--- zzzz-none-000/linux-3.10.107/arch/um/kernel/skas/mmu.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/um/kernel/skas/mmu.c	2021-02-04 17:41:59.000000000 +0000
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
@@ -8,12 +9,11 @@
 #include <linux/slab.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
+#include <asm/sections.h>
 #include <as-layout.h>
 #include <os.h>
 #include <skas.h>
 
-extern int __syscall_stub_start;
-
 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 			 unsigned long kernel)
 {
@@ -54,35 +54,24 @@
 	unsigned long stack = 0;
 	int ret = -ENOMEM;
 
-	if (skas_needs_stub) {
-		stack = get_zeroed_page(GFP_KERNEL);
-		if (stack == 0)
-			goto out;
-	}
+	stack = get_zeroed_page(GFP_KERNEL);
+	if (stack == 0)
+		goto out;
 
 	to_mm->id.stack = stack;
 	if (current->mm != NULL && current->mm != &init_mm)
 		from_mm = &current->mm->context;
 
-	if (proc_mm) {
-		ret = new_mm(stack);
-		if (ret < 0) {
-			printk(KERN_ERR "init_new_context_skas - "
-			       "new_mm failed, errno = %d\n", ret);
-			goto out_free;
-		}
-		to_mm->id.u.mm_fd = ret;
-	}
-	else {
-		if (from_mm)
-			to_mm->id.u.pid = copy_context_skas0(stack,
-							     from_mm->id.u.pid);
-		else to_mm->id.u.pid = start_userspace(stack);
-
-		if (to_mm->id.u.pid < 0) {
-			ret = to_mm->id.u.pid;
-			goto out_free;
-		}
+	block_signals();
+	if (from_mm)
+		to_mm->id.u.pid = copy_context_skas0(stack,
+						     from_mm->id.u.pid);
+	else to_mm->id.u.pid = start_userspace(stack);
+	unblock_signals();
+
+	if (to_mm->id.u.pid < 0) {
+		ret = to_mm->id.u.pid;
+		goto out_free;
 	}
 
 	ret = init_new_ldt(to_mm, from_mm);
@@ -105,11 +94,8 @@
 {
 	int err, ret;
 
-	if (!skas_needs_stub)
-		return;
-
 	ret = init_stub_pte(mm, STUB_CODE,
-			    (unsigned long) &__syscall_stub_start);
+			    (unsigned long) __syscall_stub_start);
 	if (ret)
 		goto out;
 
@@ -117,13 +103,13 @@
 	if (ret)
 		goto out;
 
-	mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start);
+	mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
 	mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
 
 	/* dup_mmap already holds mmap_sem */
 	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
 				      VM_READ | VM_MAYREAD | VM_EXEC |
-				      VM_MAYEXEC | VM_DONTCOPY,
+				      VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
 				      mm->context.stub_pages);
 	if (err) {
 		printk(KERN_ERR "install_special_mapping returned %d\n", err);
@@ -154,25 +140,19 @@
 {
 	struct mm_context *mmu = &mm->context;
 
-	if (proc_mm)
-		os_close_file(mmu->id.u.mm_fd);
-	else {
-		/*
-		 * If init_new_context wasn't called, this will be
-		 * zero, resulting in a kill(0), which will result in the
-		 * whole UML suddenly dying.  Also, cover negative and
-		 * 1 cases, since they shouldn't happen either.
-		 */
-		if (mmu->id.u.pid < 2) {
-			printk(KERN_ERR "corrupt mm_context - pid = %d\n",
-			       mmu->id.u.pid);
-			return;
-		}
-		os_kill_ptraced_process(mmu->id.u.pid, 1);
+	/*
+	 * If init_new_context wasn't called, this will be
+	 * zero, resulting in a kill(0), which will result in the
+	 * whole UML suddenly dying.  Also, cover negative and
+	 * 1 cases, since they shouldn't happen either.
+	 */
+	if (mmu->id.u.pid < 2) {
+		printk(KERN_ERR "corrupt mm_context - pid = %d\n",
+		       mmu->id.u.pid);
+		return;
 	}
+	os_kill_ptraced_process(mmu->id.u.pid, 1);
 
-	if (skas_needs_stub)
-		free_page(mmu->id.stack);
-
+	free_page(mmu->id.stack);
 	free_ldt(mmu);
 }