arm64: pagezero improvement

[der_semihalf.com]

Summary

This change has been provided to improve pagezero call performance.

[kib]

Wouldn't it be (much) cleaner to select one of two implementations (dc/stp) e.g. by function pointer ?

sys/arm64/arm64/support.S

300 ↗

(On Diff #14608)

What is the purpose of this calculation ? pagezero must always be called with the page-aligned address.

[der_semihalf.com]

In D5741#122931, @kib wrote:

Wouldn't it be (much) cleaner to select one of two implementations (dc/stp) e.g. by function pointer ?

Yes it would.

sys/arm64/arm64/support.S

300 ↗

(On Diff #14608)

Note taken. Will be removed.

[der_semihalf.com]

All of reviewers' comments have been applied.

[wma]

sys/arm64/arm64/machdep.c

113 ↗

(On Diff #14701)

This should be defined as extern in some header, machdep.h looks appropriate.

828 ↗

(On Diff #14701)

Extra line.

sys/arm64/arm64/pmap.c

251 ↗

(On Diff #14701)

That should go to machdep.c

[der_semihalf.com]

All reviewers' comments have been applited.

[andrew]

sys/arm64/arm64/machdep.c

113 ↗

(On Diff #14701)

It's ok like that, we only access this directly from this file. If the implementation was in a .c file it should be in a header, however a comment pointing to the .S file will be useful.

[kib]

There seems to be some issues with spaces/tabs between instructions and operands.

Otherwise looks good.

[der_semihalf.com]

In D5741#123261, @kib wrote:

There seems to be some issues with spaces/tabs between instructions and operands.

It seems that they only appear here as in vim the spacing/tabs looks exactly as in implementations of all other functions.

[der_semihalf.com]

Provided comment as requested.