On Mon, 2 May 2016, Jiri Kosina wrote:

quoted

FWIW, I just tried this:

static bool is_entry_text(unsigned long addr)
{
    return addr >= (unsigned long)__entry_text_start &&
        addr < (unsigned long)__entry_text_end;
}

it works.  So the entry code is already annotated reasonably well :)

I just hacked it up here:

https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=stack&id=085eacfe0edfc18768e48340084415dba9a6bd21

and it seems to work, at least for page faults.  A better
implementation would print out the entire contents of pt_regs so that
people reading the stack trace will know the registers at the time of
the exception, which might be helpful.

Sorry for being dense, but how do you distinguish here between a "real" 
kernel entry, that pushes pt_regs, and any "non-entry" function call that 
passes pt_regs around?

Umm, actually, the more tricky part is the other way around -- how do you 
make sure that whenever you are calling out from a code between 
__entry_text_start and __entry_text_end, pt_regs will be at the place 
you're looking for it? How's that guaranteed?

Thanks,

-- 
Jiri Kosina
SUSE Labs