v4.19.13 snapshot.
diff --git a/kernel/range.c b/kernel/range.c
new file mode 100644
index 0000000..d84de67
--- /dev/null
+++ b/kernel/range.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Range add and subtract
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/sort.h>
+#include <linux/string.h>
+#include <linux/range.h>
+
+int add_range(struct range *range, int az, int nr_range, u64 start, u64 end)
+{
+ if (start >= end)
+ return nr_range;
+
+ /* Out of slots: */
+ if (nr_range >= az)
+ return nr_range;
+
+ range[nr_range].start = start;
+ range[nr_range].end = end;
+
+ nr_range++;
+
+ return nr_range;
+}
+
+int add_range_with_merge(struct range *range, int az, int nr_range,
+ u64 start, u64 end)
+{
+ int i;
+
+ if (start >= end)
+ return nr_range;
+
+ /* get new start/end: */
+ for (i = 0; i < nr_range; i++) {
+ u64 common_start, common_end;
+
+ if (!range[i].end)
+ continue;
+
+ common_start = max(range[i].start, start);
+ common_end = min(range[i].end, end);
+ if (common_start > common_end)
+ continue;
+
+ /* new start/end, will add it back at last */
+ start = min(range[i].start, start);
+ end = max(range[i].end, end);
+
+ memmove(&range[i], &range[i + 1],
+ (nr_range - (i + 1)) * sizeof(range[i]));
+ range[nr_range - 1].start = 0;
+ range[nr_range - 1].end = 0;
+ nr_range--;
+ i--;
+ }
+
+ /* Need to add it: */
+ return add_range(range, az, nr_range, start, end);
+}
+
+void subtract_range(struct range *range, int az, u64 start, u64 end)
+{
+ int i, j;
+
+ if (start >= end)
+ return;
+
+ for (j = 0; j < az; j++) {
+ if (!range[j].end)
+ continue;
+
+ if (start <= range[j].start && end >= range[j].end) {
+ range[j].start = 0;
+ range[j].end = 0;
+ continue;
+ }
+
+ if (start <= range[j].start && end < range[j].end &&
+ range[j].start < end) {
+ range[j].start = end;
+ continue;
+ }
+
+
+ if (start > range[j].start && end >= range[j].end &&
+ range[j].end > start) {
+ range[j].end = start;
+ continue;
+ }
+
+ if (start > range[j].start && end < range[j].end) {
+ /* Find the new spare: */
+ for (i = 0; i < az; i++) {
+ if (range[i].end == 0)
+ break;
+ }
+ if (i < az) {
+ range[i].end = range[j].end;
+ range[i].start = end;
+ } else {
+ pr_err("%s: run out of slot in ranges\n",
+ __func__);
+ }
+ range[j].end = start;
+ continue;
+ }
+ }
+}
+
+static int cmp_range(const void *x1, const void *x2)
+{
+ const struct range *r1 = x1;
+ const struct range *r2 = x2;
+
+ if (r1->start < r2->start)
+ return -1;
+ if (r1->start > r2->start)
+ return 1;
+ return 0;
+}
+
+int clean_sort_range(struct range *range, int az)
+{
+ int i, j, k = az - 1, nr_range = az;
+
+ for (i = 0; i < k; i++) {
+ if (range[i].end)
+ continue;
+ for (j = k; j > i; j--) {
+ if (range[j].end) {
+ k = j;
+ break;
+ }
+ }
+ if (j == i)
+ break;
+ range[i].start = range[k].start;
+ range[i].end = range[k].end;
+ range[k].start = 0;
+ range[k].end = 0;
+ k--;
+ }
+ /* count it */
+ for (i = 0; i < az; i++) {
+ if (!range[i].end) {
+ nr_range = i;
+ break;
+ }
+ }
+
+ /* sort them */
+ sort(range, nr_range, sizeof(struct range), cmp_range, NULL);
+
+ return nr_range;
+}
+
+void sort_range(struct range *range, int nr_range)
+{
+ /* sort them */
+ sort(range, nr_range, sizeof(struct range), cmp_range, NULL);
+}