From: Amit Kachhap <amit.kachhap@arm.com>
To: Suzuki Kuruppassery Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Kees Cook <keescook@chromium.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Henderson <richard.henderson@linaro.org>,
Kristina Martsenko <kristina.martsenko@arm.com>,
James Morse <james.morse@arm.com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
Mark Brown <Mark.Brown@arm.com>,
Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
Will Deacon <will@kernel.org>, Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v3 06/16] arm64: enable ptrauth earlier
Date: Thu, 9 Jan 2020 13:59:06 +0530 [thread overview]
Message-ID: <0c93c40c-e691-d768-da25-7f191624e56c@arm.com> (raw)
In-Reply-To: <e49002f2-53fb-b997-8bd6-363e22153da3@arm.com>
Hi Suzuki,
On 1/7/20 5:05 PM, Suzuki Kuruppassery Poulose wrote:
> On 16/12/2019 08:47, Amit Daniel Kachhap wrote:
>> From: Kristina Martsenko <kristina.martsenko@arm.com>
>>
>> When the kernel is compiled with pointer auth instructions, the boot CPU
>> needs to start using address auth very early, so change the cpucap to
>> account for this.
>>
>> Pointer auth must be enabled before we call C functions, because it is
>> not possible to enter a function with pointer auth disabled and exit it
>> with pointer auth enabled. Note, mismatches between architected and
>> IMPDEF algorithms will still be caught by the cpufeature framework (the
>> separate *_ARCH and *_IMP_DEF cpucaps).
>>
>> Note the change in behavior: if the boot CPU has address auth and a late
>> CPU does not, then we park the late CPU very early in booting. Also, if
>> the boot CPU does not have address auth and the late CPU has then system
>> panic will occur little later from inside the C code. Until now we would
>> have just disabled address auth in this case.
>>
>> Leave generic authentication as a "system scope" cpucap for now, since
>> initially the kernel will only use address authentication.
>>
>> Reviewed-by: Kees Cook <keescook@chromium.org>
>> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
>> [Amit: Re-worked ptrauth setup logic, comments]
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> ---
>> Changes since last version:
>> * None.
>>
>> arch/arm64/Kconfig | 5 +++++
>> arch/arm64/include/asm/smp.h | 1 +
>> arch/arm64/kernel/cpufeature.c | 13 +++----------
>> arch/arm64/kernel/head.S | 20 ++++++++++++++++++++
>> arch/arm64/kernel/smp.c | 2 ++
>> arch/arm64/mm/proc.S | 31 +++++++++++++++++++++++++++++++
>> 6 files changed, 62 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index b1b4476..5aabe8a 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -1482,6 +1482,11 @@ config ARM64_PTR_AUTH
>> be enabled. However, KVM guest also require VHE mode and hence
>> CONFIG_ARM64_VHE=y option to use this feature.
>> + If the feature is present on the primary CPU but not a
>> secondary CPU,
>> + then the secondary CPU will be parked.
>
> ---
>
>> Also, if the boot CPU does not
>> + have address auth and the late CPU has then system panic will
>> occur.
>> + On such a system, this option should not be selected.
>
> Is this part of the text true ? We do not enable ptr-auth on the CPUs if
> we are missing the support on primary. So, given we disable SCTLR bits,
> the ptr-auth instructions should be a NOP and is thus safe.
I got little confused with your earlier comments [1] and made the
secondary cpu's panic in case they have ptrauth and primary don't. In
this case ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU will leave it running and
not panic as you mentioned.
I will append ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU feature and update the
comments over here accordingly in my next iteration.
[1]: https://patchwork.kernel.org/patch/11195087/
>
> The rest looks good to me. With the above text removed,
>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Thanks for reviewing.
>
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next prev parent reply other threads:[~2020-01-09 8:30 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 8:47 [PATCH v3 00/16] arm64: return address signing Amit Daniel Kachhap
2019-12-16 8:47 ` [PATCH v3 01/16] arm64: cpufeature: add pointer auth meta-capabilities Amit Daniel Kachhap
2020-01-15 12:26 ` Catalin Marinas
2020-01-15 13:52 ` Suzuki Kuruppassery Poulose
2020-01-15 16:01 ` Catalin Marinas
2020-01-16 12:35 ` Amit Kachhap
2019-12-16 8:47 ` [PATCH v3 02/16] arm64: rename ptrauth key structures to be user-specific Amit Daniel Kachhap
2020-01-15 16:42 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 03/16] arm64: install user ptrauth keys at kernel exit time Amit Daniel Kachhap
2020-01-15 17:02 ` Catalin Marinas
2020-01-16 12:39 ` Amit Kachhap
2019-12-16 8:47 ` [PATCH v3 04/16] arm64: create macro to park cpu in an infinite loop Amit Daniel Kachhap
2020-01-07 11:13 ` Suzuki Kuruppassery Poulose
2020-01-15 17:03 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 05/16] arm64: ptrauth: Add bootup/runtime flags for __cpu_setup Amit Daniel Kachhap
2020-01-07 11:18 ` Suzuki Kuruppassery Poulose
2020-01-09 8:33 ` Amit Kachhap
2020-01-15 17:30 ` Catalin Marinas
2020-01-16 12:40 ` Amit Kachhap
2019-12-16 8:47 ` [PATCH v3 06/16] arm64: enable ptrauth earlier Amit Daniel Kachhap
2020-01-07 11:35 ` Suzuki Kuruppassery Poulose
2020-01-09 8:29 ` Amit Kachhap [this message]
2020-01-10 10:18 ` Suzuki Kuruppassery Poulose
2020-01-16 16:24 ` Catalin Marinas
2020-01-17 10:43 ` Amit Kachhap
2020-01-17 12:00 ` Catalin Marinas
2020-01-20 14:27 ` Amit Kachhap
2019-12-16 8:47 ` [PATCH v3 07/16] arm64: initialize and switch ptrauth kernel keys Amit Daniel Kachhap
2020-01-16 18:00 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 08/16] arm64: initialize ptrauth keys for kernel booting task Amit Daniel Kachhap
2020-01-16 17:59 ` Catalin Marinas
2020-01-20 10:50 ` Amit Kachhap
2019-12-16 8:47 ` [PATCH v3 09/16] arm64: mask PAC bits of __builtin_return_address Amit Daniel Kachhap
2020-01-17 10:14 ` Catalin Marinas
2020-01-20 14:20 ` Amit Kachhap
2020-01-21 16:52 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 10/16] arm64: unwind: strip PAC from kernel addresses Amit Daniel Kachhap
2020-01-17 10:22 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 11/16] arm64: __show_regs: strip PAC from lr in printk Amit Daniel Kachhap
2020-01-17 10:25 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 12/16] arm64: suspend: restore the kernel ptrauth keys Amit Daniel Kachhap
2020-01-17 10:31 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 13/16] arm64: kprobe: disable probe of ptrauth instruction Amit Daniel Kachhap
2020-01-17 11:16 ` Catalin Marinas
2020-01-20 14:24 ` Amit Kachhap
2019-12-16 8:47 ` [PATCH v3 14/16] kconfig: Add support for 'as-option' Amit Daniel Kachhap
2019-12-17 11:43 ` Masahiro Yamada
2020-01-17 11:33 ` Catalin Marinas
2020-01-17 17:51 ` Masahiro Yamada
2020-01-20 10:26 ` Vincenzo Frascino
2019-12-16 8:47 ` [PATCH v3 15/16] arm64: compile the kernel with ptrauth return address signing Amit Daniel Kachhap
2020-01-17 11:49 ` Catalin Marinas
2020-01-21 14:37 ` Amit Kachhap
2020-01-21 14:46 ` Vincenzo Frascino
2020-01-21 16:50 ` Catalin Marinas
2019-12-16 8:47 ` [PATCH v3 16/16] lkdtm: arm64: test kernel pointer authentication Amit Daniel Kachhap
2020-01-17 11:53 ` Catalin Marinas
2019-12-16 9:35 ` [RESEND PATCH v3 00/16] arm64: return address signing Amit Daniel Kachhap
2019-12-30 19:09 ` [PATCH " Kees Cook
2020-01-07 11:07 ` Amit Kachhap
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