From: Mark Rutland <mark.rutland@arm.com>
To: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Kees Cook <keescook@chromium.org>,
Sami Tolvanen <samitolvanen@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: fix function types in COND_SYSCALL
Date: Fri, 13 Sep 2019 12:33:55 +0100 [thread overview]
Message-ID: <20190913113355.GA32453@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20190912131143.u3rncvqdgx4z3ckz@willie-the-truck>
On Thu, Sep 12, 2019 at 02:11:44PM +0100, Will Deacon wrote:
> On Wed, Sep 11, 2019 at 04:15:46PM +0100, Mark Rutland wrote:
> > On Tue, Sep 10, 2019 at 03:40:44PM -0700, Sami Tolvanen wrote:
> > > Define a weak function in COND_SYSCALL instead of a weak alias to
> > > sys_ni_syscall, which has an incompatible type. This fixes indirect
> > > call mismatches with Control-Flow Integrity (CFI) checking.
> > >
> > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> >
> > This looks correct to me, builds fine, and I asume has been tested, so FWIW:
> >
> > Acked-by: Mark Rutland <mark.rutland@arm.com>
> >
> > In looking at this, I came to the conclusion that we can drop the ifdeffery
> > around our SYSCALL_DEFINE0(), COND_SYSCALL(), and SYS_NI(), which I evidently
> > cargo-culted from x86 (where the ifdeffery is actually necessary).
>
> Curious: why is it required on x86?
Due to the way they share some native calls with (IA32) compat, but need
slightly different wrappers to marshall registers, they have ifdeffery
like:
#ifdef CONFIG_IA32_EMULATION
#define COND_SYSCALL(name) \
cond_syscall(__x64_sys_##name); \
cond_syscall(__ia32_sys_##name)
#endif
#ifndef COND_SYSCALL
#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name)
#endif
... so that they define the compat wrapper when necessary, but not otherwise.
As we don't share the native syscall table with compat tasks, we don't
need to do anything like that, and can unconditionally define the native
case once.
> > I can send a follow up for that.
>
> Yes, please.
I'll cook that up now, atop of Sami's patch applied to arm64's
for-next/core.
Thanks,
Mark.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
prev parent reply other threads:[~2019-09-13 11:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-10 22:40 [PATCH] arm64: fix function types in COND_SYSCALL Sami Tolvanen
2019-09-11 15:15 ` Mark Rutland
2019-09-12 13:11 ` Will Deacon
2019-09-13 11:33 ` Mark Rutland [this message]
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=20190913113355.GA32453@lakrids.cambridge.arm.com \
--to=mark.rutland@arm.com \
--cc=catalin.marinas@arm.com \
--cc=keescook@chromium.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=samitolvanen@google.com \
--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).