[PATCH 1/3] of: ignore sub-page memory regions

From: Mike Rapoport
Date: Wed Jul 04 2018 - 09:18:39 EST


Memory region size is rounded down to page boundary and with sub-page
region it becomes 0 and there is no point to add an empty region.
Moreover, when the base is less than PAGE_SIZE we get a bogus size as
(base + size - 1) evaluates to -1.

The commit 8cccffc52694 ("of: check for size < 0 after rounding in
early_init_dt_add_memory_arch") introduced a test for wrap around for the
case when base is not page aligned, the same test can be used to ignore
sub-page region sizes.

Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
---
drivers/of/fdt.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 6da20b9..e866745 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1134,12 +1134,13 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
{
const u64 phys_offset = MIN_MEMBLOCK_ADDR;

+ if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
+ pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
+ base, base + size);
+ return;
+ }
+
if (!PAGE_ALIGNED(base)) {
- if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
- pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
- base, base + size);
- return;
- }
size -= PAGE_SIZE - (base & ~PAGE_MASK);
base = PAGE_ALIGN(base);
}
--
2.7.4