nss-3.90 breaks w/ earlier x86-64 CPUs (SIGILL)

nss-3.90 breaks w/ earlier x86-64 CPUs (SIGILL)

[Sam James]

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nss-3.90 unconditionally uses adcxq on x86-64 which breaks on <
Broadwell.

See https://bugzilla.mozilla.org/show_bug.cgi?id=1836925. There's
an upstream patch to just rip it out for now, but you need a
pre-requisite patch too.

Patches:
1. https://github.com/nss-dev/nss/commit/c07c4e073d95a25343cbf56b4a830a71e432869e
2. https://phabricator.services.mozilla.com/D180068?download=true

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Re: nss-3.90 breaks w/ earlier x86-64 CPUs (SIGILL)

[John Paul Adrian Glaubitz]

Hi Sam!

On Tue, 2023-06-06 at 22:12 +0100, Sam James wrote:
> nss-3.90 unconditionally uses adcxq on x86-64 which breaks on <
> Broadwell.

Thanks for the heads-up! It's unfortunately a common problem with
the Mozilla codebase and has happened multiple times before.

Someone contributes new code to accelerate functionality using new
processor features and then they completely forget to guard this
code properly so it isn't used unconditionally.

Also, Mozilla's build system is rather complex which means adding
such guards as an external contributor is quite time consuming,
been there, done that.

Adrian

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