linux-kernel - [PATCH 2/2] PCI: imx6: limit DBI register length

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Date:   Wed,  6 Feb 2019 10:57:32 +0100
From:   Stefan Agner <stefan@...er.ch>
To:     lorenzo.pieralisi@....com, jingoohan1@...il.com,
        gustavo.pimentel@...opsys.com, l.stach@...gutronix.de,
        tpiepho@...inj.com
Cc:     leonard.crestez@....com, bhelgaas@...gle.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        stefan@...er.ch
Subject: [PATCH 2/2] PCI: imx6: limit DBI register length

Define the length of the DBI registers. This makes sure that
the kernel does not access registers beyond that point, avoiding
the following abort on a i.MX 6Quad:
  # cat /sys/devices/soc0/soc/1ffc000.pcie/pci0000\:00/0000\:00\:00.0/config
  [  100.021433] Unhandled fault: imprecise external abort (0x1406) at 0xb6ea7000
  ...
  [  100.056423] PC is at dw_pcie_read+0x50/0x84
  [  100.060790] LR is at dw_pcie_rd_own_conf+0x44/0x48
  ...

Signed-off-by: Stefan Agner <stefan@...er.ch>
Reviewed-by: Lucas Stach <l.stach@...gutronix.de>
---
Changes in v3:
- Rebase on pci/dwc
Changes in v4:
- Rebase on pci/dwc
Changes in v5:
- Rebased ontop of pci/dwc
- Use DBI length of 0x200

 drivers/pci/controller/dwc/pci-imx6.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index c1d434ba3642..1ef7be1232f3 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -55,6 +55,7 @@ enum imx6_pcie_variants {
 struct imx6_pcie_drvdata {
 	enum imx6_pcie_variants variant;
 	u32 flags;
+	int dbi_length;
 };
 
 struct imx6_pcie {
@@ -1087,6 +1088,8 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 		break;
 	}
 
+	pci->dbi_length = imx6_pcie->drvdata->dbi_length;
+
 	/* Grab turnoff reset */
 	imx6_pcie->turnoff_reset = devm_reset_control_get_optional_exclusive(dev, "turnoff");
 	if (IS_ERR(imx6_pcie->turnoff_reset)) {
@@ -1170,6 +1173,7 @@ static const struct imx6_pcie_drvdata drvdata[] = {
 		.variant = IMX6Q,
 		.flags = IMX6_PCIE_FLAG_IMX6_PHY |
 			 IMX6_PCIE_FLAG_IMX6_SPEED_CHANGE,
+		.dbi_length = 0x200,
 	},
 	[IMX6SX] = {
 		.variant = IMX6SX,
-- 
2.20.1