From: Mark Rutland <mark.rutland@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Brown <broonie@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-crypto@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH 0/3] arm64: Open code .arch_extension
Date: Wed, 25 Mar 2020 12:03:17 +0000 [thread overview]
Message-ID: <20200325120224.GA34330@C02TD0UTHF1T.local> (raw)
In-Reply-To: <CAMj1kXEogCrLS1o9sQyiXsKZhykfc2kuOssCeME8HyhSnMEFvA@mail.gmail.com>
On Wed, Mar 25, 2020 at 12:54:10PM +0100, Ard Biesheuvel wrote:
> On Wed, 25 Mar 2020 at 12:50, Mark Brown <broonie@kernel.org> wrote:
> > Since BTI is a mandatory feature of v8.5 there is no BTI arch_extension,
> > you can only enable it by moving the base architecture to v8.5. You'd
> > need to use .arch and that feels likely to find us sharp edges to run
> > into.
>
> I think we should talk to the toolchain folks about this. Even if
> .arch_extension today does not support the 'bti' argument, it *is*
> most definitely an architecture extension, even it it is mandatory in
> v8.5 (given that v8.5 is itself an architecture extension).
It certianly seems unfortunate, as it goes against the premise of having
HINT space instructions. Most software will want to enable HINT space
instructions from ARMv8.x but nothing else to ensure binary
compatibility with existing hardware.
I see the same is true for pointer authentication judging by:
https://sourceware.org/binutils/docs/as/AArch64-Extensions.html#AArch64-Extensions
... so worth raising with toolchain folk as a general principle even if
we have to bodge around it for now.
Thanks,
Mark.
next prev parent reply other threads:[~2020-03-25 12:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 11:41 [PATCH 0/3] arm64: Open code .arch_extension Mark Brown
2020-03-25 11:41 ` [PATCH 1/3] arm64: asm: Provide macro to control enabling architecture extensions Mark Brown
2020-03-25 11:41 ` [PATCH 2/3] arm64: lib: Use ARM64_EXTENSIONS() Mark Brown
2020-03-25 11:41 ` [PATCH 3/3] arm64: crypto: " Mark Brown
2020-03-25 11:45 ` [PATCH 0/3] arm64: Open code .arch_extension Ard Biesheuvel
2020-03-25 11:50 ` Mark Brown
2020-03-25 11:54 ` Ard Biesheuvel
2020-03-25 12:01 ` Mark Brown
2020-03-25 12:03 ` Mark Rutland [this message]
2020-03-25 12:24 ` Robin Murphy
2020-04-22 18:00 ` Catalin Marinas
2020-04-23 11:18 ` Mark Brown
2020-04-23 11:59 ` Catalin Marinas
2020-04-23 13:40 ` Catalin Marinas
2020-03-25 12:31 ` Mark Rutland
2020-03-25 13:26 ` Ard Biesheuvel
2020-03-25 13:30 ` Mark Brown
2020-03-25 13:27 ` Mark Brown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200325120224.GA34330@C02TD0UTHF1T.local \
--to=mark.rutland@arm.com \
--cc=ardb@kernel.org \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=ebiggers@google.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-crypto@vger.kernel.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).