From: Dave Martin <Dave.Martin@arm•com>
To: Mark Brown <broonie@kernel•org>
Cc: Catalin Marinas <catalin.marinas@arm•com>,
Vincenzo Frascino <Vincenzo.Frascino@arm•com>,
Will Deacon <will@kernel•org>, Kees Cook <keescook@chromium•org>,
linux-arm-kernel@lists•infradead.org
Subject: Re: [PATCH v2 01/10] arm64: bti: Support building kernel C code using BTI
Date: Tue, 5 May 2020 17:50:45 +0100 [thread overview]
Message-ID: <20200505165045.GQ30377@arm.com> (raw)
In-Reply-To: <20200429211641.9279-2-broonie@kernel.org>
On Wed, Apr 29, 2020 at 10:16:32PM +0100, Mark Brown wrote:
> When running with BTI enabled we need to ask the compiler to enable
> generation of BTI landing pads beyond those generated as a result of
> pointer authentication instructions being landing pads. Since the two
> features are practically speaking unlikely to be used separately we
> will make kernel mode BTI depend on pointer authentication in order
> to simplify the Makefile.
>
> Signed-off-by: Mark Brown <broonie@kernel•org>
> ---
> arch/arm64/Makefile | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 85e4149cc5d5..90150b5b180e 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -71,7 +71,11 @@ branch-prot-flags-y += $(call cc-option,-mbranch-protection=none)
>
> ifeq ($(CONFIG_ARM64_PTR_AUTH),y)
> branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all
> +ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
> +branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI) := -mbranch-protection=pac-ret+leaf+bti
> +else
> branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf
> +endif
Is it worth a comment to explain how this differs from
-mbranch-protection=standard, and why we're not using that here?
Cheers
---Dave
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next prev parent reply other threads:[~2020-05-05 16:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 21:16 [PATCH v2 00/10] arm64: BTI kernel and vDSO support Mark Brown
2020-04-29 21:16 ` [PATCH v2 01/10] arm64: bti: Support building kernel C code using BTI Mark Brown
2020-05-05 16:50 ` Dave Martin [this message]
2020-05-05 17:31 ` Mark Brown
2020-05-06 12:24 ` Amit Kachhap
2020-04-29 21:16 ` [PATCH v2 02/10] arm64: asm: Override SYM_FUNC_START when building the kernel with BTI Mark Brown
2020-05-05 14:56 ` Will Deacon
2020-05-05 15:18 ` Mark Brown
2020-05-05 16:08 ` Will Deacon
2020-05-05 17:21 ` Mark Brown
2020-05-06 7:10 ` Will Deacon
2020-05-06 10:41 ` Mark Brown
2020-05-06 10:50 ` Will Deacon
2020-05-06 11:43 ` Mark Brown
2020-05-06 12:27 ` Will Deacon
2020-05-06 13:03 ` Mark Brown
2020-05-06 13:40 ` Dave Martin
2020-05-06 14:45 ` Will Deacon
2020-05-06 15:25 ` Mark Brown
2020-05-06 15:48 ` Will Deacon
2020-05-06 15:33 ` Dave Martin
2020-04-29 21:16 ` [PATCH v2 03/10] arm64: Set GP bit in kernel page tables to enable BTI for the kernel Mark Brown
2020-04-29 21:16 ` [PATCH v2 04/10] arm64: bpf: Annotate JITed code for BTI Mark Brown
2020-04-29 21:16 ` [PATCH v2 05/10] arm64: mm: Mark executable text as guarded pages Mark Brown
2020-04-29 21:16 ` [PATCH v2 06/10] arm64: bti: Provide Kconfig for kernel mode BTI Mark Brown
2020-04-29 21:16 ` [PATCH v2 07/10] arm64: asm: Provide a mechanism for generating ELF note for BTI Mark Brown
2020-05-05 14:58 ` Will Deacon
2020-05-05 16:51 ` Dave Martin
2020-05-05 17:06 ` Mark Brown
2020-05-06 11:26 ` Will Deacon
2020-05-06 12:38 ` Mark Brown
2020-05-06 13:44 ` Will Deacon
2020-05-06 15:39 ` Mark Brown
2020-04-29 21:16 ` [PATCH v2 08/10] arm64: vdso: Annotate " Mark Brown
2020-04-29 21:16 ` [PATCH v2 09/10] arm64: vdso: Force the vDSO to be linked as BTI when built " Mark Brown
2020-04-29 21:16 ` [PATCH v2 10/10] arm64: vdso: Map the vDSO text with guarded pages " Mark Brown
2020-04-30 17:18 ` [PATCH v2 00/10] arm64: BTI kernel and vDSO support Catalin Marinas
2020-04-30 17:23 ` Mark Brown
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