Re: Merging ptrace branch into mainline

From: Tejun Heo
Date: Fri Jul 22 2011 - 09:39:16 EST

On Fri, Jul 22, 2011 at 01:40:36PM +0200, Denys Vlasenko wrote:
> On Fri, Jul 22, 2011 at 12:30 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> To what cases of ptrace stops is this applicable?
> I thought with PTRACE_O_TRACESYSGOOD the problem with SIGTRAP
> being special under strace is dealt with: now both user-sent
> SIGTRAPs and ones generated by int3 instruction are handled correctly
> in current strace git.
> Is it about single-stepping? Strace doesn't use PTRACE_SIGLESTEP,
> and I didn't have the need yet to familiarize myself with it.
> Does it generate SIGTRAP?

Single step and breakpoints use SIGTRAP and there are some variances
on the information being reported depending on archs and IIRC it isn't
always possible to discern those debug traps from kill(SIGTRAP)'s from
userland. I think cleaning up what information is reported via
siginfo on debug traps should resolve this too.


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