From: Mark Brown <broonie@kernel.org>
To: Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
Mark Brown <broonie@kernel.org>,
Amit Kachhap <amit.kachhap@arm.com>,
Dave Martin <Dave.Martin@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 03/11] arm64: asm: Override SYM_FUNC_START when building the kernel with BTI
Date: Wed, 6 May 2020 20:51:30 +0100 [thread overview]
Message-ID: <20200506195138.22086-4-broonie@kernel.org> (raw)
In-Reply-To: <20200506195138.22086-1-broonie@kernel.org>
When the kernel is built for BTI override SYM_FUNC_START and related macros
to add a BTI landing pad to the start of all global functions, ensuring that
they are BTI safe. The ; at the end of the BTI_x macros is for the
benefit of the macro-generated functions in xen-hypercall.S.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/linkage.h | 46 ++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
index ebee3113a62f..b5a7998a6b2a 100644
--- a/arch/arm64/include/asm/linkage.h
+++ b/arch/arm64/include/asm/linkage.h
@@ -4,6 +4,52 @@
#define __ALIGN .align 2
#define __ALIGN_STR ".align 2"
+#if defined(CONFIG_ARM64_BTI_KERNEL) && defined(__aarch64__)
+
+/*
+ * Since current versions of gas reject the BTI instruction unless we
+ * set the architecture version to v8.5 we use the hint instruction
+ * instead.
+ */
+#define BTI_C hint 34 ;
+#define BTI_J hint 36 ;
+
+/*
+ * When using in-kernel BTI we need to ensure that assembly functions
+ * have suitable annotations. Override SYM_FUNC_START to insert a BTI
+ * landing pad at the start of everything.
+ */
+#define SYM_FUNC_START(name) \
+ SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \
+ BTI_C
+
+#define SYM_FUNC_START_NOALIGN(name) \
+ SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE) \
+ BTI_C
+
+#define SYM_FUNC_START_LOCAL(name) \
+ SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN) \
+ BTI_C
+
+#define SYM_FUNC_START_LOCAL_NOALIGN(name) \
+ SYM_START(name, SYM_L_LOCAL, SYM_A_NONE) \
+ BTI_C
+
+#define SYM_FUNC_START_WEAK(name) \
+ SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN) \
+ BTI_C
+
+#define SYM_FUNC_START_WEAK_NOALIGN(name) \
+ SYM_START(name, SYM_L_WEAK, SYM_A_NONE) \
+ BTI_C
+
+#define SYM_INNER_LABEL(name, linkage) \
+ .type name SYM_T_NONE ASM_NL \
+ SYM_ENTRY(name, linkage, SYM_A_NONE) \
+ BTI_J
+
+#endif
+
/*
* Annotate a function as position independent, i.e., safe to be called before
* the kernel virtual mapping is activated.
--
2.20.1
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next prev parent reply other threads:[~2020-05-06 19:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-06 19:51 [PATCH v3 00/11] arm64: BTI kernel and vDSO support Mark Brown
2020-05-06 19:51 ` [PATCH v3 01/11] arm64: Document why we enable PAC support for leaf functions Mark Brown
2020-05-06 19:51 ` [PATCH v3 02/11] arm64: bti: Support building kernel C code using BTI Mark Brown
2020-05-06 19:51 ` Mark Brown [this message]
2020-05-06 19:51 ` [PATCH v3 04/11] arm64: Set GP bit in kernel page tables to enable BTI for the kernel Mark Brown
2020-05-06 19:51 ` [PATCH v3 05/11] arm64: bpf: Annotate JITed code for BTI Mark Brown
2020-05-07 20:15 ` Daniel Borkmann
2020-05-07 20:15 ` Daniel Borkmann
2020-05-06 19:51 ` [PATCH v3 06/11] arm64: mm: Mark executable text as guarded pages Mark Brown
2020-05-06 19:51 ` [PATCH v3 07/11] arm64: bti: Provide Kconfig for kernel mode BTI Mark Brown
2020-05-06 19:51 ` [PATCH v3 08/11] arm64: asm: Provide a mechanism for generating ELF note for BTI Mark Brown
2020-05-06 19:51 ` [PATCH v3 09/11] arm64: vdso: Annotate " Mark Brown
2020-05-06 19:51 ` [PATCH v3 10/11] arm64: vdso: Force the vDSO to be linked as BTI when built " Mark Brown
2020-05-06 19:51 ` [PATCH v3 11/11] arm64: vdso: Map the vDSO text with guarded pages " Mark Brown
2020-05-07 14:33 ` [PATCH v3 00/11] arm64: BTI kernel and vDSO support Will Deacon
2020-05-07 14:35 ` Will Deacon
2020-05-07 14:59 ` Will Deacon
2020-05-07 15:09 ` Mark Brown
2020-05-07 15:18 ` Will Deacon
2020-05-07 15:48 ` Mark Brown
2020-05-07 15:55 ` Will Deacon
2020-05-07 16:30 ` Mark Brown
2020-05-07 16:36 ` Will Deacon
2020-05-07 16:47 ` Mark Brown
2020-05-08 16:53 ` Mark Brown
2020-05-07 15:07 ` Mark Brown
2020-05-07 15:26 ` Will Deacon
2020-05-07 17:25 ` Will Deacon
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