From 7fbf47c7ce50b38a64576b150e7011ae73d54669 Mon Sep 17 00:00:00 2001
From: Alexandre Chartre <alexandre.chartre@oracle.com>
Date: Tue, 14 Jun 2022 23:15:50 +0200
Subject: x86/bugs: Add AMD retbleed= boot parameter

Add the "retbleed=<value>" boot parameter to select a mitigation for
RETBleed. Possible values are "off", "auto" and "unret"
(JMP2RET mitigation). The default value is "auto".

Currently, "retbleed=auto" will select the unret mitigation on
AMD and Hygon and no mitigation on Intel (JMP2RET is not effective on
Intel).

  [peterz: rebase; add hygon]
  [jpoimboe: cleanups]

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/Kconfig | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'arch/x86/Kconfig')

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index be0b95e51df6..e35eecfb74f2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -475,6 +475,9 @@ config RETPOLINE
 config CC_HAS_SLS
 	def_bool $(cc-option,-mharden-sls=all)
 
+config CC_HAS_RETURN_THUNK
+	def_bool $(cc-option,-mfunction-return=thunk-extern)
+
 config SLS
 	bool "Mitigate Straight-Line-Speculation"
 	depends on CC_HAS_SLS && X86_64
-- 
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