88 lines
3.5 KiB
Diff
88 lines
3.5 KiB
Diff
From 00135c26c13feaa5b906049483742a2249276416 Mon Sep 17 00:00:00 2001
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Message-Id: <00135c26c13feaa5b906049483742a2249276416.1522795098.git.Jim.Somerville@windriver.com>
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In-Reply-To: <21c11de06542297206c798b405b54a3ec9052aa4.1522795097.git.Jim.Somerville@windriver.com>
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References: <21c11de06542297206c798b405b54a3ec9052aa4.1522795097.git.Jim.Somerville@windriver.com>
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From: Akinobu Mita <akinobu.mita@gmail.com>
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Date: Wed, 4 Jun 2014 16:06:48 -0700
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Subject: [PATCH 17/33] x86: make dma_alloc_coherent() return zeroed memory if
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CMA is enabled
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This patchset enhances the DMA Contiguous Memory Allocator on x86.
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Currently the DMA CMA is only supported with pci-nommu dma_map_ops and
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furthermore it can't be enabled on x86_64. But I would like to allocate
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big contiguous memory with dma_alloc_coherent() and tell it to the device
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that requires it, regardless of which dma mapping implementation is
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actually used in the system.
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So this makes it work with swiotlb and intel-iommu dma_map_ops, too. And
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this also extends "cma=" kernel parameter to specify placement constraint
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by the physical address range of memory allocations. For example, CMA
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allocates memory below 4GB by "cma=64M@0-4G", it is required for the
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devices only supporting 32-bit addressing on 64-bit systems without iommu.
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This patch (of 5):
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Calling dma_alloc_coherent() with __GFP_ZERO must return zeroed memory.
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But when the contiguous memory allocator (CMA) is enabled on x86 and the
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memory region is allocated by dma_alloc_from_contiguous(), it doesn't
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return zeroed memory. Because dma_generic_alloc_coherent() forgot to fill
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the memory region with zero if it was allocated by
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dma_alloc_from_contiguous()
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Most implementations of dma_alloc_coherent() return zeroed memory
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regardless of whether __GFP_ZERO is specified. So this fixes it by
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unconditionally zeroing the allocated memory region.
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Alternatively, we could fix dma_alloc_from_contiguous() to return zeroed
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out memory and remove memset() from all caller of it. But we can't simply
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remove the memset on arm because __dma_clear_buffer() is used there for
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ensuring cache flushing and it is used in many places. Of course we can
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do redundant memset in dma_alloc_from_contiguous(), but I think this patch
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is less impact for fixing this problem.
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Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
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Cc: Marek Szyprowski <m.szyprowski@samsung.com>
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Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Cc: David Woodhouse <dwmw2@infradead.org>
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Cc: Don Dutile <ddutile@redhat.com>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Cc: Ingo Molnar <mingo@redhat.com>
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Cc: "H. Peter Anvin" <hpa@zytor.com>
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Cc: Andi Kleen <andi@firstfloor.org>
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Cc: Yinghai Lu <yinghai@kernel.org>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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(cherry picked from commit d92ef66c4f8fdf7a24736b1ab6c48d32de9bfc07)
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Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
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---
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arch/x86/kernel/pci-dma.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
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index 872079a..9d92ea8 100644
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--- a/arch/x86/kernel/pci-dma.c
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+++ b/arch/x86/kernel/pci-dma.c
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@@ -97,7 +97,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
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dma_mask = dma_alloc_coherent_mask(dev, flag);
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- flag |= __GFP_ZERO;
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+ flag &= ~__GFP_ZERO;
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again:
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page = NULL;
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if (!(flag & GFP_ATOMIC))
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@@ -118,7 +118,7 @@ again:
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return NULL;
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}
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-
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+ memset(page_address(page), 0, size);
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*dma_addr = addr;
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return page_address(page);
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}
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--
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1.8.3.1
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