On Wed, Jan 28, 2015 at 5:05 AM, Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > On Tue, Jan 27, 2015 at 06:55:15PM +0000, Murali Karicheri wrote: >> On 01/27/2015 06:27 AM, Robin Murphy wrote: >> > On 23/01/15 22:32, Murali Karicheri wrote: >> >> Fix the dma-range size when the DT attribute is missing. i.e set size to >> >> dev->coherent_dma_mask + 1 instead of dev->coherent_dma_mask. To detect >> >> overflow when mask is set to max of u64, add a check, log error and >> >> return. >> >> Some platform use mask format for size in DTS. So add a work around to >> >> catch this and fix. >> >> >> >> Cc: Joerg Roedel <joro@xxxxxxxxxx> >> >> Cc: Grant Likely <grant.likely@xxxxxxxxxx> >> >> Cc: Rob Herring <robh+dt@xxxxxxxxxx> >> >> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >> >> Cc: Will Deacon <will.deacon@xxxxxxx> >> >> Cc: Russell King <linux@xxxxxxxxxxxxxxxx> >> >> Cc: Arnd Bergmann <arnd@xxxxxxxx> >> >> Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx> >> >> >> >> Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx> >> >> --- >> >> drivers/of/device.c | 14 +++++++++++++- >> >> 1 file changed, 13 insertions(+), 1 deletion(-) >> >> >> >> diff --git a/drivers/of/device.c b/drivers/of/device.c >> >> index 2de320d..0a5ff54 100644 >> >> --- a/drivers/of/device.c >> >> +++ b/drivers/of/device.c >> >> @@ -105,12 +105,24 @@ void of_dma_configure(struct device *dev, struct >> >> device_node *np) >> >> ret = of_dma_get_range(np, &dma_addr, &paddr, &size); >> >> if (ret < 0) { >> >> dma_addr = offset = 0; >> >> - size = dev->coherent_dma_mask; >> >> + size = dev->coherent_dma_mask + 1; >> >> } else { >> >> offset = PFN_DOWN(paddr - dma_addr); >> >> + /* >> >> + * Add a work around to treat the size as mask + 1 in case >> >> + * it is defined in DT as a mask. >> >> + */ >> >> + if (size & 1) >> >> + size = size + 1; >> >> dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); >> >> } >> >> >> >> + /* if size is 0, we have an overflow of u64 */ >> >> + if (!size) { >> >> + dev_err(dev, "invalid size\n"); >> >> + return; >> >> + } >> >> + >> > >> > This seems potentially fragile to dodgy DTs given that we might also be >> > using size to make a mask later. Would it make sense to double-up a >> > sanity check as mask-format detection? Something like: >> > >> > if is_power_of_2(size) >> > // use size >> > else if is_power_of_2(size + 1) >> > // use size + 1 >> > else >> > // cry >> >> How about having the logic like this? >> >> ret = of_dma_get_range(np, &dma_addr, &paddr, &size); >> if (ret < 0) { >> dma_addr = offset = 0; >> size = dev->coherent_dma_mask + 1; >> } else { >> offset = PFN_DOWN(paddr - dma_addr); >> dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); >> } >> >> if (is_power_of_2(size + 1)) >> size = size + 1; >> else if (!is_power_of_2(size)) >> { >> dev_err(dev, "invalid size\n"); >> return; >> } > > In of_dma_configure(), we currently assume that the default coherent > mask is 32-bit. In this thread: > > http://article.gmane.org/gmane.linux.kernel/1835096 > > we talked about setting the coherent mask based on size automatically. > I'm not sure about the size but I think we can assume is 32-bit mask + 1 > if it is not specified in the DT. Instead of just assuming a default > mask, let's assume a default size and create the mask based on this > (untested): > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c > index 5b33c6a21807..9ff8d1286b44 100644 > --- a/drivers/of/platform.c > +++ b/drivers/of/platform.c > @@ -170,10 +170,10 @@ static void of_dma_configure(struct device *dev) > struct iommu_ops *iommu; > > /* > - * Set default dma-mask to 32 bit. Drivers are expected to setup > - * the correct supported dma_mask. > + * Set default size to cover the 32-bit. Drivers are expected to setup > + * the correct size and dma_mask. > */ > - dev->coherent_dma_mask = DMA_BIT_MASK(32); > + size = 1ULL << 32; > > /* > * Set it to coherent_dma_mask by default if the architecture > @@ -185,13 +185,24 @@ static void of_dma_configure(struct device *dev) > ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size); > if (ret < 0) { > dma_addr = offset = 0; > - size = dev->coherent_dma_mask; Are we assuming dma_addr, paddr and size are not touched on error? If so, we can get rid of this clause entirely. > } else { > offset = PFN_DOWN(paddr - dma_addr); > dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset); > } > dev->dma_pfn_offset = offset; > > + /* > + * Workaround for DTs setting the size to a mask or 0. > + */ > + if (is_power_of_2(size + 1)) > + size += 1; As I mentioned, I think power of 2 is too restrictive (from a DT perspective even though the kernel may require a power of 2 here for the mask). Just checking bit0 set should be enough. Also, we need a WARN here so DTs get fixed. > + > + /* > + * Coherent DMA masks larger than 32-bit must be explicitly set by the > + * driver. > + */ > + dev->coherent_dma_mask = min(DMA_BIT_MASK(32), DMA_BIT_MASK(ilog2(size))); > + > coherent = of_dma_is_coherent(dev->of_node); > dev_dbg(dev, "device is%sdma coherent\n", > coherent ? " " : " not "); > > -- > Catalin -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html