1 files changed, 50 insertions, 0 deletions
diff --git a/arch/x86/um/mem_32.c b/arch/x86/um/mem_32.c
new file mode 100644
index 000000000..29b2203bc
--- /dev/null
+++ b/arch/x86/um/mem_32.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
+ */
+
+#include <linux/mm.h>
+#include <asm/elf.h>
+
+static struct vm_area_struct gate_vma;
+
+static int __init gate_vma_init(void)
+{
+	if (!FIXADDR_USER_START)
+		return 0;
+
+	vma_init(&gate_vma, NULL);
+	gate_vma.vm_start = FIXADDR_USER_START;
+	gate_vma.vm_end = FIXADDR_USER_END;
+	vm_flags_init(&gate_vma, VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC);
+	gate_vma.vm_page_prot = PAGE_READONLY;
+
+	return 0;
+}
+__initcall(gate_vma_init);
+
+struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
+{
+	return FIXADDR_USER_START ? &gate_vma : NULL;
+}
+
+int in_gate_area_no_mm(unsigned long addr)
+{
+	if (!FIXADDR_USER_START)
+		return 0;
+
+	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
+		return 1;
+
+	return 0;
+}
+
+int in_gate_area(struct mm_struct *mm, unsigned long addr)
+{
+	struct vm_area_struct *vma = get_gate_vma(mm);
+
+	if (!vma)
+		return 0;
+
+	return (addr >= vma->vm_start) && (addr < vma->vm_end);
+}