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Revert "ARM: 7169/1: topdown mmap support"

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commit 7dbaa46678
(ARM: 7169/1: topdown mmap support) allocates mmap addresses from
the top addresses instead of the bottom. Unfortunately, some
userspace components are broken and do checks such as the following:

void* addr = mmap(...);
// Top bit is now the sign bit...
int test = (int)addr;
if (test < 0) {
	//failure
}

Which means that any address greater than 0x80000000 will be marked
as a failure. Until we verify all userspace components are fixed,
revert this change.

Change-Id: I2eacbfb4f7b8fc9bf5704ca90d31c409819d7fbe
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
This commit is contained in:
Laura Abbott 2012-08-15 10:01:48 -07:00 committed by Stephen Boyd
parent f673029440
commit ce95e6e6ce
3 changed files with 5 additions and 171 deletions
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1
arch/arm/include/asm/pgtable.h
View file

@ -313,7 +313,6 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
* We provide our own arch_get_unmapped_area to cope with VIPT caches.
*/
#define HAVE_ARCH_UNMAPPED_AREA
#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
/*
* remap a physical page `pfn' of size `size' with page protection `prot'

2
arch/arm/include/asm/processor.h
View file

@ -126,8 +126,6 @@ static inline void prefetch(const void *ptr)
#endif
#define HAVE_ARCH_PICK_MMAP_LAYOUT
#endif
#endif /* __ASM_ARM_PROCESSOR_H */

173
arch/arm/mm/mmap.c
View file

@ -11,49 +11,10 @@
#include <linux/random.h>
#include <asm/cachetype.h>
static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
unsigned long pgoff)
{
unsigned long base = addr & ~(SHMLBA-1);
unsigned long off = (pgoff << PAGE_SHIFT) & (SHMLBA-1);
if (base + off <= addr)
return base + off;
return base - off;
}
#define COLOUR_ALIGN(addr,pgoff) \
((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
(((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
/* gap between mmap and stack */
#define MIN_GAP (128*1024*1024UL)
#define MAX_GAP ((TASK_SIZE)/6*5)
static int mmap_is_legacy(void)
{
if (current->personality & ADDR_COMPAT_LAYOUT)
return 1;
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
return 1;
return sysctl_legacy_va_layout;
}
static unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
if (gap < MIN_GAP)
gap = MIN_GAP;
else if (gap > MAX_GAP)
gap = MAX_GAP;
return PAGE_ALIGN(TASK_SIZE - gap - rnd);
}
/*
* We need to ensure that shared mappings are correctly aligned to
* avoid aliasing issues with VIPT caches. We need to ensure that
@ -107,9 +68,13 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
if (len > mm->cached_hole_size) {
start_addr = addr = mm->free_area_cache;
} else {
start_addr = addr = mm->mmap_base;
start_addr = addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
}
/* 8 bits of randomness in 20 address space bits */
if ((current->flags & PF_RANDOMIZE) &&
!(current->personality & ADDR_NO_RANDOMIZE))
addr += (get_random_int() % (1 << 8)) << PAGE_SHIFT;
full_search:
if (do_align)
@ -146,134 +111,6 @@ full_search:
}
}
unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
int do_align = 0;
int aliasing = cache_is_vipt_aliasing();
/*
* We only need to do colour alignment if either the I or D
* caches alias.
*/
if (aliasing)
do_align = filp || (flags & MAP_SHARED);
/* requested length too big for entire address space */
if (len > TASK_SIZE)
return -ENOMEM;
if (flags & MAP_FIXED) {
if (aliasing && flags & MAP_SHARED &&
(addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
return -EINVAL;
return addr;
}
/* requesting a specific address */
if (addr) {
if (do_align)
addr = COLOUR_ALIGN(addr, pgoff);
else
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
/* check if free_area_cache is useful for us */
if (len <= mm->cached_hole_size) {
mm->cached_hole_size = 0;
mm->free_area_cache = mm->mmap_base;
}
/* either no address requested or can't fit in requested address hole */
addr = mm->free_area_cache;
if (do_align) {
unsigned long base = COLOUR_ALIGN_DOWN(addr - len, pgoff);
addr = base + len;
}
/* make sure it can fit in the remaining address space */
if (addr > len) {
vma = find_vma(mm, addr-len);
if (!vma || addr <= vma->vm_start)
/* remember the address as a hint for next time */
return (mm->free_area_cache = addr-len);
}
if (mm->mmap_base < len)
goto bottomup;
addr = mm->mmap_base - len;
if (do_align)
addr = COLOUR_ALIGN_DOWN(addr, pgoff);
do {
/*
* Lookup failure means no vma is above this address,
* else if new region fits below vma->vm_start,
* return with success:
*/
vma = find_vma(mm, addr);
if (!vma || addr+len <= vma->vm_start)
/* remember the address as a hint for next time */
return (mm->free_area_cache = addr);
/* remember the largest hole we saw so far */
if (addr + mm->cached_hole_size < vma->vm_start)
mm->cached_hole_size = vma->vm_start - addr;
/* try just below the current vma->vm_start */
addr = vma->vm_start - len;
if (do_align)
addr = COLOUR_ALIGN_DOWN(addr, pgoff);
} while (len < vma->vm_start);
bottomup:
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
mm->cached_hole_size = ~0UL;
mm->free_area_cache = TASK_UNMAPPED_BASE;
addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
/*
* Restore the topdown base:
*/
mm->free_area_cache = mm->mmap_base;
mm->cached_hole_size = ~0UL;
return addr;
}
void arch_pick_mmap_layout(struct mm_struct *mm)
{
unsigned long random_factor = 0UL;
/* 8 bits of randomness in 20 address space bits */
if ((current->flags & PF_RANDOMIZE) &&
!(current->personality & ADDR_NO_RANDOMIZE))
random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT;
if (mmap_is_legacy()) {
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
mm->get_unmapped_area = arch_get_unmapped_area;
mm->unmap_area = arch_unmap_area;
} else {
mm->mmap_base = mmap_base(random_factor);
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
mm->unmap_area = arch_unmap_area_topdown;
}
}
/*
* You really shouldn't be using read() or write() on /dev/mem. This