arm: Implement kernel IFUNC

[mmel]

Summary

Add kernel ifunc support on arm.

MFC after : 3 weeks

[kib]

sys/arm/arm/machdep.c

450

Isn't it too early? I put the sched_instance_select() after init_param1(). This is not strictly necessary now, but makes some amount of tuning knobs initialized before scheduler is selected.

sys/arm/include/ifunc.h

4

You should at least add your copyright there, if not replacing mine/FF altogether.

Also we normally put SPDX tag instead of the license text in modern times.

sys/conf/kern.pre.mk

122

Now that only riscv is the exempt, perhaps change this to check that MACHINE_CPUARCH != riscv instead?

sys/kern/link_elf.c

2044

Similarly, #ifndef riscv ? No strong opinion.

[andrew]

sys/arm/arm/machdep.c

450

It's before init_param1 on amd64, arm64, and riscv. It might be difficult to move later on architectures where the mem* functions are an ifunc.

[kib]

sys/arm/arm/machdep.c

450

I open-coded several str* functions in sched_instance_select() for this reason.

[mmel]

sys/arm/arm/machdep.c

450

It's the target. I want to use ifunc later also for cache operations and maily for SW/HW divide. So these must be resolved ASAP.

sys/arm/include/ifunc.h

4

I copied it from x86 with minimal changes. It's no problem to steal it :)

sys/conf/kern.pre.mk

122

Oki, I'll change it before commit.

sys/kern/link_elf.c

2044

ditto

[kib]

sys/arm/include/ifunc.h

4

Please do fix this.
Otherwise, I see no issues with the patch.