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.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: ddeea494a16f3 ("tracing/synthetic: Use union instead of casts")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
/* 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