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Unless I'm missing something egregious, the jmp cache is only every
populated with a valid entry by the same thread that reads the cache.
Therefore, the contents of any valid entry are always consistent and
there is no need for any acquire/release magic.
Indeed ->tb has to be accessed with atomics, because concurrent
invalidations would otherwise cause data races. But ->pc is only ever
accessed by one thread, and accesses to ->tb and ->pc within tb_lookup
can never race with another tb_lookup. While the TranslationBlock
(especially the flags) could be modified by a concurrent invalidation,
store-release and load-acquire operations on the cache entry would
not add any additional ordering beyond what you get from performing
the accesses within a single thread.
Because of this, there is really nothing to win in splitting the CF_PCREL
and !CF_PCREL paths. It is easier to just always use the ->pc field in
the jump cache.
I noticed this while working on splitting commit
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| hvf | ||
| kvm | ||
| qtest | ||
| stubs | ||
| tcg | ||
| xen | ||
| accel-blocker.c | ||
| accel-system.c | ||
| accel-system.h | ||
| accel-target.c | ||
| accel-user.c | ||
| dummy-cpus.c | ||
| Kconfig | ||
| meson.build | ||