Messages in this thread | | | Date | Wed, 1 Aug 2012 16:01:21 +0200 | From | Oleg Nesterov <> | Subject | Re: Q: user_enable_single_step() && update_debugctlmsr() |
| |
On 08/01, Sebastian Andrzej Siewior wrote: > > On 08/01/2012 03:46 PM, Oleg Nesterov wrote: > >>>> But, worse, isn't it wrong? Suppose that debugger switches to >>>> another TIF_SINGLESTEP&& !TIF_BLOCKSTEP task, in this case >>>> we "leak" DEBUGCTLMSR_BTF, no? >>> >>> __switch_to_xtra() should notice the difference in the TIF_BLOCKSTEP >>> flag and disable it. >> >> And how it can notice the difference if there is no difference? >> >> (unless, of course debugger is TIF_BLOCKSTEP'ed). > > Yes. enable_step() sets DEBUGCTLMSR_BTF along with TIF_BLOCKSTEP. > kprobes checks the same flag before touching DEBUGCTLMSR_BTF.
It seems that you replied to the wrong email or I am confused ;)
Let's ignore kprobes here.
Oleg.
| |