linuxkpi: Add `strtomem()` and `strtomem_pad()`

[dumbbell]

Summary

The DRM generic code started to use strtomem_pad() in Linux 6.11.

This is part of the update of DRM drivers to Linux 6.11.

Sponsored by: The FreeBSD Foundation

[emaste]

sys/compat/linuxkpi/common/include/linux/string.h

311

what is this 4-arg memcpy?

[dumbbell]

Fix use of memcpy() as reported by @emaste

[dumbbell]

sys/compat/linuxkpi/common/include/linux/string.h

311

Too much copy-paste

[bz]

sys/compat/linuxkpi/common/include/linux/string.h

307

Reading the description it sounds like (here and down) dest should use ARRAY_SIZE (nitems)?

[dumbbell]

sys/compat/linuxkpi/common/include/linux/string.h

307

So you suggest:

size_t dstlen = ARRAY_SIZE(dst);
``` instead, is that correct?

I’m not sure i get the difference. Is it semantically more correct?

In this case, should `ARRAY_SIZE()` be used for `srclen` too?

[bz]

sys/compat/linuxkpi/common/include/linux/string.h

307

Only for dstlen as dst that is supposed to be a Pointer of destination character array (marked as __nonstring) according to the documentation. Making in ARRAY_SIZE I hope will catch other possible kinds of buffers--while Linux should catch that already for drivers I would hope, in case we use this internally in LinuxKPI it's just to be saver.