On Wed, Aug 27, 2014 at 06:55:46AM +0100, AKASHI Takahiro wrote: > On 08/27/2014 02:51 AM, Will Deacon wrote: > > On Fri, Aug 22, 2014 at 01:35:17AM +0100, AKASHI Takahiro wrote: > >> Oops, you're absolutely right. I didn't think of this case. > >> syscall_trace_enter() should not return a syscallno directly, but always > >> return -1 if syscallno < 0. (except when secure_computing() returns with > >> -1) > >> This also implies that tracehook_report_syscall() should also have a > >> return value. > >> > >> Will, is this fine with you? > > > > Well, the first thing that jumps out at me is why this is being done > > completely differently for arm64 and arm. I thought adding the new ptrace > > requests would reconcile the differences? > > I'm not sure what portion of my code you mentioned as "completely different", > but > > 1) > setting x0 to -ENOSYS is necessary because, otherwise, user-issued > syscall(-1) will > return a bogus value when audit tracing is on. > > Please note that, on arm, > not traced traced > ------ ------ > syscall(-1) aborted OOPs(BUG_ON) > syscall(-3000) aborted aborted > syscall(1000) ENOSYS ENOSYS > > So, anyhow, its a bit difficult and meaningless to mimic these invalid cases.
I'm not suggesting we make ourselves bug-compatible with ARM. Instead, I'd rather see a series of patches getting the ARM code working correctly, before we go off doing something different for arm64. > 2) > branching a new label, syscall_trace_return_skip (see entry.S), after > syscall_trace_enter() > is necessary in order to avoid OOPS in audit_syscall_enter() as we discussed. > > Did I make it clear? Sure. So let's fix ARM, then look at the arm64 port after that. I really want to avoid divergence in this area. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
