.kernel.org > Fixes: ddeea494a16f3 ("tracing/synthetic: Use union instead of casts") > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > include/linux/trace_events.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h > index 12f875e9e69a..21ae37e49319 100644 > --- a/include/linux/trace_events.h > +++ b/include/linux/trace_events.h > @@ -62,13 +62,13 @@ void trace_event_printf(struct trace_iterator *iter, const char *fmt, ...); > /* Used to find the offset and length of dynamic fields in trace events */ > struct trace_dynamic_info { > #ifdef CONFIG_CPU_BIG_ENDIAN > - u16 offset; > u16 len; > + u16 offset; > #else > - u16 len; > u16 offset; > + u16 len; > #endif > -}; > +} __packed; > > /* > * The trace entry - the most basic unit of tracing. This is what > -- > 2.40.1 >
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 12f875e9e69a..21ae37e49319 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -62,13 +62,13 @@ void trace_event_printf(struct trace_iterator *iter, const char *fmt, ...); /* Used to find the offset and length of dynamic fields in trace events */ struct trace_dynamic_info { #ifdef CONFIG_CPU_BIG_ENDIAN - u16 offset; u16 len; + u16 offset; #else - u16 len; u16 offset; + u16 len; #endif -}; +} __packed; /* * The trace entry - the most basic unit of tracing. This is what