linux_dsm_epyc7002/arch/arc/mm/dma.c
Christoph Hellwig 518a2f1925 dma-mapping: zero memory returned from dma_alloc_*
If we want to map memory from the DMA allocator to userspace it must be
zeroed at allocation time to prevent stale data leaks.   We already do
this on most common architectures, but some architectures don't do this
yet, fix them up, either by passing GFP_ZERO when we use the normal page
allocator or doing a manual memset otherwise.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Acked-by: Sam Ravnborg <sam@ravnborg.org> [sparc]
2018-12-20 08:13:52 +01:00

167 lines
4.4 KiB
C

/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/dma-noncoherent.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
/*
* ARCH specific callbacks for generic noncoherent DMA ops (dma/noncoherent.c)
* - hardware IOC not available (or "dma-coherent" not set for device in DT)
* - But still handle both coherent and non-coherent requests from caller
*
* For DMA coherent hardware (IOC) generic code suffices
*/
void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs)
{
unsigned long order = get_order(size);
struct page *page;
phys_addr_t paddr;
void *kvaddr;
bool need_coh = !(attrs & DMA_ATTR_NON_CONSISTENT);
/*
* __GFP_HIGHMEM flag is cleared by upper layer functions
* (in include/linux/dma-mapping.h) so we should never get a
* __GFP_HIGHMEM here.
*/
BUG_ON(gfp & __GFP_HIGHMEM);
page = alloc_pages(gfp | __GFP_ZERO, order);
if (!page)
return NULL;
/* This is linear addr (0x8000_0000 based) */
paddr = page_to_phys(page);
*dma_handle = paddr;
/*
* A coherent buffer needs MMU mapping to enforce non-cachability.
* kvaddr is kernel Virtual address (0x7000_0000 based).
*/
if (need_coh) {
kvaddr = ioremap_nocache(paddr, size);
if (kvaddr == NULL) {
__free_pages(page, order);
return NULL;
}
} else {
kvaddr = (void *)(u32)paddr;
}
/*
* Evict any existing L1 and/or L2 lines for the backing page
* in case it was used earlier as a normal "cached" page.
* Yeah this bit us - STAR 9000898266
*
* Although core does call flush_cache_vmap(), it gets kvaddr hence
* can't be used to efficiently flush L1 and/or L2 which need paddr
* Currently flush_cache_vmap nukes the L1 cache completely which
* will be optimized as a separate commit
*/
if (need_coh)
dma_cache_wback_inv(paddr, size);
return kvaddr;
}
void arch_dma_free(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle, unsigned long attrs)
{
phys_addr_t paddr = dma_handle;
struct page *page = virt_to_page(paddr);
if (!(attrs & DMA_ATTR_NON_CONSISTENT))
iounmap((void __force __iomem *)vaddr);
__free_pages(page, get_order(size));
}
long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
dma_addr_t dma_addr)
{
return __phys_to_pfn(dma_addr);
}
/*
* Cache operations depending on function and direction argument, inspired by
* https://lkml.org/lkml/2018/5/18/979
* "dma_sync_*_for_cpu and direction=TO_DEVICE (was Re: [PATCH 02/20]
* dma-mapping: provide a generic dma-noncoherent implementation)"
*
* | map == for_device | unmap == for_cpu
* |----------------------------------------------------------------
* TO_DEV | writeback writeback | none none
* FROM_DEV | invalidate invalidate | invalidate* invalidate*
* BIDIR | writeback+inv writeback+inv | invalidate invalidate
*
* [*] needed for CPU speculative prefetches
*
* NOTE: we don't check the validity of direction argument as it is done in
* upper layer functions (in include/linux/dma-mapping.h)
*/
void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
size_t size, enum dma_data_direction dir)
{
switch (dir) {
case DMA_TO_DEVICE:
dma_cache_wback(paddr, size);
break;
case DMA_FROM_DEVICE:
dma_cache_inv(paddr, size);
break;
case DMA_BIDIRECTIONAL:
dma_cache_wback_inv(paddr, size);
break;
default:
break;
}
}
void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
size_t size, enum dma_data_direction dir)
{
switch (dir) {
case DMA_TO_DEVICE:
break;
/* FROM_DEVICE invalidate needed if speculative CPU prefetch only */
case DMA_FROM_DEVICE:
case DMA_BIDIRECTIONAL:
dma_cache_inv(paddr, size);
break;
default:
break;
}
}
/*
* Plug in direct dma map ops.
*/
void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
const struct iommu_ops *iommu, bool coherent)
{
/*
* IOC hardware snoops all DMA traffic keeping the caches consistent
* with memory - eliding need for any explicit cache maintenance of
* DMA buffers.
*/
if (is_isa_arcv2() && ioc_enable && coherent)
dev->dma_coherent = true;
dev_info(dev, "use %sncoherent DMA ops\n",
dev->dma_coherent ? "" : "non");
}