Re: Why is get_current() not const function?

[Andi Kleen <ak@suse.de>]

Jakub Jelinek <jakub@redhat.com> writes:

> E.g. on x86-64,
>         NEW_AUX_ENT(AT_UID, (elf_addr_t) current->uid);
>         NEW_AUX_ENT(AT_EUID, (elf_addr_t) current->euid);
>         NEW_AUX_ENT(AT_GID, (elf_addr_t) current->gid);
>         NEW_AUX_ENT(AT_EGID, (elf_addr_t) current->egid);
> results in 4 movq %gs:0,%rax instructions while one is completely
> enough.
> Anyone remembers why get_current function (on arches which define
> current to get_current()) is not const and why on x86-64

I tried it once. Then spent a day in fixing all the obvious problems
(addings lots of compile barriers to early bootup and the scheduler 
to make it boot again etc.)

In the end I gave up because there were some weird crashes left
and I ran out of time on this one.

Feel free to retry it, but it'll be lots of work I suspect.

-Andi