From: Catalin Marinas <catalin.marinas@arm.com>
To: Vladimir Murzin <vladimir.murzin@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: Wed, 2 Dec 2020 18:23:03 +0000 [thread overview]
Message-ID: <20201202182303.GC21091@gaia> (raw)
In-Reply-To: <20201119133953.15585-2-vladimir.murzin@arm.com>
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.
--
Catalin
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next prev parent reply other threads:[~2020-12-02 18:24 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 [this message]
2020-12-08 11:41 ` Vladimir Murzin
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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