Hi Andre, Jörg,
On Fri, Sep 18, 2015 at 11:09 AM, Andre Przywara <andre.przywara@xxxxxxx> wrote:
> Though iommu_tbl_range_alloc() is only used by Sparc code, the
> function itself lives in lib/iommu-common.c and is thus included in
> other architecture's code as well.
> When compiled on a 32-bit architecture using 64-bit DMA addresses
> (ARM with LPAE), there is a compiler warning about a type mismatch
> between dma_addr_t and the return type of this function:
>
> In file included from /src/linux/include/linux/dma-mapping.h:86:0,
> from /src/linux/lib/iommu-common.c:11:
> /src/linux/lib/iommu-common.c: In function 'iommu_tbl_range_alloc':
> /src/linux/arch/arm/include/asm/dma-mapping.h:16:24: warning: large integer implicitly truncated to unsigned type [-Woverflow]
> #define DMA_ERROR_CODE (~(dma_addr_t)0x0)
> ^
> /src/linux/lib/iommu-common.c:127:10: note: in expansion of macro
> 'DMA_ERROR_CODE'
> return DMA_ERROR_CODE;
While I welcome a fix for this annoying warning on arm...
> --- a/lib/iommu-common.c
> +++ b/lib/iommu-common.c
> @@ -99,15 +99,16 @@ void iommu_tbl_pool_init(struct iommu_map_table *iommu,
> }
> EXPORT_SYMBOL(iommu_tbl_pool_init);
>
> -unsigned long iommu_tbl_range_alloc(struct device *dev,
> - struct iommu_map_table *iommu,
> - unsigned long npages,
> - unsigned long *handle,
> - unsigned long mask,
> - unsigned int align_order)
> +dma_addr_t iommu_tbl_range_alloc(struct device *dev,
> + struct iommu_map_table *iommu,
> + unsigned long npages,
> + unsigned long *handle,
> + unsigned long mask,
> + unsigned int align_order)
> {
> unsigned int pool_hash = __this_cpu_read(iommu_hash_common);
> - unsigned long n, end, start, limit, boundary_size;
> + dma_addr_t n;
> + unsigned long end, start, limit, boundary_size;
... this doesn't look like the right fix.
Apparently 64-bit parisc doesn't set ARCH_DMA_ADDR_T_64BIT, hence assigning
(64-bit) "unsigned long" to (32-bit) dma_addr_t will truncate the address.
Does this function really need to return DMA_ERROR_CODE in case of
failure?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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