linux-kernel - [PATCH 21/22] x86/nospec: Refactor UNTRAIN_RET[

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Message-ID: <316ee83d450de92924273f65580a7d23f7355f40.1692580085.git.jpoimboe@kernel.org>
Date:   Sun, 20 Aug 2023 18:19:18 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Babu Moger <babu.moger@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, David.Kaplan@....com,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Nikolay Borisov <nik.borisov@...e.com>,
        gregkh@...uxfoundation.org, Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 21/22] x86/nospec: Refactor UNTRAIN_RET[_*]

Factor out the UNTRAIN_RET[_*] common bits into a helper macro.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/include/asm/nospec-branch.h | 31 +++++++++-------------------
 1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 51e3f1a287d2..dcc78477a38d 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -288,35 +288,24 @@
  * As such, this must be placed after every *SWITCH_TO_KERNEL_CR3 at a point
  * where we have a stack but before any RET instruction.
  */
-.macro UNTRAIN_RET
+.macro __UNTRAIN_RET ibpb_feature, call_depth_insns
 #if defined(CONFIG_RETHUNK) || defined(CONFIG_CPU_IBPB_ENTRY)
 	VALIDATE_UNRET_END
 	ALTERNATIVE_3 "",						\
 		      CALL_UNTRAIN_RET, X86_FEATURE_UNRET,		\
-		      "call entry_ibpb", X86_FEATURE_ENTRY_IBPB,	\
-		     __stringify(RESET_CALL_DEPTH), X86_FEATURE_CALL_DEPTH
+		      "call entry_ibpb", \ibpb_feature,			\
+		     __stringify(\call_depth_insns), X86_FEATURE_CALL_DEPTH
 #endif
 .endm
 
-.macro UNTRAIN_RET_VM
-#if defined(CONFIG_RETHUNK) || defined(CONFIG_CPU_IBPB_ENTRY)
-	VALIDATE_UNRET_END
-	ALTERNATIVE_3 "",						\
-		      CALL_UNTRAIN_RET, X86_FEATURE_UNRET,		\
-		      "call entry_ibpb", X86_FEATURE_IBPB_ON_VMEXIT,	\
-		      __stringify(RESET_CALL_DEPTH), X86_FEATURE_CALL_DEPTH
-#endif
-.endm
+#define UNTRAIN_RET \
+	__UNTRAIN_RET X86_FEATURE_ENTRY_IBPB, __stringify(RESET_CALL_DEPTH)
 
-.macro UNTRAIN_RET_FROM_CALL
-#if defined(CONFIG_RETHUNK) || defined(CONFIG_CPU_IBPB_ENTRY)
-	VALIDATE_UNRET_END
-	ALTERNATIVE_3 "",						\
-		      CALL_UNTRAIN_RET, X86_FEATURE_UNRET,		\
-		      "call entry_ibpb", X86_FEATURE_ENTRY_IBPB,	\
-		      __stringify(RESET_CALL_DEPTH_FROM_CALL), X86_FEATURE_CALL_DEPTH
-#endif
-.endm
+#define UNTRAIN_RET_VM \
+	__UNTRAIN_RET X86_FEATURE_IBPB_ON_VMEXIT, __stringify(RESET_CALL_DEPTH)
+
+#define UNTRAIN_RET_FROM_CALL \
+	__UNTRAIN_RET X86_FEATURE_ENTRY_IBPB, __stringify(RESET_CALL_DEPTH_FROM_CALL)
 
 
 .macro CALL_DEPTH_ACCOUNT
-- 
2.41.0