[PATCH 1/1] drivers: dma-contiguous: Ensure cma reserve region never cross the low/high mem boundary

From: Jason Liu
Date: Wed Nov 16 2016 - 03:00:52 EST


If the cma reserve region goes through the device-tree method,
also need ensure the cma reserved region not cross the low/high
mem boundary. This patch did the similar fix as commit:16195dd
("mm: cma: Ensure that reservations never cross the low/high mem boundary")

Signed-off-by: Jason Liu <jason.hui.liu@xxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/dma-contiguous.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index e167a1e1..2bc093c 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -244,6 +244,7 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
{
phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
phys_addr_t mask = align - 1;
+ phys_addr_t highmem_start;
unsigned long node = rmem->fdt_node;
struct cma *cma;
int err;
@@ -256,6 +257,32 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
pr_err("Reserved memory: incorrect alignment of CMA region\n");
return -EINVAL;
}
+#ifdef CONFIG_X86
+ /*
+ * high_memory isn't direct mapped memory so retrieving its physical
+ * address isn't appropriate. But it would be useful to check the
+ * physical address of the highmem boundary so it's justfiable to get
+ * the physical address from it. On x86 there is a validation check for
+ * this case, so the following workaround is needed to avoid it.
+ */
+ highmem_start = __pa_nodebug(high_memory);
+#else
+ highmem_start = __pa(high_memory);
+#endif
+
+ /*
+ * All pages in the reserved area must come from the same zone.
+ * If the reserved region crosses the low/high memory boundary,
+ * try to fix it up and then fall back to allocate from the low mem
+ */
+ if (rmem->base < highmem_start &&
+ (rmem->base + rmem->size) > highmem_start) {
+ memblock_free(rmem->base, rmem->size);
+ rmem->base = memblock_alloc_range(rmem->size, align, 0,
+ highmem_start, MEMBLOCK_NONE);
+ if (!rmem->base)
+ return -ENOMEM;
+ }

err = cma_init_reserved_mem(rmem->base, rmem->size, 0, &cma);
if (err) {
--
1.9.1