1 files changed, 16 insertions, 23 deletions

diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 656fe16c9b63..0eb5a1d3ba70 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -10,14 +10,18 @@
 
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
+#include <asm/mmu_context.h>
 #include <as-layout.h>
 #include <os.h>
 #include <skas.h>
+#include <stub-data.h>
+
+/* Ensure the stub_data struct covers the allocated area */
+static_assert(sizeof(struct stub_data) == STUB_DATA_PAGES * UM_KERN_PAGE_SIZE);
 
 int init_new_context(struct task_struct *task, struct mm_struct *mm)
 {
- 	struct mm_context *from_mm = NULL;
-	struct mm_context *to_mm = &mm->context;
+	struct mm_id *new_id = &mm->context.id;
 	unsigned long stack = 0;
 	int ret = -ENOMEM;
 
@@ -25,34 +29,24 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
 	if (stack == 0)
 		goto out;
 
-	to_mm->id.stack = stack;
-	if (current->mm != NULL && current->mm != &init_mm)
-		from_mm = &current->mm->context;
+	new_id->stack = stack;
 
 	block_signals_trace();
-	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);
+	new_id->pid = start_userspace(stack);
 	unblock_signals_trace();
 
-	if (to_mm->id.u.pid < 0) {
-		ret = to_mm->id.u.pid;
+	if (new_id->pid < 0) {
+		ret = new_id->pid;
 		goto out_free;
 	}
 
-	ret = init_new_ldt(to_mm, from_mm);
-	if (ret < 0) {
-		printk(KERN_ERR "init_new_context_skas - init_ldt"
-		       " failed, errno = %d\n", ret);
-		goto out_free;
-	}
+	/* Ensure the new MM is clean and nothing unwanted is mapped */
+	unmap(new_id, 0, STUB_START);
 
 	return 0;
 
  out_free:
-	if (to_mm->id.stack != 0)
-		free_pages(to_mm->id.stack, ilog2(STUB_DATA_PAGES));
+	free_pages(new_id->stack, ilog2(STUB_DATA_PAGES));
  out:
 	return ret;
 }
@@ -67,13 +61,12 @@ void destroy_context(struct mm_struct *mm)
 	 * whole UML suddenly dying.  Also, cover negative and
 	 * 1 cases, since they shouldn't happen either.
 	 */
-	if (mmu->id.u.pid < 2) {
+	if (mmu->id.pid < 2) {
 		printk(KERN_ERR "corrupt mm_context - pid = %d\n",
-		       mmu->id.u.pid);
+		       mmu->id.pid);
 		return;
 	}
-	os_kill_ptraced_process(mmu->id.u.pid, 1);
+	os_kill_ptraced_process(mmu->id.pid, 1);
 
 	free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES));
-	free_ldt(mmu);
 }