Revision 61f01dd941ba9e06d2bf05994450ecc3d61b6b8b authored by Andy Lutomirski on 26 April 2015, 23:47:59 UTC, committed by Linus Torvalds on 27 April 2015, 00:57:38 UTC
AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with SS == 0 results in an invalid usermode state in which SS is apparently equal to __USER_DS but causes #SS if used. Work around the issue by setting SS to __KERNEL_DS __switch_to, thus ensuring that SYSRET never happens with SS set to NULL. This was exposed by a recent vDSO cleanup. Fixes: e7d6eefaaa44 x86/vdso32/syscall.S: Do not load __USER32_DS to %ss Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Peter Anvin <hpa@zytor.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Brian Gerst <brgerst@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 1190944
dma.c
/*
* Copyright (C) 2011 Texas Instruments Incorporated
* Author: Mark Salter <msalter@redhat.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/module.h>
#include <linux/dma-mapping.h>
#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/scatterlist.h>
#include <asm/cacheflush.h>
static void c6x_dma_sync(dma_addr_t handle, size_t size,
enum dma_data_direction dir)
{
unsigned long paddr = handle;
BUG_ON(!valid_dma_direction(dir));
switch (dir) {
case DMA_FROM_DEVICE:
L2_cache_block_invalidate(paddr, paddr + size);
break;
case DMA_TO_DEVICE:
L2_cache_block_writeback(paddr, paddr + size);
break;
case DMA_BIDIRECTIONAL:
L2_cache_block_writeback_invalidate(paddr, paddr + size);
break;
default:
break;
}
}
dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
enum dma_data_direction dir)
{
dma_addr_t addr = virt_to_phys(ptr);
c6x_dma_sync(addr, size, dir);
debug_dma_map_page(dev, virt_to_page(ptr),
(unsigned long)ptr & ~PAGE_MASK, size,
dir, addr, true);
return addr;
}
EXPORT_SYMBOL(dma_map_single);
void dma_unmap_single(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
c6x_dma_sync(handle, size, dir);
debug_dma_unmap_page(dev, handle, size, dir, true);
}
EXPORT_SYMBOL(dma_unmap_single);
int dma_map_sg(struct device *dev, struct scatterlist *sglist,
int nents, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;
for_each_sg(sglist, sg, nents, i)
sg->dma_address = dma_map_single(dev, sg_virt(sg), sg->length,
dir);
debug_dma_map_sg(dev, sglist, nents, nents, dir);
return nents;
}
EXPORT_SYMBOL(dma_map_sg);
void dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
int nents, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;
for_each_sg(sglist, sg, nents, i)
dma_unmap_single(dev, sg_dma_address(sg), sg->length, dir);
debug_dma_unmap_sg(dev, sglist, nents, dir);
}
EXPORT_SYMBOL(dma_unmap_sg);
void dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
c6x_dma_sync(handle, size, dir);
debug_dma_sync_single_for_cpu(dev, handle, size, dir);
}
EXPORT_SYMBOL(dma_sync_single_for_cpu);
void dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
c6x_dma_sync(handle, size, dir);
debug_dma_sync_single_for_device(dev, handle, size, dir);
}
EXPORT_SYMBOL(dma_sync_single_for_device);
void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sglist,
int nents, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;
for_each_sg(sglist, sg, nents, i)
dma_sync_single_for_cpu(dev, sg_dma_address(sg),
sg->length, dir);
debug_dma_sync_sg_for_cpu(dev, sglist, nents, dir);
}
EXPORT_SYMBOL(dma_sync_sg_for_cpu);
void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sglist,
int nents, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;
for_each_sg(sglist, sg, nents, i)
dma_sync_single_for_device(dev, sg_dma_address(sg),
sg->length, dir);
debug_dma_sync_sg_for_device(dev, sglist, nents, dir);
}
EXPORT_SYMBOL(dma_sync_sg_for_device);
/* Number of entries preallocated for DMA-API debugging */
#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
static int __init dma_init(void)
{
dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
return 0;
}
fs_initcall(dma_init);
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...