1235338 - Make W^X work on arm64

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, defect)

Description

[Jan de Mooij [:jandem]]

Attachment: Patch

Trivial patch to avoid writing back traced Value in TraceDataRelocations if it didn't change. We don't always have writable JIT code there.

Comment 1

[Jan de Mooij [:jandem]]

Comment on attachment 8702241 [details] [diff] [review]
Patch

Adding Luke in case Brian is not around.

Comment 2

[Luke Wagner [:luke]]

Comment on attachment 8702241 [details] [diff] [review]
Patch

Review of attachment 8702241 [details] [diff] [review]:
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::: js/src/jit/arm64/Assembler-arm64.cpp
@@ +573,5 @@
>              layout.asBits = literal;
>              Value v = IMPL_TO_JSVAL(layout);
>              TraceManuallyBarrieredEdge(trc, &v, "ion-masm-value");
> +            if (*literalAddr != JSVAL_TO_IMPL(v).asBits)
> +                *literalAddr = JSVAL_TO_IMPL(v).asBits;

From irc: probably good to comment that this test is necessary since the code is only W for moving/compacting.

Comment 3

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/bdade94c0fd0

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/bdade94c0fd0