Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 86f52ba2f2c1597d4d4c7450c370c8b77c38cd9f
https://github.com/WebKit/WebKit/commit/86f52ba2f2c1597d4d4c7450c370c8b77c38cd9f
Author: Marcus Plutowski <[email protected]>
Date: 2026-09-10 (Thu, 10 Sep 2026)
Changed paths:
M Source/bmalloc/libpas/src/libpas/pas_mte_config.c
M Source/bmalloc/libpas/src/libpas/pas_mte_config.h
M Source/bmalloc/libpas/src/libpas/pas_runtime_config.h
Log Message:
-----------
[libpas] Replace MTE enablement bool with a tri-state
https://bugs.webkit.org/show_bug.cgi?id=323820
rdar://187058868
Reviewed by Yusuke Suzuki.
pas_runtime_config lives in the reserved slots at the start of WTF's
g_config, which is zero-initialized at load time. Previously the MTE
enablement bit was a bool with 0 meaning either uninitialized or
not enabled. However, this means that in order to ensure that the
enablement-state was initialized, a consumer would need to call through
the out-of-line pas_mte_is_mte_enabled function which calls into
dispatch_once_f and is thus too heavy to have on the malloc hot path.
This patch replaces the enablement bool with a tristate so that
consumers can perform a relaxed load to determine whether or not they
need to go down the slow path, now appropriately renamed
pas_mte_is_mte_enabled_slow(). The tristate can be read with a relaxed
load because the slow-path uses dispatch_once_f to ensure that multiple
callers don't actually initialize libpas more than once, and the state
will only be set once.
In the new model, the consumer-facing pas_mte_is_mte_enabled() function
is an inlineable hot-path, while pas_mte_is_mte_enabled_slow() handles
the dispatch_once_f.
* Source/bmalloc/libpas/src/libpas/pas_runtime_config.h: add pas_mte_state,
replace pas_runtime_config::enabled with mte_state
* Source/bmalloc/libpas/src/libpas/pas_mte_config.h:
(pas_mte_is_mte_enabled_unchecked): report the field as-is, for libpas' own use
(pas_mte_is_mte_disabled_unchecked):
(pas_mte_is_mte_enabled): new inlineable entry point handling all three states
* Source/bmalloc/libpas/src/libpas/pas_mte_config.c:
(pas_mte_do_initialization): accumulate locally, publish with a release store
(pas_mte_is_enabled):
(pas_report_config):
(pas_mte_is_mte_enabled_slow): Renamed from pas_mte_is_mte_enabled.
(pas_mte_is_mte_enabled): Deleted.
Canonical link: https://commits.webkit.org/320852@main
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