[lld][AArch64][Build Attributes] Add support for AArch64 Build Attributes #142637
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Previously, the AArch64 PAuth ABI core values were stored as an ArrayRef<uint8_t>, introducing unnecessary indirection. This patch replaces the ArrayRef with two explicit uint64_t fields: aarch64PauthAbiPlatform and aarch64PauthAbiVersion. This simplifies the representation and improves readability. No functional change intended, aside from improved error messages.
sivan-shani
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davemgreen,
nasherm,
ostannard,
smithp35 and
stuij
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Just one quick comment on the functional side (mapping PAuth BuildAttributes 0, 1 to an explicit GNU properties of 0, 0).
Will keep looking to see if I can spot anything else.
lld/ELF/InputFiles.cpp
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There's a bit in the BuildAttributes spec to handle this case. Starting at https://github.com/ARM-software/abi-aa/pull/230/files#diff-9563b0c9eccaf2fd9c6dd704c6ef00fbe7b531657e220c0324523391da355d1cR1030 and also https://github.com/ARM-software/abi-aa/pull/230/files#diff-9563b0c9eccaf2fd9c6dd704c6ef00fbe7b531657e220c0324523391da355d1cR1053
Essentially a build attributes of TagPlatform 0, TagSchema 1 maps to an explicit GNU Properties section of 0, 0.
I think the simplest way of handling this would be to change TagPlatform 0, TagSchema 1 (which would pass the if test) to an aarch64PauthAbiCoreInfo of (0, 0).
Would likely need the comment updating. Something like:
Build Attributes default to a value of 0 when not present. A (TagPlatform, TagSchema) of (0, 0) maps to no PAuth property present. A (TagPlatform, TagSchema) of (0, 1) maps to an explicit PAuth property of platform = 0, version = 0.
…utes This patch enables lld to read AArch64 Build Attributes and convert them into GNU Properties. Changes: - Parses AArch64 Build Attributes from input object files. - Converts known attributes into corresponding GNU Properties. - Merges attributes when linking multiple objects.
According to the Arm BuildAttributes specification, a (TagPlatform, TagSchema)
of (0, 1) corresponds to an explicit property with platform = 0 and version = 0 ('Invalid').
Update LLD to handle this case by mapping it to aarch64PauthAbiCoreInfo = {0, 0}.
Update comment to clarify default behavior and mapping.
Spec reference:
https://github.com/ARM-software/abi-aa/pull/230/files#r1030
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This patch enables lld to read AArch64 Build Attributes and convert them into GNU Properties.
Changes: