[libpas] Implement primary support for MTE

[Achierius]

f3dd285

[libpas] Implement primary support for MTE
https://bugs.webkit.org/show_bug.cgi?id=299488
rdar://161273712

Reviewed by Daniel Liu.

As announced on September 9th, the SoCs used in the next generation of
iPhones will include support for ARM'S Memory Tagging Extension
functionality. As part of Apple's MIE (Memory Integrity Enforcement)
feature, libpas should thus implement support for MTE and related
memory-safety functionality to ensure that WebKit is up to par with the
new memory safety standards set by the rest of the system.

In particular, this patch ensures that when possible we allocate memory
with backing MTE tag pages and tag allocations made within them prior to
returning allocation memory to the caller. Not all memory can be tagged
this way: in particular, objects >= 32K and objects which may be
referenced via compact pointers cannot be MTE tagged. There are other
exceptions as well, depending on process/object-type/platform.
It also implements a variety of hardening strategies to further
strengthen the feature and prevent certain well-known kinds of attacks.

Trying this again, since the previous attempt caused build breakages
in certain configurations.

Canonical link: https://commits.webkit.org/300960@main

ec076f6

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	❌ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	❌ 🛠 jsc-armv7
	✅ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash f7641af)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	❌ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	❌ 🛠 jsc-armv7
	✅ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 12c8dce)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
⏳ 🧪 style	⏳ 🛠 ios	⏳ 🛠 mac	⏳ 🛠 wpe	⏳ 🛠 win	✅ 🛠 ios-apple
⏳ 🧪 bindings	⏳ 🛠 ios-sim	⏳ 🛠 mac-AS-debug	⏳ 🧪 wpe-wk2	⏳ 🧪 win-tests	❌ 🛠 mac-apple
⏳ 🧪 webkitperl	⏳ 🧪 ios-wk2	⏳ 🧪 api-mac	⏳ 🧪 api-wpe		✅ 🛠 vision-apple
⏳ 🧪 webkitpy	⏳ 🧪 ios-wk2-wpt	⏳ 🧪 mac-wk1	⏳ 🛠 wpe-cairo
⏳ 🛠 🧪 jsc	⏳ 🧪 api-ios	⏳ 🧪 mac-wk2	⏳ 🛠 gtk
⏳ 🛠 🧪 jsc-arm64	⏳ 🛠 vision	⏳ 🧪 mac-AS-debug-wk2	⏳ 🧪 gtk-wk2
⏳ 🧪 services	⏳ 🛠 vision-sim	⏳ 🧪 mac-wk2-stress	⏳ 🧪 api-gtk
	⏳ 🧪 vision-wk2	⏳ 🧪 mac-intel-wk2	⏳ 🛠 playstation
	⏳ 🛠 tv	⏳ 🛠 mac-safer-cpp	⏳ 🛠 jsc-armv7
	⏳ 🛠 tv-sim		⏳ 🧪 jsc-armv7-tests
	⏳ 🛠 watch
	⏳ 🛠 watch-sim

[danlliu]

r=me

[webkit-early-warning-system]

EWS run on current version of this PR (hash ec076f6)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	❌ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	❌ 🛠 jsc-armv7
	✅ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 300960@main (f3dd285): https://commits.webkit.org/300960@main

Reviewed commits have been landed. Closing PR #51633 and removing active labels.