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

From: Linus Torvalds
Date: Wed Jan 18 2012 - 16:27:02 EST


On Wed, Jan 18, 2012 at 1:04 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>
> Fair enough.  Sigh.  I still think an actual pseudo-register would be
> better.

.. and that breaks existing binaries too, because the indexing is
based on offsets into "struct pt_regs", and while we *could* change
that - leave pt_regs untouched but add a new virtual register - it
would be problematic.

We could add a whole new ptrace() access command (eg
PTRACE_GETSYSTEMREGSET), of course. But that's a lot of effort for
very little gain.

So on the whole, putting it in eflags seemed like the *much* simpler approach.

Linus
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