Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu

From: Stas Sergeev
Date: Thu Aug 13 2015 - 14:36:17 EST


13.08.2015 21:25, Andy Lutomirski ÐÐÑÐÑ:
On Thu, Aug 13, 2015 at 11:19 AM, Stas Sergeev <stsp@xxxxxxx> wrote:

It is more about selecting the right field for such a flag.
You can select the right field now, and introduce some flag
to it, like SIG_SAVE_SS or whatever. This will fix a regression.
Then, when the TLS time will code, you'll just add SIG_SAVE_FS
flag to the same field, so that they can be ORed.
Oh.

I think the field is obvious: uc_flags.
But Andy, I don't understand...
If we are talking about the field that will in the future also
cover TLS, how can this be uc_flags? By using uc_flags,
how will you control the restoring of FS on signal delivery?

I also thing that all of the
saving should happen automatically, since I still don't see how
anything will break if the kernel starts saving more things. It's the
restore part that's problematic.
OK, so SIG_RESTORE_SS and SIG_RESTORE_FS.
How can those be the part of uc_flags, if we want to
control the restoring _on a signal delivery_?
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