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[LLD][Docs] Document -z gcs= option in the man page #146522

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[LLD][Docs] Document -z gcs= option in the man page #146522

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cce8b24
[LLD][Docs] Document `-z gcs` option in the man page
sivan-shani Jul 1, 2025
fb65d4d
[LLD][Docs] Document -z gcs= option in the man page
sivan-shani Jul 1, 2025
0129664
[LLD][Docs] Improve wording and clarity in response to review comments
sivan-shani Jul 2, 2025
68b2552
[LLD][Docs] Align indication of 'default' option, respnd to review co…
sivan-shani Jul 2, 2025
9640c1f
[LLD][Docs] Add .Cm, use 'relocatable files' respond to review comments.
sivan-shani Jul 3, 2025
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14 changes: 14 additions & 0 deletions lld/docs/ld.lld.1
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Original file line number Diff line number Diff line change
Expand Up @@ -798,6 +798,11 @@ Specify how to report the missing GNU_PROPERTY_X86_FEATURE_1_IBT or GNU_PROPERTY
.Cm none
is the default, linker will not report the missing property otherwise will be reported as a warning or an error.
.Pp
.It Cm gcs-report Ns = Ns Ar [none|warning|error]
Specify how to report missing GNU_PROPERTY_AARCH64_FEATURE_1_GCS property. GNU_PROPERTY_AARCH64_FEATURE_1_GCS indicates object file support for the Guarded Control Stack security feature.
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GNU_PROPERTY_AARCH64_FEATURE_1_* properties need to use .Cm

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ack, handled.

.Cm none
is the default, linker will not report the missing property otherwise will be reported as a warning or an error.
.Pp
.It Cm dynamic-undefined-weak
Make undefined weak symbols dynamic when the dynamic symbol table is present, if they are referenced from
relocatable object files and not forced local by symbol visibility or versioning. Do not make them dynamic when
Expand Down Expand Up @@ -953,6 +958,15 @@ disallows overlap.
.It Cm shstk
x86 only, use shadow stack.
.Pp
.It Cm gcs Ns = Ns Ar [implicit|never|always]
Specify how the GCS bit is set. A set GCS bit indicates that the object file supports the Guarded Control Stack security feature.
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I think it would be better to say

Specify how the GNU_PROPERTY_AARCH64_FEATURE_1_GCS feature bit is set in the output ELF file. When set this declares that the ELF file supports the Guarded Control Stack (GCS) security feature.

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ack, wording improved

.Cm implicit
is the default, where the GCS bit is inferred from the input objects.
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From looking at noseparate-code above. I suggest
(default) feature bit is inferred from the input object marking.

I've suggested feature bit rather than GCS bit as we've used the full GNU_PROPERTY_AARCH64_FEATURE_1_GCS feature bit above.

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ack, wording improved

.Cm never
disables the GCS bit regardless of input markings.
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I suggest
clears the feature bit regardless of input object marking.

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ack, wording improved

.Cm always
enables the GCS bit regardless of input markings.
.Pp
.It Cm stack-size Ns = Ns Ar size
Set the main thread's stack size to
.Ar size .
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