From: Vladimir Murzin <vladimir.murzin@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: keescook@chromium.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] arm64: Support execute-only permissions with Enhanced PAN
Date: Tue, 8 Dec 2020 11:41:44 +0000 [thread overview]
Message-ID: <6de8d380-be38-f6c3-a05f-7daf908eb6de@arm.com> (raw)
In-Reply-To: <20201202182303.GC21091@gaia>
On 12/2/20 6:23 PM, Catalin Marinas wrote:
> On Thu, Nov 19, 2020 at 01:39:52PM +0000, Vladimir Murzin wrote:
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index 174817b..19147b6 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -579,6 +579,7 @@
>> #endif
>>
>> /* SCTLR_EL1 specific flags. */
>> +#define SCTLR_EL1_EPAN (BIT(57))
>> #define SCTLR_EL1_ATA0 (BIT(42))
>>
>> #define SCTLR_EL1_TCF0_SHIFT 38
>> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
>> index dcc165b..540245c 100644
>> --- a/arch/arm64/kernel/cpufeature.c
>> +++ b/arch/arm64/kernel/cpufeature.c
>> @@ -1602,6 +1602,14 @@ static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused)
>> }
>> #endif /* CONFIG_ARM64_PAN */
>>
>> +#ifdef CONFIG_ARM64_EPAN
>> +static void cpu_enable_epan(const struct arm64_cpu_capabilities *__unused)
>> +{
>> + sysreg_clear_set(sctlr_el1, 0, SCTLR_EL1_EPAN);
>> + local_flush_tlb_all();
>> +}
>> +#endif /* CONFIG_ARM64_EPAN */
>
> Thinking about this, can we not set the SCTLR_EL1.EPAN bit in proc.S
> directly, regardless of whether the system supports it or not (it should
> be write-ignored)? It would go in INIT_SCTLR_EL1_MMU_ON. We use the
> cpufeature entry only for detection, not enabling.
>
I'll try to restructure that way.
Cheers
Vladimir
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next prev parent reply other threads:[~2020-12-08 11:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 13:39 [PATCH 0/2] arm64: Support Enhanced PAN Vladimir Murzin
2020-11-19 13:39 ` [PATCH 1/2] arm64: Support execute-only permissions with " Vladimir Murzin
2020-11-19 18:22 ` Catalin Marinas
2020-11-19 18:52 ` Dave Martin
2020-11-27 18:31 ` Catalin Marinas
2020-12-02 18:23 ` Catalin Marinas
2020-12-08 11:41 ` Vladimir Murzin [this message]
2020-11-19 13:39 ` [PATCH 2/2] arm64: Introduce HWCAPS2_EXECONLY Vladimir Murzin
2020-12-08 16:36 ` Dave Martin
2020-12-08 17:34 ` Catalin Marinas
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