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check before test for hardware capabilites in bits 32~63 of usize #146323

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Merged
merged 4 commits into from
Sep 12, 2025
+44 −33
Merged

check before test for hardware capabilites in bits 32~63 of usize #146323

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c776fbf
check before test for hardware capabilites in bits 32~63 of usize
h3fang Sep 8, 2025
be284b6
add some comments to clarify the fix
h3fang Sep 8, 2025
de359c5
fix typos in comment
h3fang Sep 8, 2025
4c849c7
fix typo in comment
h3fang Sep 12, 2025
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77 changes: 44 additions & 33 deletions library/std_detect/src/detect/os/linux/aarch64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -140,7 +140,7 @@ struct AtHwcap {
impl From<auxvec::AuxVec> for AtHwcap {
/// Reads AtHwcap from the auxiliary vector.
fn from(auxv: auxvec::AuxVec) -> Self {
AtHwcap {
let mut cap = AtHwcap {
fp: bit::test(auxv.hwcap, 0),
asimd: bit::test(auxv.hwcap, 1),
// evtstrm: bit::test(auxv.hwcap, 2),
Expand Down Expand Up @@ -207,39 +207,50 @@ impl From<auxvec::AuxVec> for AtHwcap {
// smef32f32: bit::test(auxv.hwcap2, 29),
smefa64: bit::test(auxv.hwcap2, 30),
wfxt: bit::test(auxv.hwcap2, 31),
// ebf16: bit::test(auxv.hwcap2, 32),
// sveebf16: bit::test(auxv.hwcap2, 33),
cssc: bit::test(auxv.hwcap2, 34),
// rprfm: bit::test(auxv.hwcap2, 35),
sve2p1: bit::test(auxv.hwcap2, 36),
sme2: bit::test(auxv.hwcap2, 37),
sme2p1: bit::test(auxv.hwcap2, 38),
// smei16i32: bit::test(auxv.hwcap2, 39),
// smebi32i32: bit::test(auxv.hwcap2, 40),
smeb16b16: bit::test(auxv.hwcap2, 41),
smef16f16: bit::test(auxv.hwcap2, 42),
mops: bit::test(auxv.hwcap2, 43),
hbc: bit::test(auxv.hwcap2, 44),
sveb16b16: bit::test(auxv.hwcap2, 45),
lrcpc3: bit::test(auxv.hwcap2, 46),
lse128: bit::test(auxv.hwcap2, 47),
fpmr: bit::test(auxv.hwcap2, 48),
lut: bit::test(auxv.hwcap2, 49),
faminmax: bit::test(auxv.hwcap2, 50),
f8cvt: bit::test(auxv.hwcap2, 51),
f8fma: bit::test(auxv.hwcap2, 52),
f8dp4: bit::test(auxv.hwcap2, 53),
f8dp2: bit::test(auxv.hwcap2, 54),
f8e4m3: bit::test(auxv.hwcap2, 55),
f8e5m2: bit::test(auxv.hwcap2, 56),
smelutv2: bit::test(auxv.hwcap2, 57),
smef8f16: bit::test(auxv.hwcap2, 58),
smef8f32: bit::test(auxv.hwcap2, 59),
smesf8fma: bit::test(auxv.hwcap2, 60),
smesf8dp4: bit::test(auxv.hwcap2, 61),
smesf8dp2: bit::test(auxv.hwcap2, 62),
// pauthlr: bit::test(auxv.hwcap2, ??),
..Default::default()
};

// Hardware capabilities from bits 32 to 63 should only
// be tested on LP64 targets with 64 bits `usize`.
// On ILP32 targets like `aarch64-unknown-linux-gnu_ilp32`,
// these hardware capabilities will default to `false`.
// https://github.com/rust-lang/rust/issues/146230
#[cfg(target_pointer_width = "64")]
{
Comment on lines +218 to +219
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This should at least get a comment, because I think it's quite reasonable to assume that aarch64 implies 64-bit pointers.

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also now you're basically saying that the features in this block cannot be queried for on ilp32, is that correct?

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Ok, I will add some comment to clarify it.

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also now you're basically saying that the features in this block cannot be queried for on ilp32, is that correct?

Yes, the libc::getauxval returns 32 bit c_ulong for aarch64 ILP32 target.

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@h3fang h3fang Sep 8, 2025 •
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also now you're basically saying that the features in this block cannot be queried for on ilp32, is that correct?

Well, to be more accurate, they can be queried, but the values will all be false.

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This should at least get a comment, because I think it's quite reasonable to assume that aarch64 implies 64-bit pointers.

I have added some comments to clarify it.

// cap.ebf16: bit::test(auxv.hwcap2, 32);
// cap.sveebf16: bit::test(auxv.hwcap2, 33);
cap.cssc = bit::test(auxv.hwcap2, 34);
// cap.rprfm: bit::test(auxv.hwcap2, 35);
cap.sve2p1 = bit::test(auxv.hwcap2, 36);
cap.sme2 = bit::test(auxv.hwcap2, 37);
cap.sme2p1 = bit::test(auxv.hwcap2, 38);
// cap.smei16i32 = bit::test(auxv.hwcap2, 39);
// cap.smebi32i32 = bit::test(auxv.hwcap2, 40);
cap.smeb16b16 = bit::test(auxv.hwcap2, 41);
cap.smef16f16 = bit::test(auxv.hwcap2, 42);
cap.mops = bit::test(auxv.hwcap2, 43);
cap.hbc = bit::test(auxv.hwcap2, 44);
cap.sveb16b16 = bit::test(auxv.hwcap2, 45);
cap.lrcpc3 = bit::test(auxv.hwcap2, 46);
cap.lse128 = bit::test(auxv.hwcap2, 47);
cap.fpmr = bit::test(auxv.hwcap2, 48);
cap.lut = bit::test(auxv.hwcap2, 49);
cap.faminmax = bit::test(auxv.hwcap2, 50);
cap.f8cvt = bit::test(auxv.hwcap2, 51);
cap.f8fma = bit::test(auxv.hwcap2, 52);
cap.f8dp4 = bit::test(auxv.hwcap2, 53);
cap.f8dp2 = bit::test(auxv.hwcap2, 54);
cap.f8e4m3 = bit::test(auxv.hwcap2, 55);
cap.f8e5m2 = bit::test(auxv.hwcap2, 56);
cap.smelutv2 = bit::test(auxv.hwcap2, 57);
cap.smef8f16 = bit::test(auxv.hwcap2, 58);
cap.smef8f32 = bit::test(auxv.hwcap2, 59);
cap.smesf8fma = bit::test(auxv.hwcap2, 60);
cap.smesf8dp4 = bit::test(auxv.hwcap2, 61);
cap.smesf8dp2 = bit::test(auxv.hwcap2, 62);
// cap.pauthlr = bit::test(auxv.hwcap2, ??);
}
cap
}
}

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