Implement gic_splraise and the gic_splx fast path in asm (armv8).

Add missing insn barrier

Make _splraise/_spllower/splx functions available to modules again.

gic_splx: performance optimizations

Avoid any kind of register access (DAIF, PMR, etc), barriers, and atomic
operations in the common case where no interrupt fires between spl being
raised and lowered.

This introduces a per-CPU return address (ci_splx_restart) used by the
vector handler to restart a sequence in splx that compares the new ipl
with the per-CPU hardware priority state stored in ci_hwpl.

Use custom spl funcs for GIC and avoid unnecessary pmr register accesses
in splx.

Add missing insn barrier

Make _splraise/_spllower/splx functions available to modules again.

gic_splx: performance optimizations

Avoid any kind of register access (DAIF, PMR, etc), barriers, and atomic
operations in the common case where no interrupt fires between spl being
raised and lowered.

This introduces a per-CPU return address (ci_splx_restart) used by the
vector handler to restart a sequence in splx that compares the new ipl
with the per-CPU hardware priority state stored in ci_hwpl.

Use custom spl funcs for GIC and avoid unnecessary pmr register accesses
in splx.

Make _splraise/_spllower/splx functions available to modules again.

gic_splx: performance optimizations

Avoid any kind of register access (DAIF, PMR, etc), barriers, and atomic
operations in the common case where no interrupt fires between spl being
raised and lowered.

This introduces a per-CPU return address (ci_splx_restart) used by the
vector handler to restart a sequence in splx that compares the new ipl
with the per-CPU hardware priority state stored in ci_hwpl.

Use custom spl funcs for GIC and avoid unnecessary pmr register accesses
in splx.

gic_splx: performance optimizations

Avoid any kind of register access (DAIF, PMR, etc), barriers, and atomic
operations in the common case where no interrupt fires between spl being
raised and lowered.

This introduces a per-CPU return address (ci_splx_restart) used by the
vector handler to restart a sequence in splx that compares the new ipl
with the per-CPU hardware priority state stored in ci_hwpl.

Use custom spl funcs for GIC and avoid unnecessary pmr register accesses
in splx.

Use custom spl funcs for GIC and avoid unnecessary pmr register accesses
in splx.