std_detect: Support run-time detection on aarch64 OpenBSD #1374
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crates/std_detect/src/detect/mod.rs
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| @@ -56,6 +56,12 @@ cfg_if! { | |||
| mod aarch64; | |||
| #[path = "os/freebsd/mod.rs"] | |||
| mod os; | |||
| } else if #[cfg(all(target_os = "openbsd", target_arch = "aarch64", feature = "libc"))] { | |||
| #[allow(dead_code)] | |||
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That module has code that calls the mrs instruction, but it is not used on OpenBSD.
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64: detect: Support run-time detection of FEAT_LSE on aarch64 OpenBSD r=taiki-e a=taiki-e As of nightly-2023-01-23, is_aarch64_feature_detected doesn't support run-time detection of FEAT_LSE on OpenBSD. This patch also supports run-time detection of FEAT_LSE on aarch64 FreeBSD without "std" feature. This patch also adds preliminary support for run-time detection of FEAT_LSE2 and FEAT_LSE128. This is currently only used in tests but will be used in the library in the future. ~~As well as #63, I will send a patch to stdarch later.~~ Filed rust-lang/stdarch#1374. Co-authored-by: Taiki Endo <[email protected]>
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OpenBSD doesn't trap the mrs instruction, but exposes the system registers through sysctl.
openbsd/src@d335af9
So, we can support run-time detection using the register parsing code in os/aarch64.rs (currently used on aarch64 FreeBSD) and sysctl. (See also go's patch that does the same thing as this patch: golang/go@cd54ef1. See also OpenBSD libcrypto patch: openbsd/src@be689f1.)
Tested on aarch64 OpenBSD VM 7.2-current/7.2-stable/7.1-stable.
The following screenshot is from a test on 7.2-current:
On 7.2-stable/7.1-stable, the features referring to ID_AA64PFR0_EL1 returns false because the patch that supports ID_AA64PFR0_EL1 (openbsd/src@c7654cd) is not included: