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Message-Id: <1443811443-18878-5-git-send-email-ddaney.cavm@gmail.com> Date: Fri, 2 Oct 2015 11:44:02 -0700 From: David Daney <ddaney.cavm@...il.com> To: linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org, Will Deacon <will.deacon@....com>, Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>, Mark Rutland <mark.rutland@....com>, Ian Campbell <ijc+devicetree@...lion.org.uk>, Kumar Gala <galak@...eaurora.org>, linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, Marc Zyngier <marc.zyngier@....com> Cc: David Daney <david.daney@...ium.com> Subject: [PATCH v4 4/5] PCI: generic: Correct, and avoid overflow, in bus_max calculation. From: David Daney <david.daney@...ium.com> There are two problems with the bus_max calculation: 1) The u8 data type can overflow for large config space windows. 2) The calculation is incorrect for a bus range that doesn't start at zero. Since the configuration space is relative to bus zero, make bus_max just be the size of the config window scaled by bus_shift. Then clamp it to a maximum of 255, per PCI. Use a data type of int to avoid overflow problems. Update host-generic-pci.txt to clarify the semantics of the "reg" property with respect to non-zero starting bus numbers. Signed-off-by: David Daney <david.daney@...ium.com> --- Change from V3: Add to explanation of "reg" property in host-generic-pci.txt. Add error message if "reg" property is too big. Documentation/devicetree/bindings/pci/host-generic-pci.txt | 6 +++++- drivers/pci/host/pci-host-generic.c | 12 +++++++++--- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/Documentation/devicetree/bindings/pci/host-generic-pci.txt b/Documentation/devicetree/bindings/pci/host-generic-pci.txt index cf3e205..42303bb 100644 --- a/Documentation/devicetree/bindings/pci/host-generic-pci.txt +++ b/Documentation/devicetree/bindings/pci/host-generic-pci.txt @@ -34,7 +34,11 @@ Properties of the host controller node: - #size-cells : Must be 2. - reg : The Configuration Space base address and size, as accessed - from the parent bus. + from the parent bus. The base address corresponds to + bus zero, even though the "bus-range" property may specify + a different starting bus number. The driver must only map + or access the portion of the Configuration Space that + corresponds to the "bus-range" Properties of the /chosen node: diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c index 216ded5..5cce837 100644 --- a/drivers/pci/host/pci-host-generic.c +++ b/drivers/pci/host/pci-host-generic.c @@ -164,7 +164,7 @@ out_release_res: static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci) { int err; - u8 bus_max; + int bus_max; resource_size_t busn; struct resource *bus_range; struct device *dev = pci->host.dev.parent; @@ -177,8 +177,14 @@ static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci) } /* Limit the bus-range to fit within reg */ - bus_max = pci->cfg.bus_range->start + - (resource_size(&pci->cfg.res) >> pci->cfg.ops->bus_shift) - 1; + bus_max = (resource_size(&pci->cfg.res) >> pci->cfg.ops->bus_shift) - 1; + if (bus_max > 255) { + dev_err(dev, + "\"reg\" size corresponds to bus %d, truncating to 255\n", + bus_max); + bus_max = 255; + } + pci->cfg.bus_range->end = min_t(resource_size_t, pci->cfg.bus_range->end, bus_max); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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