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 | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
kexec/mem_regions.h | 4 ++++
2 files changed, 59 insertions(+)
diff --git a/kexec/mem_regions.c b/kexec/mem_regions.c
index 804984a..c6ba942 100644
--- a/kexec/mem_regions.c
+++ b/kexec/mem_regions.c
@@ -29,6 +29,61 @@ void mem_regions_sort(struct memory_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;
+
+ 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) {
+ /* 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 {
+ struct memory_range *new;
+
+ /*
+ * Split this area into 2 smaller ones and
+ * remove excluded range from between. First
+ * create new entry for the remaining area.
+ */
+ if (ranges->size >= ranges->max_size)
+ return -1;
+
+ new = ranges->ranges + ranges->size++;
+ new->start = range->end + 1;
+ new->end = r->end;
+
+ /*
+ * Update this area to end before excluded
+ * range.
+ */
+ r->end = range->start - 1;
+ break;
+ }
+ }
+ }
+ return 0;
+}
+
+/**
* mem_regions_add() - add a memory region to a set of ranges
* @ranges: ranges to add the memory region to
* @max: maximum number of entries in memory region
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
