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From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
	jpoimboe@redhat.com, andrew.cooper3@citrix.com
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	ndesaulniers@google.com, keescook@chromium.org,
	samitolvanen@google.com
Subject: [RFC][PATCH 2/6] x86: Base IBT bits
Date: Mon, 22 Nov 2021 18:03:03 +0100	[thread overview]
Message-ID: <20211122170805.088195171@infradead.org> (raw)
In-Reply-To: 20211122170301.764232470@infradead.org

Add Kconfig, Makefile and basic instruction support for x86 IBT.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/Kconfig           |   10 ++++++++++
 arch/x86/Makefile          |    5 ++++-
 arch/x86/include/asm/ibt.h |   40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1848,6 +1848,16 @@ config X86_UMIP
 	  specific cases in protected and virtual-8086 modes. Emulated
 	  results are dummy.
 
+config CC_HAS_IBT
+	def_bool $(cc-option, -fcf-protection=branch)
+
+config X86_IBT
+	prompt "Indirect Branch Tracking"
+	bool
+	depends on X86_64 && CC_HAS_IBT
+	help
+	  Increase kernel text size for giggles
+
 config X86_INTEL_MEMORY_PROTECTION_KEYS
 	prompt "Memory Protection Keys"
 	def_bool y
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -50,8 +50,11 @@ export BITS
 #
 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
 
-# Intel CET isn't enabled in the kernel
+ifeq ($(CONFIG_X86_IBT),y)
+KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch)
+else
 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
+endif
 
 ifeq ($(CONFIG_X86_32),y)
         BITS := 32
--- /dev/null
+++ b/arch/x86/include/asm/ibt.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_IBT_H
+#define _ASM_X86_IBT_H
+
+#ifdef CONFIG_X86_IBT
+
+#ifndef __ASSEMBLY__
+
+// XXX note about GAS version required
+
+#ifdef CONFIG_X86_64
+#define ASM_ENDBR	".byte 0xf3, 0x0f, 0x1e, 0xfa\n\t"
+#else
+#define ASM_ENDBR	".byte 0xf3, 0x0f, 0x1e, 0xfb\n\t"
+#endif
+
+#else /* __ASSEMBLY__ */
+
+#ifdef CONFIG_X86_64
+#define ENDBR	.byte 0xf3, 0x0f, 0x1e, 0xfa
+#else
+#define ENDBR	.byte 0xf3, 0x0f, 0x1e, 0xfb
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#else /* !IBT */
+
+#ifndef __ASSEMBLY__
+
+#define ASM_ENDBR
+
+#else /* __ASSEMBLY__ */
+
+#define ENDBR
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_X86_IBT */
+#endif /* _ASM_X86_IBT_H */



  parent reply	other threads:[~2021-11-22 17:14 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-22 17:03 [RFC][PATCH 0/6] x86: Kernel IBT beginnings Peter Zijlstra
2021-11-22 17:03 ` [RFC][PATCH 1/6] x86: Annotate _THIS_IP_ Peter Zijlstra
2021-11-23 13:53   ` Mark Rutland
2021-11-23 14:14     ` Peter Zijlstra
2021-11-24 18:18       ` Josh Poimboeuf
2021-11-22 17:03 ` Peter Zijlstra [this message]
2022-02-08 23:32   ` [RFC][PATCH 2/6] x86: Base IBT bits Kees Cook
2021-11-22 17:03 ` [RFC][PATCH 3/6] x86: Add ENDBR to IRET-to-Self Peter Zijlstra
2021-11-22 18:09   ` Peter Zijlstra
2022-02-08 23:33     ` Kees Cook
2021-11-22 17:03 ` [RFC][PATCH 4/6] objtool: Read the _THIS_IP_ hints Peter Zijlstra
2021-11-22 17:03 ` [RFC][PATCH 5/6] x86: Sprinkle ENDBR dust Peter Zijlstra
2021-11-23 14:00   ` Mark Rutland
2021-11-23 14:21     ` Peter Zijlstra
2022-02-08 23:38     ` Kees Cook
2021-11-22 17:03 ` [RFC][PATCH 6/6] objtool: Add IBT validation / fixups Peter Zijlstra
2021-11-24 19:30   ` Josh Poimboeuf
2022-02-08 23:43     ` Kees Cook
2022-02-09  5:09       ` Josh Poimboeuf
2022-02-09 11:41       ` Peter Zijlstra
2022-02-09 11:45         ` Peter Zijlstra
2021-12-24  2:05   ` joao
2022-02-08 23:42     ` Kees Cook
2022-02-09  2:21       ` Joao Moreira
2022-02-09  4:05         ` Kees Cook
2022-02-09  5:18           ` Joao Moreira
2022-02-11 13:38             ` Peter Zijlstra
2022-02-14 21:38               ` Sami Tolvanen
2022-02-14 22:25                 ` Peter Zijlstra
2022-02-15 16:56                   ` Sami Tolvanen
2022-02-15 20:03                     ` Kees Cook
2022-02-15 21:05                       ` Peter Zijlstra
2022-02-15 23:05                         ` Kees Cook
2022-02-15 23:38                           ` Joao Moreira
2022-02-16 12:24                         ` Peter Zijlstra
2022-02-15 20:53                     ` Peter Zijlstra
2022-02-15 22:45               ` Joao Moreira
2022-02-16  0:57               ` Andrew Cooper
2022-03-02  3:06               ` Peter Collingbourne
2022-03-02  3:32                 ` Joao Moreira
2022-06-08 17:53                 ` Fāng-ruì Sòng
2022-06-09  0:05                   ` Sami Tolvanen
2021-11-23  7:58 ` [RFC][PATCH 0/6] x86: Kernel IBT beginnings Christoph Hellwig
2021-11-23  9:02   ` Peter Zijlstra
2022-02-08 23:48 ` Kees Cook
2022-02-09  0:09 ` Nick Desaulniers

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