On Mon, 8 Apr 2019, Thomas Gleixner wrote: > On Mon, 8 Apr 2019, Andy Lutomirski wrote: > > On Sun, Apr 7, 2019 at 11:46 PM Thomas Gleixner <t...@linutronix.de> wrote: > > > > > > On Sun, 7 Apr 2019, Andy Lutomirski wrote: > > > > On Sun, Apr 7, 2019 at 3:44 PM Thomas Gleixner <t...@linutronix.de> > > > > wrote: > > > > > Actually we have: save_stack_trace() > > > > > > > > > > > > > Like I did here: > > > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/log/?h=WIP.x86/stackguards > > > > > > Kinda, but what that code wants is to skip any entry before 'caller'. So > > > we > > > either add something like save_stack_trace_from() which is trivial on x86 > > > because unwind_start() already has an argument to hand in the start of > > > stack or we filter out the entries up to 'caller' in that code. > > > > > > > > Whoops! > > > > I could add a save_stack_trace_from() or I could add a "caller" > > argument to struct stack_trace. Any preference as to which looks > > better? The latter seems a little nicer to me.
Bah, all that sucks. Because 'caller' is comes from __RET_IP__ and is not a pointer to the stack. So this really needs to be a filter which prevents storing an entry _before_ caller is seen on the stack. ftrace and kasan do some post stacktrace filtering as well just different. That's all bonkers. tglx