On Wed, Nov 19, 2014 at 1:22 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> I propose the following third alternative, which always computes full
> 64-bit base/limit, then casts them to the dma_addr_t size and compares to
> see if anything got chopped off.
>
> This is on top of pci/for-linus. Whatever we settle on, I'll fold it into
> the original patch before asking Linus to pull it.
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 1c5b1ca53bcd..c8ca98c2b480 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -407,6 +407,7 @@ static void pci_read_bridge_mmio_pref(struct pci_bus *child)
> {
> struct pci_dev *dev = child->self;
> u16 mem_base_lo, mem_limit_lo;
> + u64 base64, limit64;
> dma_addr_t base, limit;
> struct pci_bus_region region;
> struct resource *res;
> @@ -414,8 +415,8 @@ static void pci_read_bridge_mmio_pref(struct pci_bus *child)
> res = child->resource[2];
> pci_read_config_word(dev, PCI_PREF_MEMORY_BASE, &mem_base_lo);
> pci_read_config_word(dev, PCI_PREF_MEMORY_LIMIT, &mem_limit_lo);
> - base = ((dma_addr_t) mem_base_lo & PCI_PREF_RANGE_MASK) << 16;
> - limit = ((dma_addr_t) mem_limit_lo & PCI_PREF_RANGE_MASK) << 16;
> + base64 = (mem_base_lo & PCI_PREF_RANGE_MASK) << 16;
> + limit64 = (mem_limit_lo & PCI_PREF_RANGE_MASK) << 16;
>
> if ((mem_base_lo & PCI_PREF_RANGE_TYPE_MASK) == PCI_PREF_RANGE_TYPE_64) {
> u32 mem_base_hi, mem_limit_hi;
> @@ -429,17 +430,20 @@ static void pci_read_bridge_mmio_pref(struct pci_bus *child)
> * this, just assume they are not being used.
> */
> if (mem_base_hi <= mem_limit_hi) {
> - if (sizeof(dma_addr_t) < 8) {
> - if (mem_base_hi || mem_limit_hi) {
> - dev_err(&dev->dev, "can't handle 64-bit address space for bridge\n");
> - return;
> - }
> - } else {
> - base |= ((dma_addr_t) mem_base_hi) << 32;
> - limit |= ((dma_addr_t) mem_limit_hi) << 32;
> - }
> + base64 |= (u64) mem_base_hi << 32;
> + limit64 |= (u64) mem_limit_hi << 32;
> }
> }
> +
> + base = (dma_addr_t) base64;
> + limit = (dma_addr_t) limit64;
> +
> + if (base != base64) {
> + dev_err(&dev->dev, "can't handle bridge window above 4GB (bus address %#010llx)\n",
> + (unsigned long long) base64);
> + return;
> + }
> +
Yes, that is better. on 64bit, compiler will omit last 7 lines for comparing...
Thanks
Yinghai
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