This is a fix for 12a3efa846b574070f90aa0c22c3f3e67cca10c4. That
commit correctly scanned the entire DIRECTMAP memory segment for the
largest heap but did not take into consideration the memory
'availability' of different portions of that segment. In consequence
the heap could be formed of 'reserved' memory regions with severe
consequences.
---
i386/i386at/biosmem.c | 41 ++++++++++++++++++++++++++++++++++-------
1 file changed, 34 insertions(+), 7 deletions(-)
diff --git a/i386/i386at/biosmem.c b/i386/i386at/biosmem.c
index 5e9e2ce4..e0820b05 100644
--- a/i386/i386at/biosmem.c
+++ b/i386/i386at/biosmem.c
@@ -629,19 +629,45 @@ static void __boot
biosmem_setup_allocator(void)
{
phys_addr_t heap_start, heap_end, max_heap_start, max_heap_end;
- phys_addr_t start, end;
- int error;
+ const struct biosmem_map_entry *entry, *map_end;
+ const phys_addr_t heap_search_start = BIOSMEM_END;
+ const phys_addr_t heap_search_end = VM_PAGE_DIRECTMAP_LIMIT;
/*
- * Find some memory for the heap. Look for the largest unused area in
- * upper memory, carefully avoiding all boot data.
+ * Find some memory for the heap. Look for the largest unused and
+ * available area in the range heap_search_start to
+ * heap_search_end, carefully avoiding all boot data.
*/
+ map_end = biosmem_map + biosmem_map_size;
max_heap_start = 0;
max_heap_end = 0;
- start = BIOSMEM_END;
- end = VM_PAGE_DIRECTMAP_LIMIT;
- for (;;) {
+ for (entry = biosmem_map; entry < map_end; entry++)
+ {
+ phys_addr_t start, end;
+ int error;
+
+ /* biosmem_map entries are sorted by base address so we can
+ stop searching if... */
+ if (entry->base_addr >= heap_search_end)
+ break;
+
+ if (entry->type != BIOSMEM_TYPE_AVAILABLE)
+ continue;
+
+ start = entry->base_addr;
+ end = start + entry->length;
+
+ if (end <= heap_search_start)
+ continue;
+
+ if (start < heap_search_start)
+ start = heap_search_start;
+
+ if (end > heap_search_end)
+ end = heap_search_end;
+
+ for (;;) {
error = biosmem_find_avail(start, end, &heap_start, &heap_end);
if (error) {
@@ -654,6 +680,7 @@ biosmem_setup_allocator(void)
}
start = heap_end;
+ }
}
if (max_heap_start >= max_heap_end)
--
2.47.3
