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".

Link: https://lore.kernel.org/all/20230908154417.5172e343@gandalf.local.home/ Link: https://lore.kernel.org/linux-trace-kernel/20230908163929.2c25f3dc@gandalf.l...

Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Sven Schnelle svens@linux.ibm.com 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