From: Will Deacon <will@kernel.org>
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>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Will Deacon <will.deacon@arm.com>,
Dave Hansen <dave.hansen@intel.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 2/2] arm64: Relax Documentation/arm64/tagged-pointers.rst
Date: Thu, 8 Aug 2019 18:06:52 +0100 [thread overview]
Message-ID: <20190808170651.c6hflztfunjmisgm@willie-the-truck> (raw)
In-Reply-To: <20190807155321.9648-3-catalin.marinas@arm.com>
On Wed, Aug 07, 2019 at 04:53:21PM +0100, Catalin Marinas wrote:
> From: Vincenzo Frascino <vincenzo.frascino@arm.com>
>
> On arm64 the TCR_EL1.TBI0 bit has been always enabled hence
> the userspace (EL0) is allowed to set a non-zero value in the
> top byte but the resulting pointers are not allowed at the
> user-kernel syscall ABI boundary.
>
> With the relaxed ABI proposed in this set, it is now possible to pass
> tagged pointers to the syscalls, when these pointers are in memory
> ranges obtained by an anonymous (MAP_ANONYMOUS) mmap().
>
> Relax the requirements described in tagged-pointers.rst to be compliant
> with the behaviours guaranteed by the ARM64 Tagged Address ABI.
>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Andrey Konovalov <andreyknvl@google.com>
> Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
> Cc: Kevin Brodsky <kevin.brodsky@arm.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> [catalin.marinas@arm.com: minor tweaks]
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
> Documentation/arm64/tagged-pointers.rst | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/arm64/tagged-pointers.rst b/Documentation/arm64/tagged-pointers.rst
> index 2acdec3ebbeb..82a3eff71a70 100644
> --- a/Documentation/arm64/tagged-pointers.rst
> +++ b/Documentation/arm64/tagged-pointers.rst
> @@ -20,7 +20,8 @@ Passing tagged addresses to the kernel
> --------------------------------------
>
> All interpretation of userspace memory addresses by the kernel assumes
> -an address tag of 0x00.
> +an address tag of 0x00, unless the application enables the AArch64
> +Tagged Address ABI explicitly.
I think we should have the link to Documentation/arm64/tagged-address-abi.rst
here so people see it when it's first referenced.
> +The AArch64 Tagged Address ABI description and the guarantees it
> +provides can be found in: Documentation/arm64/tagged-address-abi.rst.
Then this sentence can be dropped.
Will
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next prev parent reply other threads:[~2019-08-08 17:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 15:53 [PATCH v7 0/2] arm64 tagged address ABI Catalin Marinas
2019-08-07 15:53 ` [PATCH v7 1/2] arm64: Define Documentation/arm64/tagged-address-abi.rst Catalin Marinas
2019-08-07 20:38 ` Dave Hansen
2019-08-08 9:25 ` Szabolcs Nagy
2019-08-08 16:20 ` Szabolcs Nagy
2019-08-08 16:27 ` Dave Martin
2019-08-08 17:27 ` Catalin Marinas
2019-08-09 14:10 ` Dave Hansen
2019-08-12 17:36 ` Catalin Marinas
2019-08-13 11:10 ` Dave Martin
2019-08-08 16:30 ` Szabolcs Nagy
2019-08-08 17:04 ` Will Deacon
2019-08-12 10:46 ` Andrew Murray
2019-08-12 17:17 ` Catalin Marinas
2019-08-07 15:53 ` [PATCH v7 2/2] arm64: Relax Documentation/arm64/tagged-pointers.rst Catalin Marinas
2019-08-08 17:06 ` Will Deacon [this message]
2019-08-08 9:32 ` [PATCH v7 0/2] arm64 tagged address ABI Szabolcs Nagy
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