Messages in this thread Patch in this message | | | From | David Daney <> | Subject | [PATCH v3 4/6] PCI: generic: Correct, and avoid overflow, in bus_max calculation. | Date | Tue, 22 Sep 2015 16:49:15 -0700 |
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From: David Daney <david.daney@cavium.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@cavium.com> --- No change from v2. Change from v1: Added text to host-generic-pci.txt
Documentation/devicetree/bindings/pci/host-generic-pci.txt | 4 +++- drivers/pci/host/pci-host-generic.c | 7 ++++--- 2 files changed, 7 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..105a968 100644 --- a/Documentation/devicetree/bindings/pci/host-generic-pci.txt +++ b/Documentation/devicetree/bindings/pci/host-generic-pci.txt @@ -34,7 +34,9 @@ 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. Properties of the /chosen node: diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c index 77cf4bd..0a9c453 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 +177,9 @@ 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) + bus_max = 255; pci->cfg.bus_range->end = min_t(resource_size_t, pci->cfg.bus_range->end, bus_max); -- 1.9.1
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