linux-kernel - [PATCH] dma-mapping: Fix 32-bit overflow with CONFIG_ARM

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Date:   Mon, 26 Oct 2020 16:27:55 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Jim Quinlan <james.quinlan@...adcom.com>,
        Christoph Hellwig <hch@....de>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH] dma-mapping: Fix 32-bit overflow with CONFIG_ARM_LPAE=n

On r8a7791/koelsch and shmobile_defconfig, PCIe probing fails with:

    rcar-pcie fe000000.pcie: Adjusted size 0x0 invalid
    rcar-pcie: probe of fe000000.pcie failed with error -22

of_dma_get_range() returns the following map:

    cpu_start 0x40000000 dma_start 0x40000000 size 0x080000000 offset 0
    cpu_start 0x00000000 dma_start 0x00000000 size 0x100000000 offset 0

If CONFIG_ARM_LPAE=n, dma_addr_t is 32-bit.  Hence when assigning
r->dma_start + r->size to dma_end, this value will be truncated to
32-bit, yielding zero when processing the second table entry.
Consequently, both dma_start and dma_end will be zero, leading to a zero
size.

Fix this by changing the dma_start and dma_end variables from dma_addr_t
to u64.

Fixes: e0d072782c734d27 ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 drivers/of/device.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 655dee422563f05f..3a469c79e6b05de4 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -93,7 +93,7 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
 {
 	const struct iommu_ops *iommu;
 	const struct bus_dma_region *map = NULL;
-	dma_addr_t dma_start = 0;
+	u64 dma_start = 0;
 	u64 mask, end, size = 0;
 	bool coherent;
 	int ret;
@@ -109,10 +109,10 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
 			return ret == -ENODEV ? 0 : ret;
 	} else {
 		const struct bus_dma_region *r = map;
-		dma_addr_t dma_end = 0;
+		u64 dma_end = 0;
 
 		/* Determine the overall bounds of all DMA regions */
-		for (dma_start = ~(dma_addr_t)0; r->size; r++) {
+		for (dma_start = ~0ULL; r->size; r++) {
 			/* Take lower and upper limits */
 			if (r->dma_start < dma_start)
 				dma_start = r->dma_start;
-- 
2.25.1