Messages in this thread | | | Date | Sat, 5 Dec 2015 19:48:40 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] ARM64: Clear out any singlestep state on a ptrace detach operation |
| |
On 12/04, Will Deacon wrote: > > I hacked up a quick patch below (not even compile-tested), but I'm not > sure what to do about hardware {break,watch}points. Some architectures > explicitly clear those on detach, whereas others appear to leave them > alone. Thoughts?
Heh ;)
Please see fab840fc2d542fabcab "ptrace: PTRACE_DETACH should do flush_ptrace_hw_breakpoint(child)".
And the next "revert" commit, 35114fcbe0b9b0fa3f6653a2.
> --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -454,13 +454,20 @@ static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) > return dead; > } > > +#ifndef arch_ptrace_detach > +#define arch_ptrace_detach(child) do { } while (0) > +#endif > + > static int ptrace_detach(struct task_struct *child, unsigned int data) > { > if (!valid_signal(data)) > return -EIO; > > - /* Architecture-specific hardware disable .. */ > - ptrace_disable(child); > + arch_ptrace_detach(child); > + user_disable_single_step(child); > +#ifdef TIF_SYSCALL_EMU > + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); > +#endif > clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
Well, personally I'd prefer to keep the arch-dependent ptrace_disable(), this just looks safer to me. Although I agree that its name is bad and arch_ptrace_detach() looks much better.
Oleg.
| |