x86: Move range related operation to one file

We have almost the same code for mtrr cleanup and amd_bus checkup, and
this code  will also be used in replacing bootmem with early_res,
so try to move them together and reuse it from different parts.

Also rename update_range to subtract_range as that is what the
function is actually doing.

-v2: update comments as Christoph requested

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1265793639-15071-4-git-send-email-yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 163 insertions, 0 deletions

diff --git a/kernel/range.c b/kernel/range.c
new file mode 100644
index 000000000000..71e0021281fe
--- /dev/null
+++ b/kernel/range.c
@@ -0,0 +1,163 @@
+/*
+ * Range add and subtract
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sort.h>
+
+#include <linux/range.h>
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+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;
+
+        /* Try to merge it with old one: */
+        for (i = 0; i < nr_range; i++) {
+                u64 final_start, final_end;
+                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 + 1)
+                        continue;
+
+                final_start = min(range[i].start, start);
+                final_end = max(range[i].end, end);
+
+                range[i].start = final_start;
+                range[i].end =  final_end;
+                return nr_range;
+        }
+
+        /* 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 + 1) {
+                        range[j].start = end + 1;
+                        continue;
+                }
+
+
+                if (start > range[j].start && end >= range[j].end &&
+                    range[j].end > start - 1) {
+                        range[j].end = start - 1;
+                        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 + 1;
+                        } else {
+                                printk(KERN_ERR "run of slot in ranges\n");
+                        }
+                        range[j].end = start - 1;
+                        continue;
+                }
+        }
+}
+
+static int cmp_range(const void *x1, const void *x2)
+{
+        const struct range *r1 = x1;
+        const struct range *r2 = x2;
+        s64 start1, start2;
+
+        start1 = r1->start;
+        start2 = r2->start;
+
+        return start1 - start2;
+}
+
+int clean_sort_range(struct range *range, int az)
+{
+        int i, j, k = az - 1, nr_range = 0;
+
+        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);
+}