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From:   Yu-cheng Yu <yu-cheng.yu@intel.com>
To:     x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
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Cc:     Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v12 1/8] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking
Date:   Fri, 18 Sep 2020 12:23:05 -0700
Message-Id: <20200918192312.25978-2-yu-cheng.yu@intel.com>
In-Reply-To: <20200918192312.25978-1-yu-cheng.yu@intel.com>
References: <20200918192312.25978-1-yu-cheng.yu@intel.com>
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Introduce Kconfig option X86_INTEL_BRANCH_TRACKING_USER.

Indirect Branch Tracking (IBT) provides protection against CALL-/JMP-
oriented programming attacks.  It is active when the kernel has this
feature enabled, and the processor and the application support it.
When this feature is enabled, legacy non-IBT applications continue to
work, but without IBT protection.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
v10:
- Change build-time CET check to config depends on.

 arch/x86/Kconfig | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6b6dad011763..b047e0a8d1c2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1963,6 +1963,22 @@ config X86_INTEL_SHADOW_STACK_USER
 
 	  If unsure, say y.
 
+config X86_INTEL_BRANCH_TRACKING_USER
+	prompt "Intel Indirect Branch Tracking for user-mode"
+	def_bool n
+	depends on CPU_SUP_INTEL && X86_64
+	depends on $(cc-option,-fcf-protection)
+	select X86_INTEL_CET
+	help
+	  Indirect Branch Tracking (IBT) provides protection against
+	  CALL-/JMP-oriented programming attacks.  It is active when
+	  the kernel has this feature enabled, and the processor and
+	  the application support it.  When this feature is enabled,
+	  legacy non-IBT applications continue to work, but without
+	  IBT protection.
+
+	  If unsure, say y
+
 config EFI
 	bool "EFI runtime service support"
 	depends on ACPI
-- 
2.21.0