[PATCH 2/3] e820_update_range(): Allow specifying ULLONG_MAX

[Bernhard Walle <bwalle@suse.de>]

Allow the specifying of ULLONG_MAX to limit the whole E820 map from the
specified start to the end. Without the patch, there would be integer
overflows.


Signed-off-by: Bernhard Walle <bwalle@suse.de>
---
 arch/x86/kernel/e820.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index e466073..7d1109b 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -397,6 +397,9 @@ int __init copy_e820_map(struct e820entry *biosmap, int nr_map)
 	return __copy_e820_map(biosmap, nr_map);
 }
 
+/*
+ * Pass size == ULLONG_MAX to update until the end.
+ */
 u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
 				unsigned new_type)
 {
@@ -412,14 +415,18 @@ u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
 			continue;
 		/* totally covered? */
 		if (ei->addr >= start &&
-		    (ei->addr + ei->size) <= (start + size)) {
+		    (((ei->addr + ei->size) <= (start + size)) ||
+			    (size == ULLONG_MAX))) {
 			ei->type = new_type;
 			real_updated_size += ei->size;
 			continue;
 		}
 		/* partially covered */
 		final_start = max(start, ei->addr);
-		final_end = min(start + size, ei->addr + ei->size);
+		if (size == ULLONG_MAX)
+			final_end = ei->addr + ei->size;
+		else
+			final_end = min(start + size, ei->addr + ei->size);
 		if (final_start >= final_end)
 			continue;
 		ei->size -= final_end - final_start;
-- 
1.5.4.5