From 8fbcc3343fff1404b8a5d11d2516e94965ca7be1 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Tue, 20 Mar 2018 20:20:49 +0000
Subject: [PATCH] Move the CR0.WP manipulation KPI to x86.

This should allow to avoid some #ifdefs in the common x86/ code.

Requested by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
---
 sys/amd64/amd64/machdep.c  | 25 -------------------------
 sys/amd64/include/md_var.h |  2 --
 sys/x86/include/x86_var.h  |  2 ++
 sys/x86/x86/cpu_machdep.c  | 26 ++++++++++++++++++++++++++
 4 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index fcc45eca57d..e340c6cd14d 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -2597,31 +2597,6 @@ clear_pcb_flags(struct pcb *pcb, const u_int flags)
 	    : "cc", "memory");
 }
 
-/*
- * Enable and restore kernel text write permissions.
- * Callers must ensure that disable_wp()/restore_wp() are executed
- * without rescheduling on the same core.
- */
-bool
-disable_wp(void)
-{
-	u_int cr0;
-
-	cr0 = rcr0();
-	if ((cr0 & CR0_WP) == 0)
-		return (false);
-	load_cr0(cr0 & ~CR0_WP);
-	return (true);
-}
-
-void
-restore_wp(bool old_wp)
-{
-
-	if (old_wp)
-		load_cr0(rcr0() | CR0_WP);
-}
-
 #ifdef KDB
 
 /*
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index abcc273b6c6..63dabaf4047 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -53,8 +53,6 @@ void	amd64_conf_fast_syscall(void);
 void	amd64_db_resume_dbreg(void);
 void	amd64_lower_shared_page(struct sysentvec *);
 void	amd64_syscall(struct thread *td, int traced);
-bool	disable_wp(void);
-void	restore_wp(bool old_wp);
 void	doreti_iret(void) __asm(__STRING(doreti_iret));
 void	doreti_iret_fault(void) __asm(__STRING(doreti_iret_fault));
 void	ld_ds(void) __asm(__STRING(ld_ds));
diff --git a/sys/x86/include/x86_var.h b/sys/x86/include/x86_var.h
index 46aa1afdfe3..6399e0154e7 100644
--- a/sys/x86/include/x86_var.h
+++ b/sys/x86/include/x86_var.h
@@ -119,6 +119,8 @@ void	busdma_swi(void);
 bool	cpu_mwait_usable(void);
 void	cpu_probe_amdc1e(void);
 void	cpu_setregs(void);
+bool	disable_wp(void);
+void	restore_wp(bool old_wp);
 void	dump_add_page(vm_paddr_t);
 void	dump_drop_page(vm_paddr_t);
 void	finishidentcpu(void);
diff --git a/sys/x86/x86/cpu_machdep.c b/sys/x86/x86/cpu_machdep.c
index 16f3b806436..ca35e00291e 100644
--- a/sys/x86/x86/cpu_machdep.c
+++ b/sys/x86/x86/cpu_machdep.c
@@ -621,3 +621,29 @@ hw_ibrs_disable_handler(SYSCTL_HANDLER_ARGS)
 SYSCTL_PROC(_hw, OID_AUTO, ibrs_disable, CTLTYPE_INT | CTLFLAG_RWTUN |
     CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0, hw_ibrs_disable_handler, "I",
     "Disable Indirect Branch Restricted Speculation");
+
+/*
+ * Enable and restore kernel text write permissions.
+ * Callers must ensure that disable_wp()/restore_wp() are executed
+ * without rescheduling on the same core.
+ */
+bool
+disable_wp(void)
+{
+	u_int cr0;
+
+	cr0 = rcr0();
+	if ((cr0 & CR0_WP) == 0)
+		return (false);
+	load_cr0(cr0 & ~CR0_WP);
+	return (true);
+}
+
+void
+restore_wp(bool old_wp)
+{
+
+	if (old_wp)
+		load_cr0(rcr0() | CR0_WP);
+}
+