From: Amit Daniel Kachhap <amit.kachhap@arm.com>
To: Kristina Martsenko <kristina.martsenko@arm.com>,
James Morse <james.morse@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
Marc Zyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
kvmarm@lists.cs.columbia.edu,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
Dave Martin <Dave.Martin@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/5] arm64: Add utilities to save restore pointer authentication keys
Date: Thu, 14 Feb 2019 16:23:53 +0530 [thread overview]
Message-ID: <41ab78a2-b2c0-61e9-e582-f2174d4203b5@arm.com> (raw)
In-Reply-To: <adbeb25c-fa88-41fd-7819-5f412a762b64@arm.com>
Hi,
On 2/13/19 11:02 PM, Kristina Martsenko wrote:
> On 31/01/2019 16:20, James Morse wrote:
>> Hi Amit,
>>
>> On 28/01/2019 06:58, Amit Daniel Kachhap wrote:
>>> The keys can be switched either inside an assembly or such
>>> functions which do not have pointer authentication checks, so a GCC
>>> attribute is added to enable it.
>>>
>>> A function ptrauth_keys_store is added which is similar to existing
>>> function ptrauth_keys_switch but saves the key values in memory.
>>> This may be useful for save/restore scenarios when CPU changes
>>> privilege levels, suspend/resume etc.
>>
>>
>>> diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
>>> index 15d4951..98441ce 100644
>>> --- a/arch/arm64/include/asm/pointer_auth.h
>>> +++ b/arch/arm64/include/asm/pointer_auth.h
>>> @@ -11,6 +11,13 @@
>>>
>>> #ifdef CONFIG_ARM64_PTR_AUTH
>>> /*
>>> + * Compile the function without pointer authentication instructions. This
>>> + * allows pointer authentication to be enabled/disabled within the function
>>> + * (but leaves the function unprotected by pointer authentication).
>>> + */
>>> +#define __no_ptrauth __attribute__((target("sign-return-address=none")))
>>
>> The documentation[0] for this says 'none' is the default. Will this only
>> take-effect once the kernel supports pointer-auth for the host? (Is this just
>> documentation until then?)
>
> Yes, I don't think this should be in this series, since we're not
> building the kernel with pointer auth yet.
I added it to stress on some functions which should be pointer
authentication safe. Yes this can be dropped and a small comment may
also do.
//Amit D
>
>>
>> ('noptrauth' would fit with 'notrace' slightly better)
>
> (But worse with e.g. __noreturn, __notrace_funcgraph, __init,
> __always_inline, __exception. Not sure what the pattern is. Would
> __noptrauth be better?)
>
> Thanks,
> Kristina
>
>>
>> [0]
>> https://gcc.gnu.org/onlinedocs/gcc/AArch64-Function-Attributes.html#AArch64-Function-Attributes
>>
>
next prev parent reply other threads:[~2019-02-14 10:54 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-28 6:58 [PATCH v5 0/6] Add ARMv8.3 pointer authentication for kvm guest Amit Daniel Kachhap
2019-01-28 6:58 ` [PATCH v5 1/5] arm64: Add utilities to save restore pointer authentication keys Amit Daniel Kachhap
2019-01-31 16:20 ` James Morse
2019-02-13 17:32 ` Kristina Martsenko
2019-02-14 10:53 ` Amit Daniel Kachhap [this message]
2019-01-28 6:58 ` [PATCH v5 2/5] arm64/kvm: preserve host HCR_EL2/MDCR_EL2 value Amit Daniel Kachhap
2019-01-31 16:22 ` James Morse
2019-02-14 9:49 ` Amit Daniel Kachhap
2019-02-13 17:34 ` Kristina Martsenko
2019-02-14 11:03 ` Amit Daniel Kachhap
2019-02-15 15:50 ` Kristina Martsenko
2019-01-28 6:58 ` [PATCH v5 3/5] arm64/kvm: context-switch ptrauth registers Amit Daniel Kachhap
2019-01-28 14:25 ` Julien Thierry
2019-01-31 16:25 ` [PATCH v5 3/5] arm64/kvm: context-switch ptrauth register James Morse
2019-02-13 17:35 ` Kristina Martsenko
2019-02-15 4:00 ` Amit Daniel Kachhap
2019-02-14 10:16 ` Amit Daniel Kachhap
2019-02-13 17:34 ` [PATCH v5 3/5] arm64/kvm: context-switch ptrauth registers Kristina Martsenko
2019-02-14 11:06 ` Amit Daniel Kachhap
2019-01-28 6:58 ` [PATCH v5 4/5] arm64/kvm: add a userspace option to enable pointer authentication Amit Daniel Kachhap
2019-01-28 14:35 ` Julien Thierry
2019-01-31 16:27 ` James Morse
2019-02-14 10:47 ` Amit Daniel Kachhap
2019-02-13 17:35 ` Kristina Martsenko
2019-02-15 4:49 ` Amit Daniel Kachhap
2019-01-28 6:58 ` [PATCH v5 5/5] arm64/kvm: control accessibility of ptrauth key registers Amit Daniel Kachhap
2019-02-13 17:35 ` Kristina Martsenko
2019-02-13 17:54 ` Dave P Martin
2019-02-15 4:57 ` Amit Daniel Kachhap
2019-01-28 6:58 ` [kvmtool PATCH v5 6/6] arm/kvm: arm64: Add a vcpu feature for pointer authentication Amit Daniel Kachhap
2019-01-28 14:56 ` Julien Thierry
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