From: Dave Martin <Dave.Martin@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
Andrey Konovalov <andreyknvl@google.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-kselftest@vger.kernel.org,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt
Date: Thu, 13 Jun 2019 14:23:43 +0100 [thread overview]
Message-ID: <20190613132342.GZ28398@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20190613122821.GS28951@C02TF0J2HF1T.local>
On Thu, Jun 13, 2019 at 01:28:21PM +0100, Catalin Marinas wrote:
> On Thu, Jun 13, 2019 at 12:37:32PM +0100, Dave P Martin wrote:
> > On Thu, Jun 13, 2019 at 11:15:34AM +0100, Vincenzo Frascino wrote:
> > > On 12/06/2019 16:35, Catalin Marinas wrote:
> > > > On Wed, Jun 12, 2019 at 03:21:10PM +0100, Vincenzo Frascino wrote:
> > > >> + - PR_GET_TAGGED_ADDR_CTRL: can be used to check the status of the Tagged
> > > >> + Address ABI.
> [...]
> > Is there a canonical way to detect whether this whole API/ABI is
> > available? (i.e., try to call this prctl / check for an HWCAP bit,
> > etc.)
>
> The canonical way is a prctl() call. HWCAP doesn't make sense since it's
> not a hardware feature. If you really want a different way of detecting
> this (which I don't think it's worth), we can reinstate the AT_FLAGS
> bit.
Sure, I think this probably makes sense -- I'm still getting my around
which parts of the design are directly related to MTE and which aren't.
I was a bit concerned about the interaction between
PR_SET_TAGGED_ADDR_CTRL and the sysctl: the caller might conclude that
this API is unavailable when actually tagged addresses are stuck on.
I'm not sure whether this matters, but it's a bit weird.
One option would be to change the semantics, so that the sysctl just
forbids turning tagging from off to on. Alternatively, we could return
a different error code to distinguish this case.
Or we just leave it as proposed.
Cheers
---Dave
next prev parent reply other threads:[~2019-06-13 13:23 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1560339705.git.andreyknvl@google.com>
2019-06-12 14:21 ` [PATCH v4 0/2] arm64 relaxed ABI Vincenzo Frascino
2019-06-12 14:21 ` Vincenzo Frascino
2019-06-12 14:21 ` [PATCH v4 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Vincenzo Frascino
2019-06-12 14:21 ` Vincenzo Frascino
2019-06-12 15:35 ` Catalin Marinas
2019-06-12 15:35 ` Catalin Marinas
2019-06-13 10:15 ` Vincenzo Frascino
2019-06-13 10:15 ` Vincenzo Frascino
2019-06-13 11:37 ` Dave Martin
2019-06-13 11:37 ` Dave Martin
2019-06-13 12:28 ` Catalin Marinas
2019-06-13 12:28 ` Catalin Marinas
2019-06-13 13:23 ` Dave Martin [this message]
2019-06-13 13:23 ` Dave Martin
2019-06-13 15:39 ` Catalin Marinas
2019-06-13 15:39 ` Catalin Marinas
2019-06-12 16:30 ` Szabolcs Nagy
2019-06-12 16:30 ` Szabolcs Nagy
2019-06-13 9:20 ` Catalin Marinas
2019-06-13 9:20 ` Catalin Marinas
2019-06-13 10:14 ` Szabolcs Nagy
2019-06-13 10:14 ` Szabolcs Nagy
2019-06-13 11:16 ` Vincenzo Frascino
2019-06-13 11:16 ` Vincenzo Frascino
2019-06-13 12:28 ` Szabolcs Nagy
2019-06-13 12:28 ` Szabolcs Nagy
2019-06-13 14:03 ` Vincenzo Frascino
2019-06-13 14:03 ` Vincenzo Frascino
2019-06-13 15:32 ` Szabolcs Nagy
2019-06-13 15:32 ` Szabolcs Nagy
2019-06-13 15:35 ` Vincenzo Frascino
2019-06-13 15:35 ` Vincenzo Frascino
2019-06-12 14:21 ` [PATCH v4 2/2] arm64: Relax Documentation/arm64/tagged-pointers.txt Vincenzo Frascino
2019-06-12 14:21 ` Vincenzo Frascino
2019-06-12 15:56 ` Catalin Marinas
2019-06-12 15:56 ` Catalin Marinas
2019-06-12 16:37 ` Szabolcs Nagy
2019-06-12 16:37 ` Szabolcs Nagy
2019-06-13 15:51 ` [PATCH v5 0/2] arm64 relaxed ABI Vincenzo Frascino
2019-06-13 15:51 ` Vincenzo Frascino
2019-06-13 15:51 ` [PATCH v5 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Vincenzo Frascino
2019-06-13 15:51 ` Vincenzo Frascino
2019-06-18 11:02 ` Szabolcs Nagy
2019-06-18 11:02 ` Szabolcs Nagy
2019-06-18 13:13 ` Kevin Brodsky
2019-06-18 13:13 ` Kevin Brodsky
2019-06-21 15:16 ` Catalin Marinas
2019-06-21 15:16 ` Catalin Marinas
2019-06-13 15:51 ` [PATCH v5 2/2] arm64: Relax Documentation/arm64/tagged-pointers.txt Vincenzo Frascino
2019-06-13 15:51 ` Vincenzo Frascino
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