Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch V3 01/13] entry: Provide generic syscall entry functionality | Date | Sat, 18 Jul 2020 16:16:26 +0200 |
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Andy Lutomirski <luto@kernel.org> writes: > On Fri, Jul 17, 2020 at 12:29 PM Thomas Gleixner <tglx@linutronix.de> wrote: >> The alternative is to play nasty games with TIF_IA32, TIF_ADDR32 and >> TIF_X32 to free up bits for 32bit and make the flags field 64 bit on 64 >> bit kernels, but I prefer to do the above seperation. > > I'm all for cleaning it up, but I don't think any nasty games would be > needed regardless. IMO at least the following flags are nonsense and > don't belong in TIF_anything at all: > > TIF_IA32, TIF_X32: can probably be deleted. Someone would just need > to finish the work. > TIF_ADDR32: also probably removable, but I'm less confident. > TIF_FORCED_TF: This is purely a ptrace artifact and could easily go > somewhere else entirely. > > So getting those five bits back would be straightforward. > > FWIW, TIF_USER_RETURN_NOTIFY is a bit of an odd duck: it's an > entry/exit word *and* a context switch word. The latter is because > it's logically a per-cpu flag, not a per-task flag, and the context > switch code moves it around so it's always set on the running task.
Gah, I missed the context switch thing of that. That stuff is hideous.
Thanks,
tglx
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