Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re:[RFC] weird crap with vdso on uml/i386)

[H. Peter Anvin]

On 08/22/2011 06:16 PM, Andrew Lutomirski wrote:
> 
> I suspect that very few things care whether syscall arguments get
> clobbered.  The only way it would matter is if gcc reuses the argument
> in the ecx slot after an inlined syscall later in the same function. 
> Any code that does that is already wrong if the syscall restarts with
> changed ecx or if something like UML changes the syscall argument.
> 

No, the glibc wrapper for the system call Al was looking at used %ecx to
hold a copy of the PIC pointer (normally %ebx)!

	-hpa

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