Add a helper to exclude a region from a set of memory ranges.
Signed-off-by: Russell King <rmk at arm.linux.org.uk>
---
kexec/mem_regions.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++
kexec/mem_regions.h | 4 +++
2 files changed, 75 insertions(+)
diff --git a/kexec/mem_regions.c b/kexec/mem_regions.c
index 804984a..b01a5c8 100644
--- a/kexec/mem_regions.c
+++ b/kexec/mem_regions.c
@@ -55,3 +55,74 @@ int mem_regions_add(struct memory_ranges *ranges, unsigned long long base,
return 0;
}
+static void mem_regions_remove(struct memory_ranges *ranges, int index)
+{
+ int tail_entries;
+
+ /* we are assured to have at least one entry */
+ ranges->size -= 1;
+
+ /* if we have following entries, shuffle them down one place */
+ tail_entries = ranges->size - index;
+ if (tail_entries)
+ memmove(ranges->ranges + index, ranges->ranges + index + 1,
+ tail_entries * sizeof(*ranges->ranges));
+
+ /* zero the new tail entry */
+ memset(ranges->ranges + ranges->size, 0, sizeof(*ranges->ranges));
+}
+
+/**
+ * mem_regions_exclude() - excludes a memory region from a set of memory ranges
+ * @ranges: memory ranges to exclude the region from
+ * @range: memory range to exclude
+ *
+ * Exclude a memory region from a set of memory ranges. We assume that
+ * the region to be excluded is either wholely located within one of the
+ * memory ranges, or not at all.
+ */
+int mem_regions_exclude(struct memory_ranges *ranges,
+ const struct memory_range *range)
+{
+ int i, ret;
+
+ for (i = 0; i < ranges->size; i++) {
+ struct memory_range *r = ranges->ranges + i;
+
+ /*
+ * We assume that crash area is fully contained in
+ * some larger memory area.
+ */
+ if (r->start <= range->start && r->end >= range->end) {
+ if (r->start == range->start) {
+ if (r->end == range->end)
+ /* Remove this entry */
+ mem_regions_remove(ranges, i);
+ else
+ /* Shrink the start of this memory range */
+ r->start = range->end + 1;
+ } else if (r->end == range->end) {
+ /* Shrink the end of this memory range */
+ r->end = range->start - 1;
+ } else {
+ /*
+ * Split this area into 2 smaller ones and
+ * remove excluded range from between. First
+ * create new entry for the remaining area.
+ */
+ ret = mem_regions_add(ranges, range->end + 1,
+ r->end - range->end, 0);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * Update this area to end before excluded
+ * range.
+ */
+ r->end = range->start - 1;
+ break;
+ }
+ }
+ }
+ return 0;
+}
diff --git a/kexec/mem_regions.h b/kexec/mem_regions.h
index da7b5e8..ae9e972 100644
--- a/kexec/mem_regions.h
+++ b/kexec/mem_regions.h
@@ -2,9 +2,13 @@
#define MEM_REGIONS_H
struct memory_ranges;
+struct memory_range;
void mem_regions_sort(struct memory_ranges *ranges);
+int mem_regions_exclude(struct memory_ranges *ranges,
+ const struct memory_range *range);
+
int mem_regions_add(struct memory_ranges *ranges, unsigned long long base,
unsigned long long length, int type);
--
1.9.1
