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msm: kgsl: Map a guard page on the back of GPU MMU regions

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Add a guard page on the backside of page_alloc MMU mappings to protect
against an over zealous GPU pre-fetch engine that sometimes oversteps the
end of the mapped region. The same phsyical page can be re-used for each
mapping so we only need to allocate one phsyical page to rule them all
and in the darkness bind them.
This commit is contained in:
securecrt 2012-07-26 14:04:25 +08:00
parent 4822aef009
commit 394bda433a
2 changed files with 53 additions and 6 deletions
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3
drivers/gpu/msm/kgsl.h
View File

@ -118,6 +118,8 @@ struct kgsl_memdesc_ops {
int (*map_kernel_mem)(struct kgsl_memdesc *);
};
#define KGSL_MEMDESC_GUARD_PAGE BIT(0)
/* shared memory allocation */
struct kgsl_memdesc {
struct kgsl_pagetable *pagetable;
@ -129,6 +131,7 @@ struct kgsl_memdesc {
struct scatterlist *sg;
unsigned int sglen;
struct kgsl_memdesc_ops *ops;
int flags;
};
/* List of different memory entry types */

56
drivers/gpu/msm/kgsl_sharedmem.c
View File

@ -64,6 +64,13 @@ struct mem_entry_stats {
}
/*
* One page allocation for a guard region to protect against over-zealous
* GPU pre-fetch
*/
static struct page *kgsl_guard_page;
/**
* Given a kobj, find the process structure attached to it
*/
@ -334,13 +341,20 @@ static void kgsl_page_alloc_free(struct kgsl_memdesc *memdesc)
{
int i = 0;
struct scatterlist *sg;
int sglen = memdesc->sglen;
/* Don't free the guard page if it was used */
if (memdesc->flags & KGSL_MEMDESC_GUARD_PAGE)
sglen--;
kgsl_driver.stats.page_alloc -= memdesc->size;
if (memdesc->hostptr) {
vunmap(memdesc->hostptr);
kgsl_driver.stats.vmalloc -= memdesc->size;
}
if (memdesc->sg)
for_each_sg(memdesc->sg, sg, memdesc->sglen, i)
for_each_sg(memdesc->sg, sg, sglen, i)
__free_page(sg_page(sg));
}
@ -363,17 +377,23 @@ static int kgsl_page_alloc_map_kernel(struct kgsl_memdesc *memdesc)
pgprot_t page_prot = pgprot_writecombine(PAGE_KERNEL);
struct page **pages = NULL;
struct scatterlist *sg;
int sglen = memdesc->sglen;
int i;
/* Don't map the guard page if it exists */
if (memdesc->flags & KGSL_MEMDESC_GUARD_PAGE)
sglen--;
/* create a list of pages to call vmap */
pages = vmalloc(memdesc->sglen * sizeof(struct page *));
pages = vmalloc(sglen * sizeof(struct page *));
if (!pages) {
KGSL_CORE_ERR("vmalloc(%d) failed\n",
memdesc->sglen * sizeof(struct page *));
sglen * sizeof(struct page *));
return -ENOMEM;
}
for_each_sg(memdesc->sg, sg, memdesc->sglen, i)
for_each_sg(memdesc->sg, sg, sglen, i)
pages[i] = sg_page(sg);
memdesc->hostptr = vmap(pages, memdesc->sglen,
memdesc->hostptr = vmap(pages, sglen,
VM_IOREMAP, page_prot);
KGSL_STATS_ADD(memdesc->size, kgsl_driver.stats.vmalloc,
kgsl_driver.stats.vmalloc_max);
@ -472,6 +492,14 @@ _kgsl_sharedmem_page_alloc(struct kgsl_memdesc *memdesc,
int sglen = PAGE_ALIGN(size) / PAGE_SIZE;
int i;
/*
* Add guard page to the end of the allocation when the
* IOMMU is in use.
*/
if (kgsl_mmu_get_mmutype() == KGSL_MMU_TYPE_IOMMU)
sglen++;
memdesc->size = size;
memdesc->pagetable = pagetable;
memdesc->priv = KGSL_MEMFLAGS_CACHED;
@ -491,7 +519,7 @@ _kgsl_sharedmem_page_alloc(struct kgsl_memdesc *memdesc,
memdesc->sglen = sglen;
sg_init_table(memdesc->sg, sglen);
for (i = 0; i < memdesc->sglen; i++) {
for (i = 0; i < PAGE_ALIGN(size) / PAGE_SIZE; i++) {
struct page *page = alloc_page(GFP_KERNEL | __GFP_ZERO |
__GFP_HIGHMEM);
if (!page) {
@ -502,6 +530,22 @@ _kgsl_sharedmem_page_alloc(struct kgsl_memdesc *memdesc,
flush_dcache_page(page);
sg_set_page(&memdesc->sg[i], page, PAGE_SIZE, 0);
}
/* ADd the guard page to the end of the sglist */
if (kgsl_mmu_get_mmutype() == KGSL_MMU_TYPE_IOMMU) {
if (kgsl_guard_page == NULL)
kgsl_guard_page = alloc_page(GFP_KERNEL | __GFP_ZERO |
__GFP_HIGHMEM);
if (kgsl_guard_page != NULL) {
sg_set_page(&memdesc->sg[sglen - 1], kgsl_guard_page,
PAGE_SIZE, 0);
memdesc->flags |= KGSL_MEMDESC_GUARD_PAGE;
} else
memdesc->sglen--;
}
outer_cache_range_op_sg(memdesc->sg, memdesc->sglen,
KGSL_CACHE_OP_FLUSH);