linux-kernel - [PATCH v3 1/6] x86/bugs: Rename entry

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Message-ID: <a3ce1558b68a64f52ea56000f2bbdfd6e7799258.1743617897.git.jpoimboe@kernel.org>
Date: Wed,  2 Apr 2025 11:19:18 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	amit@...nel.org,
	kvm@...r.kernel.org,
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Subject: [PATCH v3 1/6] x86/bugs: Rename entry_ibpb()

There's nothing entry-specific about entry_ibpb().  In preparation for
calling it from elsewhere, rename it to __write_ibpb().

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/entry/entry.S               | 7 ++++---
 arch/x86/include/asm/nospec-branch.h | 6 +++---
 arch/x86/kernel/cpu/bugs.c           | 6 +++---
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
index d3caa31240ed..3a53319988b9 100644
--- a/arch/x86/entry/entry.S
+++ b/arch/x86/entry/entry.S
@@ -17,7 +17,8 @@
 
 .pushsection .noinstr.text, "ax"
 
-SYM_FUNC_START(entry_ibpb)
+// Clobbers AX, CX, DX
+SYM_FUNC_START(__write_ibpb)
 	ANNOTATE_NOENDBR
 	movl	$MSR_IA32_PRED_CMD, %ecx
 	movl	$PRED_CMD_IBPB, %eax
@@ -27,9 +28,9 @@ SYM_FUNC_START(entry_ibpb)
 	/* Make sure IBPB clears return stack preductions too. */
 	FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET
 	RET
-SYM_FUNC_END(entry_ibpb)
+SYM_FUNC_END(__write_ibpb)
 /* For KVM */
-EXPORT_SYMBOL_GPL(entry_ibpb);
+EXPORT_SYMBOL_GPL(__write_ibpb);
 
 .popsection
 
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 8a5cc8e70439..bbac79cad04c 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -269,7 +269,7 @@
  * typically has NO_MELTDOWN).
  *
  * While retbleed_untrain_ret() doesn't clobber anything but requires stack,
- * entry_ibpb() will clobber AX, CX, DX.
+ * __write_ibpb() will clobber AX, CX, DX.
  *
  * 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.
@@ -279,7 +279,7 @@
 	VALIDATE_UNRET_END
 	CALL_UNTRAIN_RET
 	ALTERNATIVE_2 "",						\
-		      "call entry_ibpb", \ibpb_feature,			\
+		      "call __write_ibpb", \ibpb_feature,			\
 		     __stringify(\call_depth_insns), X86_FEATURE_CALL_DEPTH
 #endif
 .endm
@@ -368,7 +368,7 @@ extern void srso_return_thunk(void);
 extern void srso_alias_return_thunk(void);
 
 extern void entry_untrain_ret(void);
-extern void entry_ibpb(void);
+extern void __write_ibpb(void);
 
 #ifdef CONFIG_X86_64
 extern void clear_bhb_loop(void);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4386aa6c69e1..310cb3f7139c 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1142,7 +1142,7 @@ static void __init retbleed_select_mitigation(void)
 		setup_clear_cpu_cap(X86_FEATURE_RETHUNK);
 
 		/*
-		 * There is no need for RSB filling: entry_ibpb() ensures
+		 * There is no need for RSB filling: __write_ibpb() ensures
 		 * all predictions, including the RSB, are invalidated,
 		 * regardless of IBPB implementation.
 		 */
@@ -2676,7 +2676,7 @@ static void __init srso_select_mitigation(void)
 				setup_clear_cpu_cap(X86_FEATURE_RETHUNK);
 
 				/*
-				 * There is no need for RSB filling: entry_ibpb() ensures
+				 * There is no need for RSB filling: __write_ibpb() ensures
 				 * all predictions, including the RSB, are invalidated,
 				 * regardless of IBPB implementation.
 				 */
@@ -2701,7 +2701,7 @@ static void __init srso_select_mitigation(void)
 				srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
 
 				/*
-				 * There is no need for RSB filling: entry_ibpb() ensures
+				 * There is no need for RSB filling: __write_ibpb() ensures
 				 * all predictions, including the RSB, are invalidated,
 				 * regardless of IBPB implementation.
 				 */
-- 
2.48.1