1 files changed, 86 insertions, 0 deletions

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
new file mode 100644
index 000000000000..72d13b0779a2
--- /dev/null
+++ b/arch/x86/mm/mpx.c
@@ -0,0 +1,86 @@
+/*
+ * mpx.c - Memory Protection eXtensions
+ *
+ * Copyright (c) 2014, Intel Corporation.
+ * Qiaowei Ren <qiaowei.ren@intel.com>
+ * Dave Hansen <dave.hansen@intel.com>
+ */
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/sched/sysctl.h>
+
+#include <asm/mman.h>
+#include <asm/mpx.h>
+
+static const char *mpx_mapping_name(struct vm_area_struct *vma)
+{
+        return "[mpx]";
+}
+
+static struct vm_operations_struct mpx_vma_ops = {
+        .name = mpx_mapping_name,
+};
+
+/*
+ * This is really a simplified "vm_mmap". it only handles MPX
+ * bounds tables (the bounds directory is user-allocated).
+ *
+ * Later on, we use the vma->vm_ops to uniquely identify these
+ * VMAs.
+ */
+static unsigned long mpx_mmap(unsigned long len)
+{
+        unsigned long ret;
+        unsigned long addr, pgoff;
+        struct mm_struct *mm = current->mm;
+        vm_flags_t vm_flags;
+        struct vm_area_struct *vma;
+
+        /* Only bounds table and bounds directory can be allocated here */
+        if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES)
+                return -EINVAL;
+
+        down_write(&mm->mmap_sem);
+
+        /* Too many mappings? */
+        if (mm->map_count > sysctl_max_map_count) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        /* Obtain the address to map to. we verify (or select) it and ensure
+         * that it represents a valid section of the address space.
+         */
+        addr = get_unmapped_area(NULL, 0, len, 0, MAP_ANONYMOUS | MAP_PRIVATE);
+        if (addr & ~PAGE_MASK) {
+                ret = addr;
+                goto out;
+        }
+
+        vm_flags = VM_READ | VM_WRITE | VM_MPX |
+                        mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+
+        /* Set pgoff according to addr for anon_vma */
+        pgoff = addr >> PAGE_SHIFT;
+
+        ret = mmap_region(NULL, addr, len, vm_flags, pgoff);
+        if (IS_ERR_VALUE(ret))
+                goto out;
+
+        vma = find_vma(mm, ret);
+        if (!vma) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        vma->vm_ops = &mpx_vma_ops;
+
+        if (vm_flags & VM_LOCKED) {
+                up_write(&mm->mmap_sem);
+                mm_populate(ret, len);
+                return ret;
+        }
+
+out:
+        up_write(&mm->mmap_sem);
+        return ret;
+}