[U-Boot] [PATCH 20/27] image: Use ram_top, not bi_memsize, in getenv_bootm_size

[Paul Burton]

When determining the region of memory to allow for use by bootm, using
bi_memstart & adding bi_memsize can cause problems if that leads to an
integer overflow. For example on some MIPS systems bi_memstart would be
0xffffffff80000000 (ie. the start of the MIPS ckseg0 region) and if the
system has 2GB of memory then the addition would wrap around to 0.

The maximum amount of memory to be used by U-Boot is already accounted
for by the ram_top field of struct global_data, so make use of that for
the calculation instead.

Signed-off-by: Paul Burton <paul.burton at imgtec.com>
---

 common/image.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/common/image.c b/common/image.c
index 1581022..25e632b 100644
--- a/common/image.c
+++ b/common/image.c
@@ -489,7 +489,7 @@ phys_size_t getenv_bootm_size(void)
 	size = gd->bd->bi_dram[0].size;
 #else
 	start = (ulong)phys_to_virt(gd->bd->bi_memstart);
-	size = gd->bd->bi_memsize;
+	size = gd->ram_top - start;
 #endif
 
 	s = getenv("bootm_low");
-- 
2.10.0