Re: [PATCH] Set TIF_IRET in more places

[Linus Torvalds]

On Mon, 6 Jan 2003, Luca Barbieri wrote:
> 
> 1. vfork seems to not set any TIF_ flags so a ptracer setting regs
> while a vforking task is stopped in ptrace_notify called from vfork
> would result in clobbered %ecx and %edx.

vfork and clone do not work at all with sysenter due to user stack issues.
We should document that (it's already de-facto documented in glibc, but it 
should be explicitly documented somewhere).

Btw, the vfork/clone problems aren't sysenter-specific per se: they are 
really a generic problem with any non-inlined system call mechanism. In 
particular, vfork() really cannot afford to have a stack frame.

> 2. A ptracer could use %ecx or %edx to pass information to signal
> handlers and this would not work with the current [rt_]sigsuspend.

Yes. Although I don't see why it should matter, really. 

		Linus