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From: Denys Vlasenko <vda.linux@googlemail.com>
To: Jamie Lokier <jamie@shareable.org>
Subject: Re: Compat 32-bit syscall entry from 64-bit task!?
Date: Thu, 26 Jan 2012 02:22:44 +0100
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Cc: Indan Zupancic <indan@nul.nu>, Oleg Nesterov <oleg@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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On Thursday 26 January 2012 02:08, Jamie Lokier wrote:
> Indan Zupancic wrote:
> > > (2) syscall exit compat-ness is known from entry type - no need to indicate it; and
> > > (3) if we would flag syscall entry with an event value in wait status, then syscall
> > > exit will be already distinquisable.
> > 
> > False for execve which messes everything up by changing TID sometimes.
> 
> Is it disambiguated by PTRACE_EVENT_EXEC happening before the execve
> returns, and you knowing the TID always changes to the PID?  I haven't
> yet checked which TID gets the PTRACE_EVENT_EXEC event,

tid change happens before PTRACE_EVENT_EXEC event generation.

-- 
vda