From: Will Deacon <will@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: bti: Fix support for userspace only BTI
Date: Tue, 12 May 2020 11:39:09 +0100 [thread overview]
Message-ID: <20200512103908.GB3021@willie-the-truck> (raw)
In-Reply-To: <20200512092155.56931-1-broonie@kernel.org>
On Tue, May 12, 2020 at 10:21:55AM +0100, Mark Brown wrote:
> When setting PTE_MAYBE_GP we check system_supports_bti() but this is
> true for systems where only CONFIG_BTI is set causing us to enable BTI
> on some kernel text. Add an extra check for the kernel mode option,
> using an ifdef due to line length.
>
> Fixes: c8027285e366 (arm64: Set GP bit in kernel page tables to enable BTI for the kernel)
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> arch/arm64/include/asm/pgtable-prot.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
> index 310690332896..3f07a044bdfb 100644
> --- a/arch/arm64/include/asm/pgtable-prot.h
> +++ b/arch/arm64/include/asm/pgtable-prot.h
> @@ -32,7 +32,11 @@ extern bool arm64_use_ng_mappings;
> #define PTE_MAYBE_NG (arm64_use_ng_mappings ? PTE_NG : 0)
> #define PMD_MAYBE_NG (arm64_use_ng_mappings ? PMD_SECT_NG : 0)
>
Might be worth a comment here in case somebody tries to "clean this up"
later on!
> +#ifdef CONFIG_ARM64_BTI_KERNEL
> #define PTE_MAYBE_GP (system_supports_bti() ? PTE_GP : 0)
> +#else
> +#define PTE_MAYBE_GP 0
> +#endif
I also notice we have a funny check in the vdso code:
if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti())
but why do we care about CONFIG_ARM64_BTI_KERNEL for the vdso pages?
Will
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next prev parent reply other threads:[~2020-05-12 10:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 9:21 [PATCH] arm64: bti: Fix support for userspace only BTI Mark Brown
2020-05-12 10:39 ` Will Deacon [this message]
2020-05-12 11:05 ` Mark Brown
2020-05-12 11:42 ` Will Deacon
2020-05-13 14:46 ` Dave Martin
2020-05-13 15:08 ` Mark Brown
2020-05-13 16:49 ` Dave Martin
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