On Sun, Oct 08, 2017 at 12:44:12PM +0200, Richard Weinberger wrote: > Am Sonntag, 8. Oktober 2017, 12:31:58 CEST schrieb Thomas Meyer: > > UMLs current_thread_info() unconditionally assumes that the top of the stack > > contains the thread_info structure. But on UML the __sanitizer_cov_trace_pc > > function is called for *all* functions! This results in an early crash: > > > > Prevent kcov from using invalid curent_thread_info() data by checking > > the system_state. > > > > Signed-off-by: Thomas Meyer <tho...@m3y3r.de> > > --- > > kernel/kcov.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/kernel/kcov.c b/kernel/kcov.c > > index 3f693a0f6f3e..d601c0e956f6 100644 > > --- a/kernel/kcov.c > > +++ b/kernel/kcov.c > > @@ -56,6 +56,12 @@ void notrace __sanitizer_cov_trace_pc(void) > > struct task_struct *t; > > enum kcov_mode mode; > > > > +#ifdef CONFIG_UML > > + if(!(system_state == SYSTEM_SCHEDULING || > > + system_state == SYSTEM_RUNNING)) > > + return; > > +#endif > > Hmm, and why does it work on all other archs then?
Hi, I guess UML is different then other archs! But to be honest I'm not sure why. I assume that __sanitizer_cov_trace_pc on other archs isn't called that early, or that curent_thread_info returns NULL on other archs when the first task isn't running yet. But as I fail to use/setup the qemu gdb attachment to debug early x86_64 code I can't say exactly why. Maybe someone how knows the inner workings of x86_64 and/or kcov can answer this question! > > Thanks, > //richard >
