Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755785Ab3HEWnt (ORCPT ); Mon, 5 Aug 2013 18:43:49 -0400 Received: from mail-qa0-f47.google.com ([209.85.216.47]:34189 "EHLO mail-qa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754946Ab3HEWns (ORCPT ); Mon, 5 Aug 2013 18:43:48 -0400 MIME-Version: 1.0 In-Reply-To: References: <20130801213420.GL23006@n2100.arm.linux.org.uk> Date: Mon, 5 Aug 2013 17:43:47 -0500 Message-ID: Subject: Re: [PATCH RFC 46/51] ARM: DMA-API: better handing of DMA masks for coherent allocations From: Rob Herring To: Russell King Cc: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Arnd Bergmann Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6674 Lines: 169 On Thu, Aug 1, 2013 at 5:20 PM, Russell King wrote: > We need to start treating DMA masks as something which is specific to > the bus that the device resides on, otherwise we're going to hit all > sorts of nasty issues with LPAE and 32-bit DMA controllers in >32-bit > systems, where memory is offset from PFN 0. > > In order to start doing this, we convert the DMA mask to a PFN using > the device specific dma_to_pfn() macro. This is the reverse of the > pfn_to_dma() macro which is used to get the DMA address for the device. > > This gives us a PFN mask, which we can then check against the PFN > limit of the DMA zone. > > Signed-off-by: Russell King > --- > arch/arm/mm/dma-mapping.c | 49 ++++++++++++++++++++++++++++++++++++++++---- > arch/arm/mm/init.c | 2 + > arch/arm/mm/mm.h | 2 + > 3 files changed, 48 insertions(+), 5 deletions(-) I believe you missed handling __dma_alloc. I have a different fix than what Andreas posted. I think DMA zone handling is broken in all cases here. Feel free to combine this in to your patch if you agree. Author: Rob Herring Date: Thu Aug 1 15:51:17 2013 -0500 ARM: fix dma-mapping on LPAE With LPAE, the DMA zone size may be 4GB, so the GFP_DMA flag needs to be set when the mask is less than or equal to the arm_dma_limit. This also fixes a bug with DMA zone mask handling. GFP_DMA should be set for any mask less than or equal to arm_dma_limit, not just less than ~0UL. Signed-off-by: Rob Herring diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 7f9b179..3d9bdfb 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -651,7 +651,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, if (!mask) return NULL; - if (mask < 0xffffffffULL) + if (mask <= (u64)arm_dma_limit) gfp |= GFP_DMA; /* > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 7f9b179..ef0efab 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -173,10 +173,30 @@ static u64 get_coherent_dma_mask(struct device *dev) > return 0; > } > > - if ((~mask) & (u64)arm_dma_limit) { > - dev_warn(dev, "coherent DMA mask %#llx is smaller " > - "than system GFP_DMA mask %#llx\n", > - mask, (u64)arm_dma_limit); > + /* > + * If the mask allows for more memory than we can address, > + * and we actually have that much memory, then fail the > + * allocation. > + */ > + if (sizeof(mask) != sizeof(dma_addr_t) && > + mask > (dma_addr_t)~0 && > + dma_to_pfn(dev, ~0) > arm_dma_pfn_limit) { > + dev_warn(dev, "Coherent DMA mask %#llx is larger than dma_addr_t allows\n", > + mask); > + dev_warn(dev, "Driver did not use or check the return value from dma_set_coherent_mask()?\n"); > + return 0; > + } > + > + /* > + * Now check that the mask, when translated to a PFN, > + * fits within the allowable addresses which we can > + * allocate. > + */ > + if (dma_to_pfn(dev, mask) < arm_dma_pfn_limit) { > + dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n", > + mask, > + dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1, > + arm_dma_pfn_limit + 1); > return 0; > } > } > @@ -1008,8 +1028,27 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, > */ > int dma_supported(struct device *dev, u64 mask) > { > - if (mask < (u64)arm_dma_limit) > + unsigned long limit; > + > + /* > + * If the mask allows for more memory than we can address, > + * and we actually have that much memory, then we must > + * indicate that DMA to this device is not supported. > + */ > + if (sizeof(mask) != sizeof(dma_addr_t) && > + mask > (dma_addr_t)~0 && > + dma_to_pfn(dev, ~0) > arm_dma_pfn_limit) > + return 0; > + > + /* > + * Translate the device's DMA mask to a PFN limit. This > + * PFN number includes the page which we can DMA to. > + */ > + limit = dma_to_pfn(dev, mask); > + > + if (limit < arm_dma_pfn_limit) > return 0; > + > return 1; > } > EXPORT_SYMBOL(dma_supported); > diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c > index 15225d8..b5b5836 100644 > --- a/arch/arm/mm/init.c > +++ b/arch/arm/mm/init.c > @@ -217,6 +217,7 @@ EXPORT_SYMBOL(arm_dma_zone_size); > * so a successful GFP_DMA allocation will always satisfy this. > */ > phys_addr_t arm_dma_limit; > +unsigned long arm_dma_pfn_limit; > > static void __init arm_adjust_dma_zone(unsigned long *size, unsigned long *hole, > unsigned long dma_size) > @@ -239,6 +240,7 @@ void __init setup_dma_zone(struct machine_desc *mdesc) > arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1; > } else > arm_dma_limit = 0xffffffff; > + arm_dma_pfn_limit = arm_dma_limit >> PAGE_SHIFT; > #endif > } > > diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h > index d5a4e9a..d5a982d 100644 > --- a/arch/arm/mm/mm.h > +++ b/arch/arm/mm/mm.h > @@ -81,8 +81,10 @@ extern __init void add_static_vm_early(struct static_vm *svm); > > #ifdef CONFIG_ZONE_DMA > extern phys_addr_t arm_dma_limit; > +extern unsigned long arm_dma_pfn_limit; > #else > #define arm_dma_limit ((phys_addr_t)~0) > +#define arm_dma_pfn_limit (~0ul >> PAGE_SHIFT) > #endif > > extern phys_addr_t arm_lowmem_limit; > -- > 1.7.4.4 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/