On Thu, 28 Dec 2017 16:26:07 +0000
Ard Biesheuvel [off-list ref] wrote:

On 28 December 2017 at 16:19, Steven Rostedt [off-list ref] wrote:

quoted

On Wed, 27 Dec 2017 08:50:33 +0000
Ard Biesheuvel [off-list ref] wrote:
 

quoted

 static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
 {
-     return entry->code;
+     return (jump_label_t)&entry->code + entry->code;  

I'm paranoid about doing arithmetic on abstract types. What happens in
the future if jump_label_t becomes a pointer? You will get a different
result.
 

In general, I share your concern. In this case, however, jump_label_t
is typedef'd three lines up and is never used anywhere else.

I would agree if this was in a .c file, but it's in a header file,
which causes me to be more paranoid.

quoted

Could we switch these calculations to something like:

        return (jump_label_t)((long)&entrty->code + entry->code);
 

jump_label_t is local to this .h file, so it can be defined as u32 or
u64 depending on the word size. I don't mind adding the extra cast,
but I am not sure if your paranoia is justified in this particular
case. Perhaps we should just use 'unsigned long' throughout?

Actually, that may be better. Have the return value be jump_label_t,
but the cast be "unsigned long". That way it should always work.

static inline jump_label_t jump_entry_code(...)
{
	return (unsigned long)&entry->code + entry->code;
}


-- Steve