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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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[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, missing property will be reported as a warning or an error.
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without the comma the sentence is strange to me.

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@sivan-shani sivan-shani Jul 4, 2025 •
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Here we might want to keep the wording as is, same as it is for

bti-report
cet-report

Which are the same flag type and has the exact same wording.

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Apologies for being a pain. A couple of nits on this line:

I meant (default) at the start of the line. However, looking at bti-report and cet-report above it is probably better to follow the convention and use "is the default," . It was probably that originally; sorry for the noise.

The comma after otherwise looks to be in the wrong position [1]. I think we should follow the wording of bit-report and cet-report.

is the default, linker will not report the missing property otherwise will be reported as a warning or an error.

[1] If I were rewriting with a comma I'd say "report the missing propery, otherwise it will be reported as a warning or an error." However best to stay consistent with the existing wording.

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ack, also for gcs using (default)

.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]
Specifies how the GNU_PROPERTY_AARCH64_FEATURE_1_GCS bit is set in the output ELF file. When set, it indicates support for the Guarded Control Stack (GCS) security feature.
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Use .Cm GNU_PROPERTY_AARCH64_FEATURE_1_GCS

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ack, handled.

.Cm implicit
is the (default) GCS feature bit is inferred from the input object marking.
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reads as "is the GCS feature bit is inferred... "

Suggested change
is the (default) GCS feature bit is inferred from the input object marking.
is the default. GCS feature bit is inferred from the input object marking.

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@sivan-shani sivan-shani Jul 4, 2025 •
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Above is outdated, I believe that new version does not suffer from same ambiguity.

.Cm never
clears the GCS feature bit regardless of input object markings.
.Cm always
set the GCS feature bit regardless of input object markings.
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Suggested change
set the GCS feature bit regardless of input object markings.
sets the GCS feature bit regardless of input object markings.

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ack, changed set->sets

.Pp
.It Cm stack-size Ns = Ns Ar size
Set the main thread's stack size to
.Ar size .
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