From: Kristina Martsenko <kristina.martsenko@arm.com>
To: James Morse <james.morse@arm.com>,
Amit Daniel Kachhap <amit.kachhap@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: Wed, 13 Feb 2019 17:32:37 +0000 [thread overview]
Message-ID: <adbeb25c-fa88-41fd-7819-5f412a762b64@arm.com> (raw)
In-Reply-To: <88ccd568-f027-6cdf-b4f1-6709d76102c1@arm.com>
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.
>
> ('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:[~2019-02-13 17:32 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 [this message]
2019-02-14 10:53 ` Amit Daniel Kachhap
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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