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From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/5] arm64: bti: Support building kernel C code using BTI
Date: Fri, 27 Mar 2020 19:21:03 +0000	[thread overview]
Message-ID: <20200327192107.18394-2-broonie@kernel.org> (raw)
In-Reply-To: <20200327192107.18394-1-broonie@kernel.org>

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 f15f92ba53e6..12f942531f32 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -67,7 +67,11 @@ endif
 
 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
 # -march=armv8.3-a enables the non-nops instructions for PAC, to avoid the
 # compiler to generate them and consequently to break the single image contract
 # we pass it only to the assembler. This option is utilized only in case of non
-- 
2.20.1


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  reply	other threads:[~2020-03-27 19:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-27 19:21 [PATCH 0/5] arm64: Initial BTI kernel support Mark Brown
2020-03-27 19:21 ` Mark Brown [this message]
2020-03-28 21:14   ` [PATCH 1/5] arm64: bti: Support building kernel C code using BTI Kees Cook
2020-03-30 11:33     ` Mark Brown
2020-03-30 18:06       ` Kees Cook
2020-03-31 15:21         ` Mark Brown
2020-03-27 19:21 ` [PATCH 2/5] arm64: asm: Override SYM_FUNC_START when building the kernel with BTI Mark Brown
2020-03-27 19:21 ` [PATCH 3/5] arm64: Set GP bit in kernel page tables to enable BTI for the kernel Mark Brown
2020-03-27 19:21 ` [PATCH 4/5] arm64: mm: Mark module text as guarded pages Mark Brown
2020-03-27 19:21 ` [PATCH 5/5] arm64: bti: Provide Kconfig for kernel mode BTI Mark Brown
2020-03-28 21:19   ` Kees Cook

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