v4.19.13 snapshot.
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
new file mode 100644
index 0000000..0b63d68
--- /dev/null
+++ b/fs/proc/task_nommu.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mm.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/fs_struct.h>
+#include <linux/mount.h>
+#include <linux/ptrace.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/sched/mm.h>
+
+#include "internal.h"
+
+/*
+ * Logic: we've got two memory sums for each process, "shared", and
+ * "non-shared". Shared memory may get counted more than once, for
+ * each process that owns it. Non-shared memory is counted
+ * accurately.
+ */
+void task_mem(struct seq_file *m, struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ struct vm_region *region;
+ struct rb_node *p;
+ unsigned long bytes = 0, sbytes = 0, slack = 0, size;
+
+ down_read(&mm->mmap_sem);
+ for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
+ vma = rb_entry(p, struct vm_area_struct, vm_rb);
+
+ bytes += kobjsize(vma);
+
+ region = vma->vm_region;
+ if (region) {
+ size = kobjsize(region);
+ size += region->vm_end - region->vm_start;
+ } else {
+ size = vma->vm_end - vma->vm_start;
+ }
+
+ if (atomic_read(&mm->mm_count) > 1 ||
+ vma->vm_flags & VM_MAYSHARE) {
+ sbytes += size;
+ } else {
+ bytes += size;
+ if (region)
+ slack = region->vm_end - vma->vm_end;
+ }
+ }
+
+ if (atomic_read(&mm->mm_count) > 1)
+ sbytes += kobjsize(mm);
+ else
+ bytes += kobjsize(mm);
+
+ if (current->fs && current->fs->users > 1)
+ sbytes += kobjsize(current->fs);
+ else
+ bytes += kobjsize(current->fs);
+
+ if (current->files && atomic_read(¤t->files->count) > 1)
+ sbytes += kobjsize(current->files);
+ else
+ bytes += kobjsize(current->files);
+
+ if (current->sighand && atomic_read(¤t->sighand->count) > 1)
+ sbytes += kobjsize(current->sighand);
+ else
+ bytes += kobjsize(current->sighand);
+
+ bytes += kobjsize(current); /* includes kernel stack */
+
+ seq_printf(m,
+ "Mem:\t%8lu bytes\n"
+ "Slack:\t%8lu bytes\n"
+ "Shared:\t%8lu bytes\n",
+ bytes, slack, sbytes);
+
+ up_read(&mm->mmap_sem);
+}
+
+unsigned long task_vsize(struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ struct rb_node *p;
+ unsigned long vsize = 0;
+
+ down_read(&mm->mmap_sem);
+ for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
+ vma = rb_entry(p, struct vm_area_struct, vm_rb);
+ vsize += vma->vm_end - vma->vm_start;
+ }
+ up_read(&mm->mmap_sem);
+ return vsize;
+}
+
+unsigned long task_statm(struct mm_struct *mm,
+ unsigned long *shared, unsigned long *text,
+ unsigned long *data, unsigned long *resident)
+{
+ struct vm_area_struct *vma;
+ struct vm_region *region;
+ struct rb_node *p;
+ unsigned long size = kobjsize(mm);
+
+ down_read(&mm->mmap_sem);
+ for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
+ vma = rb_entry(p, struct vm_area_struct, vm_rb);
+ size += kobjsize(vma);
+ region = vma->vm_region;
+ if (region) {
+ size += kobjsize(region);
+ size += region->vm_end - region->vm_start;
+ }
+ }
+
+ *text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
+ >> PAGE_SHIFT;
+ *data = (PAGE_ALIGN(mm->start_stack) - (mm->start_data & PAGE_MASK))
+ >> PAGE_SHIFT;
+ up_read(&mm->mmap_sem);
+ size >>= PAGE_SHIFT;
+ size += *text + *data;
+ *resident = size;
+ return size;
+}
+
+static int is_stack(struct vm_area_struct *vma)
+{
+ struct mm_struct *mm = vma->vm_mm;
+
+ /*
+ * We make no effort to guess what a given thread considers to be
+ * its "stack". It's not even well-defined for programs written
+ * languages like Go.
+ */
+ return vma->vm_start <= mm->start_stack &&
+ vma->vm_end >= mm->start_stack;
+}
+
+/*
+ * display a single VMA to a sequenced file
+ */
+static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long ino = 0;
+ struct file *file;
+ dev_t dev = 0;
+ int flags;
+ unsigned long long pgoff = 0;
+
+ flags = vma->vm_flags;
+ file = vma->vm_file;
+
+ if (file) {
+ struct inode *inode = file_inode(vma->vm_file);
+ dev = inode->i_sb->s_dev;
+ ino = inode->i_ino;
+ pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
+ }
+
+ seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
+ seq_printf(m,
+ "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+ vma->vm_start,
+ vma->vm_end,
+ flags & VM_READ ? 'r' : '-',
+ flags & VM_WRITE ? 'w' : '-',
+ flags & VM_EXEC ? 'x' : '-',
+ flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
+ pgoff,
+ MAJOR(dev), MINOR(dev), ino);
+
+ if (file) {
+ seq_pad(m, ' ');
+ seq_file_path(m, file, "");
+ } else if (mm && is_stack(vma)) {
+ seq_pad(m, ' ');
+ seq_printf(m, "[stack]");
+ }
+
+ seq_putc(m, '\n');
+ return 0;
+}
+
+/*
+ * display mapping lines for a particular process's /proc/pid/maps
+ */
+static int show_map(struct seq_file *m, void *_p)
+{
+ struct rb_node *p = _p;
+
+ return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb));
+}
+
+static void *m_start(struct seq_file *m, loff_t *pos)
+{
+ struct proc_maps_private *priv = m->private;
+ struct mm_struct *mm;
+ struct rb_node *p;
+ loff_t n = *pos;
+
+ /* pin the task and mm whilst we play with them */
+ priv->task = get_proc_task(priv->inode);
+ if (!priv->task)
+ return ERR_PTR(-ESRCH);
+
+ mm = priv->mm;
+ if (!mm || !mmget_not_zero(mm))
+ return NULL;
+
+ down_read(&mm->mmap_sem);
+ /* start from the Nth VMA */
+ for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
+ if (n-- == 0)
+ return p;
+
+ up_read(&mm->mmap_sem);
+ mmput(mm);
+ return NULL;
+}
+
+static void m_stop(struct seq_file *m, void *_vml)
+{
+ struct proc_maps_private *priv = m->private;
+
+ if (!IS_ERR_OR_NULL(_vml)) {
+ up_read(&priv->mm->mmap_sem);
+ mmput(priv->mm);
+ }
+ if (priv->task) {
+ put_task_struct(priv->task);
+ priv->task = NULL;
+ }
+}
+
+static void *m_next(struct seq_file *m, void *_p, loff_t *pos)
+{
+ struct rb_node *p = _p;
+
+ (*pos)++;
+ return p ? rb_next(p) : NULL;
+}
+
+static const struct seq_operations proc_pid_maps_ops = {
+ .start = m_start,
+ .next = m_next,
+ .stop = m_stop,
+ .show = show_map
+};
+
+static int maps_open(struct inode *inode, struct file *file,
+ const struct seq_operations *ops)
+{
+ struct proc_maps_private *priv;
+
+ priv = __seq_open_private(file, ops, sizeof(*priv));
+ if (!priv)
+ return -ENOMEM;
+
+ priv->inode = inode;
+ priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
+ if (IS_ERR(priv->mm)) {
+ int err = PTR_ERR(priv->mm);
+
+ seq_release_private(inode, file);
+ return err;
+ }
+
+ return 0;
+}
+
+
+static int map_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *seq = file->private_data;
+ struct proc_maps_private *priv = seq->private;
+
+ if (priv->mm)
+ mmdrop(priv->mm);
+
+ return seq_release_private(inode, file);
+}
+
+static int pid_maps_open(struct inode *inode, struct file *file)
+{
+ return maps_open(inode, file, &proc_pid_maps_ops);
+}
+
+const struct file_operations proc_pid_maps_operations = {
+ .open = pid_maps_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = map_release,
+};
+