Re: Compat 32-bit syscall entry from 64-bit task!?

[Denys Vlasenko]

On Wednesday 25 January 2012 21:20, Pedro Alves wrote:
> On 01/25/2012 07:36 PM, Oleg Nesterov wrote:
> > 
> > Not sure this is really better, but there is another idea. Currently we
> > have PTRACE_O_TRACESYSGOOD to avoid the confusion with the real SIGTRAP.
> > Perhaps we can add PTRACE_O_TRACESYS_VERY_GOOD (or we can look at
> > PT_SEIZED instead) and report TS_COMPAT via ptrace_report_syscall ?
> 
> May I beg to don't rely on PTRACE_SYSCALL for anything new?

This doesn't *add* anything new. All the same ptrace stops will happen
at exactly the same moments. No new stops added. We only add a value
into upper half of waitpid status: (status >> 16) used to be 0
on syscall entry. Now it will be PTRACE_EVENT_SYSCALL_ENTRY[1].
That's all.

> You can't PTRACE_SINGLESTEP and PTRACE_SYSCALL simultaneously.

This is an orthogonal problem.

-- 
vda
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