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

[Pedro Alves]

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?
You can't PTRACE_SINGLESTEP and PTRACE_SYSCALL simultaneously.  Think of
gdb single-stepping all the way for some reason (software watchpoints, for ex.),
while at the same time wanting to catch syscalls.

As Roland suggested, replacing PTRACE_SYSCALL with PTRACE_O_TRACE_SYSCALL_{ENTRY,EXIT}
and PTRACE_EVENT_SYSCALL_{ENTRY,EXIT} would be superior, syscall tracing wise.

-- 
Pedro Alves
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