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diff --git a/sys/kern/subr_physmem.c b/sys/kern/subr_physmem.c
--- a/sys/kern/subr_physmem.c
+++ b/sys/kern/subr_physmem.c
@@ -270,6 +270,67 @@
return (acnt);
}
+/*
+ * Check if the region at idx can be merged with the region above it.
+ */
+static size_t
+merge_upper_regions(struct region *regions, size_t rcnt, size_t idx)
+{
+ struct region *lower, *upper;
+ vm_paddr_t lend, uend;
+ size_t i, mergecnt, movecnt;
+
+ lower = &regions[idx];
+ lend = lower->addr + lower->size;
+
+ /*
+ * Continue merging in upper entries as long as we have entries to
+ * merge; the new block could have spanned more than one, although one
+ * is likely the common case.
+ */
+ for (i = idx + 1; i < rcnt; i++) {
+ upper = &regions[i];
+ if (lend < upper->addr || lower->flags != upper->flags)
+ break;
+
+ uend = upper->addr + upper->size;
+ if (uend > lend) {
+ lower->size += uend - lend;
+ lend = lower->addr + lower->size;
+ }
+
+ if (uend >= lend) {
+ /*
+ * If we didn't move past the end of the upper region,
+ * then we don't need to bother checking for another
+ * merge because it would have been done already. Just
+ * increment i once more to maintain the invariant that
+ * i is one past the last entry merged.
+ */
+ i++;
+ break;
+ }
+ }
+
+ /*
+ * We merged in the entries from [idx + 1, i); physically move the tail
+ * end at [i, rcnt) if we need to.
+ */
+ mergecnt = i - (idx + 1);
+ if (mergecnt > 0) {
+ movecnt = rcnt - i;
+ if (movecnt == 0) {
+ /* Merged all the way to the end, just decrease rcnt. */
+ rcnt = idx + 1;
+ } else {
+ memmove(&regions[idx + 1], &regions[idx + mergecnt + 1],
+ movecnt * sizeof(*regions));
+ rcnt -= mergecnt;
+ }
+ }
+ return (rcnt);
+}
+
/*
* Insertion-sort a new entry into a regions list; sorted by start address.
*/
@@ -278,19 +339,38 @@
vm_size_t size, uint32_t flags)
{
size_t i;
+ vm_paddr_t nend, rend;
struct region *ep, *rp;
+ nend = addr + size;
ep = regions + rcnt;
for (i = 0, rp = regions; i < rcnt; ++i, ++rp) {
- if (rp->addr == addr && rp->size == size) /* Pure dup. */
- return (rcnt);
if (flags == rp->flags) {
- if (addr + size == rp->addr) {
+ rend = rp->addr + rp->size;
+ if (addr <= rp->addr && nend >= rp->addr) {
+ /*
+ * New mapping overlaps at the beginning, shift
+ * for any difference in the beginning then
+ * shift if the new mapping extends past.
+ */
+ rp->size += rp->addr - addr;
rp->addr = addr;
- rp->size += size;
+ if (nend > rend) {
+ rp->size += nend - rend;
+ rcnt = merge_upper_regions(regions,
+ rcnt, i);
+ }
return (rcnt);
- } else if (rp->addr + rp->size == addr) {
- rp->size += size;
+ } else if (addr <= rend && nend > rp->addr) {
+ /*
+ * New mapping is either entirely contained
+ * within or it's overlapping at the end.
+ */
+ if (nend > rend) {
+ rp->size += nend - rend;
+ rcnt = merge_upper_regions(regions,
+ rcnt, i);
+ }
return (rcnt);
}
}

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