x86/bugs: Rename entry_ibpb() to write_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@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/1e54ace131e79b760de3fe828264e26d0896e3ac.1744148254.git.jpoimboe@kernel.org

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
 

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);

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.
 				 */