- 根目录:
- arch
- powerpc
- mm
- slice.c
/*
* address space "slices" (meta-segments) support
*
* Copyright (C) 2007 Benjamin Herrenschmidt, IBM Corporation.
*
* Based on hugetlb implementation
*
* Copyright (C) 2003 David Gibson, IBM Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#undef DEBUG
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <asm/mman.h>
#include <asm/mmu.h>
#include <asm/spu.h>
/* some sanity checks */
#if (PGTABLE_RANGE >> 43) > SLICE_MASK_SIZE
#error PGTABLE_RANGE exceeds slice_mask high_slices size
#endif
static DEFINE_SPINLOCK(slice_convert_lock);
#ifdef DEBUG
int _slice_debug = 1;
static void slice_print_mask(const char *label, struct slice_mask mask)
{
char *p, buf[16 + 3 + 64 + 1];
int i;
if (!_slice_debug)
return;
p = buf;
for (i = 0; i < SLICE_NUM_LOW; i++)
*(p++) = (mask.low_slices & (1 << i)) ? '1' : '0';
*(p++) = ' ';
*(p++) = '-';
*(p++) = ' ';
for (i = 0; i < SLICE_NUM_HIGH; i++)
*(p++) = (mask.high_slices & (1ul << i)) ? '1' : '0';
*(p++) = 0;
printk(KERN_DEBUG "%s:%s\n", label, buf);
}
#define slice_dbg(fmt...) do { if (_slice_debug) pr_debug(fmt); } while(0)
#else
static void slice_print_mask(const char *label, struct slice_mask mask) {}
#define slice_dbg(fmt...)
#endif
static struct slice_mask slice_range_to_mask(unsigned long start,
unsigned long len)
{
unsigned long end = start + len - 1;
struct slice_mask ret = { 0, 0 };
if (start < SLICE_LOW_TOP) {
unsigned long mend = min(end, SLICE_LOW_TOP);
unsigned long mstart = min(start, SLICE_LOW_TOP);
ret.low_slices = (1u << (GET_LOW_SLICE_INDEX(mend) + 1))
- (1u << GET_LOW_SLICE_INDEX(mstart));
}
if ((start + len) > SLICE_LOW_TOP)
ret.high_slices = (1ul << (GET_HIGH_SLICE_INDEX(end) + 1))
- (1ul << GET_HIGH_SLICE_INDEX(start));
return ret;
}
static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
unsigned long len)
{
struct vm_area_struct *vma;
if ((mm->task_size - len) < addr)
return 0;
vma = find_vma(mm, addr);
return (!vma || (addr + len) <= vma->vm_start);
}
static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
{
return !slice_area_is_free(mm, slice << SLICE_LOW_SHIFT,
1ul << SLICE_LOW_SHIFT);
}
static int slice_high_has_vma(struct mm_struct *mm, unsigned long slice)
{
unsigned long start = slice << SLICE_HIGH_SHIFT;
unsigned long end = start + (1ul << SLICE_HIGH_SHIFT);
/* Hack, so that each addresses is controlled by exactly one
* of the high or low area bitmaps, the first high area starts
* at 4GB, not 0 */
if (start == 0)
start = SLICE_LOW_TOP;
return !slice_area_is_free(mm, start, end - start);
}
static struct slice_mask slice_mask_for_free(struct mm_struct *mm)
{
struct slice_mask ret = { 0, 0 };
unsigned long i;
for (i = 0; i < SLICE_NUM_LOW; i++)
if (!slice_low_has_vma(mm, i))
ret.low_slices |= 1u << i;
if (mm->task_size <= SLICE_LOW_TOP)
return ret;
for (i = 0; i < SLICE_NUM_HIGH; i++)
if (!slice_high_has_vma(mm, i))
ret.high_slices |= 1ul << i;
return ret;
}
static struct slice_mask slice_mask_for_size(struct mm_struct *mm, int psize)
{
unsigned char *hpsizes;
int index, mask_index;
struct slice_mask ret = { 0, 0 };
unsigned long i;
u64 lpsizes;
lpsizes = mm->context.low_slices_psize;
for (i = 0; i < SLICE_NUM_LOW; i++)
if (((lpsizes >> (i * 4)) & 0xf) == psize)
ret.low_slices |= 1u << i;
hpsizes = mm->context.high_slices_psize;
for (i = 0; i < SLICE_NUM_HIGH; i++) {
mask_index = i & 0x1;
index = i >> 1;
if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == psize)
ret.high_slices |= 1ul << i;
}
return ret;
}
static int slice_check_fit(struct slice_mask mask, struct slice_mask available)
{
return (mask.low_slices & available.low_slices) == mask.low_slices &&
(mask.high_slices & available.high_slices) == mask.high_slices;
}
static void slice_flush_segments(void *parm)
{
struct mm_struct *mm = parm;
unsigned long flags;
if (mm != current->active_mm)
return;
/* update the paca copy of the context struct */
get_paca()->context = current->active_mm->context;
local_irq_save(flags);
slb_flush_and_rebolt();
local_irq_restore(flags);
}
static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psize)
{
int index, mask_index;
/* Write the new slice psize bits */
unsigned char *hpsizes;
u64 lpsizes;
unsigned long i, flags;
slice_dbg("slice_convert(mm=%p, psize=%d)\n", mm, psize);
slice_print_mask(" mask", mask);
/* We need to use a spinlock here to protect against
* concurrent 64k -> 4k demotion ...
*/
spin_lock_irqsave(&slice_convert_lock, flags);
lpsizes = mm->context.low_slices_psize;
for (i = 0; i < SLICE_NUM_LOW; i++)
if (mask.low_slices & (1u << i))
lpsizes = (lpsizes & ~(0xful << (i * 4))) |
(((unsigned long)psize) << (i * 4));
/* Assign the value back */
mm->context.low_slices_psize = lpsizes;
hpsizes = mm->context.high_slices_psize;
for (i = 0; i < SLICE_NUM_HIGH; i++) {
mask_index = i & 0x1;
index = i >> 1;
if (mask.high_slices & (1ul << i))
hpsizes[index] = (hpsizes[index] &
~(0xf << (mask_index * 4))) |
(((unsigned long)psize) << (mask_index * 4));
}
slice_dbg(" lsps=%lx, hsps=%lx\n",
mm->context.low_slices_psize,
mm->context.high_slices_psize);
spin_unlock_irqrestore(&slice_convert_lock, flags);
#ifdef CONFIG_SPU_BASE
spu_flush_all_slbs(mm);
#endif
}
/*
* Compute which slice addr is part of;
* set *boundary_addr to the start or end boundary of that slice
* (depending on 'end' parameter);
* return boolean indicating if the slice is marked as available in the
* 'available' slice_mark.
*/
static bool slice_scan_available(unsigned long addr,
struct slice_mask available,
int end,
unsigned long *boundary_addr)
{
unsigned long slice;
if (addr < SLICE_LOW_TOP) {
slice = GET_LOW_SLICE_INDEX(addr);
*boundary_addr = (slice + end) << SLICE_LOW_SHIFT;
return !!(available.low_slices & (1u << slice));
} else {
slice = GET_HIGH_SLICE_INDEX(addr);
*boundary_addr = (slice + end) ?
((slice + end) << SLICE_HIGH_SHIFT) : SLICE_LOW_TOP;
return !!(available.high_slices & (1u << slice));
}
}
static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
unsigned long len,
struct slice_mask available,
int psize)
{
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
unsigned long addr, found, next_end;
struct vm_unmapped_area_info info;
info.flags = 0;
info.length = len;
info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
info.align_offset = 0;
addr = TASK_UNMAPPED_BASE;
while (addr < TASK_SIZE) {
info.low_limit = addr;
if (!slice_scan_available(addr, available, 1, &addr))
continue;
next_slice:
/*
* At this point [info.low_limit; addr) covers
* available slices only and ends at a slice boundary.
* Check if we need to reduce the range, or if we can
* extend it to cover the next available slice.
*/
if (addr >= TASK_SIZE)
addr = TASK_SIZE;
else if (slice_scan_available(addr, available, 1, &next_end)) {
addr = next_end;
goto next_slice;
}
info.high_limit = addr;
found = vm_unmapped_area(&info);
if (!(found & ~PAGE_MASK))
return found;
}
return -ENOMEM;
}
static unsigned long slice_find_area_topdown(struct mm_struct *mm,
unsigned long len,
struct slice_mask available,
int psize)
{
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
unsigned long addr, found, prev;
struct vm_unmapped_area_info info;
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
info.align_offset = 0;
addr = mm->mmap_base;
while (addr > PAGE_SIZE) {
info.high_limit = addr;
if (!slice_scan_available(addr - 1, available, 0, &addr))
continue;
prev_slice:
/*
* At this point [addr; info.high_limit) covers
* available slices only and starts at a slice boundary.
* Check if we need to reduce the range, or if we can
* extend it to cover the previous available slice.
*/
if (addr < PAGE_SIZE)
addr = PAGE_SIZE;
else if (slice_scan_available(addr - 1, available, 0, &prev)) {
addr = prev;
goto prev_slice;
}
info.low_limit = addr;
found = vm_unmapped_area(&info);
if (!(found & ~PAGE_MASK))
return found;
}
/*
* 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.
*/
return slice_find_area_bottomup(mm, len, available, psize);
}
static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
struct slice_mask mask, int psize,
int topdown)
{
if (topdown)
return slice_find_area_topdown(mm, len, mask, psize);
else
return slice_find_area_bottomup(mm, len, mask, psize);
}
#define or_mask(dst, src) do { \
(dst).low_slices |= (src).low_slices; \
(dst).high_slices |= (src).high_slices; \
} while (0)
#define andnot_mask(dst, src) do { \
(dst).low_slices &= ~(src).low_slices; \
(dst).high_slices &= ~(src).high_slices; \
} while (0)
#ifdef CONFIG_PPC_64K_PAGES
#define MMU_PAGE_BASE MMU_PAGE_64K
#else
#define MMU_PAGE_BASE MMU_PAGE_4K
#endif
unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
unsigned long flags, unsigned int psize,
int topdown)
{
struct slice_mask mask = {0, 0};
struct slice_mask good_mask;
struct slice_mask potential_mask = {0,0} /* silence stupid warning */;
struct slice_mask compat_mask = {0, 0};
int fixed = (flags & MAP_FIXED);
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
struct mm_struct *mm = current->mm;
unsigned long newaddr;
/* Sanity checks */
BUG_ON(mm->task_size == 0);
slice_dbg("slice_get_unmapped_area(mm=%p, psize=%d...\n", mm, psize);
slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d\n",
addr, len, flags, topdown);
if (len > mm->task_size)
return -ENOMEM;
if (len & ((1ul << pshift) - 1))
return -EINVAL;
if (fixed && (addr & ((1ul << pshift) - 1)))
return -EINVAL;
if (fixed && addr > (mm->task_size - len))
return -EINVAL;
/* If hint, make sure it matches our alignment restrictions */
if (!fixed && addr) {
addr = _ALIGN_UP(addr, 1ul << pshift);
slice_dbg(" aligned addr=%lx\n", addr);
/* Ignore hint if it's too large or overlaps a VMA */
if (addr > mm->task_size - len ||
!slice_area_is_free(mm, addr, len))
addr = 0;
}
/* First make up a "good" mask of slices that have the right size
* already
*/
good_mask = slice_mask_for_size(mm, psize);
slice_print_mask(" good_mask", good_mask);
/*
* Here "good" means slices that are already the right page size,
* "compat" means slices that have a compatible page size (i.e.
* 4k in a 64k pagesize kernel), and "free" means slices without
* any VMAs.
*
* If MAP_FIXED:
* check if fits in good | compat => OK
* check if fits in good | compat | free => convert free
* else bad
* If have hint:
* check if hint fits in good => OK
* check if hint fits in good | free => convert free
* Otherwise:
* search in good, found => OK
* search in good | free, found => convert free
* search in good | compat | free, found => convert free.
*/
#ifdef CONFIG_PPC_64K_PAGES
/* If we support combo pages, we can allow 64k pages in 4k slices */
if (psize == MMU_PAGE_64K) {
compat_mask = slice_mask_for_size(mm, MMU_PAGE_4K);
if (fixed)
or_mask(good_mask, compat_mask);
}
#endif
/* First check hint if it's valid or if we have MAP_FIXED */
if (addr != 0 || fixed) {
/* Build a mask for the requested range */
mask = slice_range_to_mask(addr, len);
slice_print_mask(" mask", mask);
/* Check if we fit in the good mask. If we do, we just return,
* nothing else to do
*/
if (slice_check_fit(mask, good_mask)) {
slice_dbg(" fits good !\n");
return addr;
}
} else {
/* Now let's see if we can find something in the existing
* slices for that size
*/
newaddr = slice_find_area(mm, len, good_mask, psize, topdown);
if (newaddr != -ENOMEM) {
/* Found within the good mask, we don't have to setup,
* we thus return directly
*/
slice_dbg(" found area at 0x%lx\n", newaddr);
return newaddr;
}
}
/* We don't fit in the good mask, check what other slices are
* empty and thus can be converted
*/
potential_mask = slice_mask_for_free(mm);
or_mask(potential_mask, good_mask);
slice_print_mask(" potential", potential_mask);
if ((addr != 0 || fixed) && slice_check_fit(mask, potential_mask)) {
slice_dbg(" fits potential !\n");
goto convert;
}
/* If we have MAP_FIXED and failed the above steps, then error out */
if (fixed)
return -EBUSY;
slice_dbg(" search...\n");
/* If we had a hint that didn't work out, see if we can fit
* anywhere in the good area.
*/
if (addr) {
addr = slice_find_area(mm, len, good_mask, psize, topdown);
if (addr != -ENOMEM) {
slice_dbg(" found area at 0x%lx\n", addr);
return addr;
}
}
/* Now let's see if we can find something in the existing slices
* for that size plus free slices
*/
addr = slice_find_area(mm, len, potential_mask, psize, topdown);
#ifdef CONFIG_PPC_64K_PAGES
if (addr == -ENOMEM && psize == MMU_PAGE_64K) {
/* retry the search with 4k-page slices included */
or_mask(potential_mask, compat_mask);
addr = slice_find_area(mm, len, potential_mask, psize,
topdown);
}
#endif
if (addr == -ENOMEM)
return -ENOMEM;
mask = slice_range_to_mask(addr, len);
slice_dbg(" found potential area at 0x%lx\n", addr);
slice_print_mask(" mask", mask);
convert:
andnot_mask(mask, good_mask);
andnot_mask(mask, compat_mask);
if (mask.low_slices || mask.high_slices) {
slice_convert(mm, mask, psize);
if (psize > MMU_PAGE_BASE)
on_each_cpu(slice_flush_segments, mm, 1);
}
return addr;
}
EXPORT_SYMBOL_GPL(slice_get_unmapped_area);
unsigned long arch_get_unmapped_area(struct file *filp,
unsigned long addr,
unsigned long len,
unsigned long pgoff,
unsigned long flags)
{
return slice_get_unmapped_area(addr, len, flags,
current->mm->context.user_psize, 0);
}
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)
{
return slice_get_unmapped_area(addr0, len, flags,
current->mm->context.user_psize, 1);
}
unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr)
{
unsigned char *hpsizes;
int index, mask_index;
if (addr < SLICE_LOW_TOP) {
u64 lpsizes;
lpsizes = mm->context.low_slices_psize;
index = GET_LOW_SLICE_INDEX(addr);
return (lpsizes >> (index * 4)) & 0xf;
}
hpsizes = mm->context.high_slices_psize;
index = GET_HIGH_SLICE_INDEX(addr);
mask_index = index & 0x1;
return (hpsizes[index >> 1] >> (mask_index * 4)) & 0xf;
}
EXPORT_SYMBOL_GPL(get_slice_psize);
/*
* This is called by hash_page when it needs to do a lazy conversion of
* an address space from real 64K pages to combo 4K pages (typically
* when hitting a non cacheable mapping on a processor or hypervisor
* that won't allow them for 64K pages).
*
* This is also called in init_new_context() to change back the user
* psize from whatever the parent context had it set to
* N.B. This may be called before mm->context.id has been set.
*
* This function will only change the content of the {low,high)_slice_psize
* masks, it will not flush SLBs as this shall be handled lazily by the
* caller.
*/
void slice_set_user_psize(struct mm_struct *mm, unsigned int psize)
{
int index, mask_index;
unsigned char *hpsizes;
unsigned long flags, lpsizes;
unsigned int old_psize;
int i;
slice_dbg("slice_set_user_psize(mm=%p, psize=%d)\n", mm, psize);
spin_lock_irqsave(&slice_convert_lock, flags);
old_psize = mm->context.user_psize;
slice_dbg(" old_psize=%d\n", old_psize);
if (old_psize == psize)
goto bail;
mm->context.user_psize = psize;
wmb();
lpsizes = mm->context.low_slices_psize;
for (i = 0; i < SLICE_NUM_LOW; i++)
if (((lpsizes >> (i * 4)) & 0xf) == old_psize)
lpsizes = (lpsizes & ~(0xful << (i * 4))) |
(((unsigned long)psize) << (i * 4));
/* Assign the value back */
mm->context.low_slices_psize = lpsizes;
hpsizes = mm->context.high_slices_psize;
for (i = 0; i < SLICE_NUM_HIGH; i++) {
mask_index = i & 0x1;
index = i >> 1;
if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == old_psize)
hpsizes[index] = (hpsizes[index] &
~(0xf << (mask_index * 4))) |
(((unsigned long)psize) << (mask_index * 4));
}
slice_dbg(" lsps=%lx, hsps=%lx\n",
mm->context.low_slices_psize,
mm->context.high_slices_psize);
bail:
spin_unlock_irqrestore(&slice_convert_lock, flags);
}
void slice_set_psize(struct mm_struct *mm, unsigned long address,
unsigned int psize)
{
unsigned char *hpsizes;
unsigned long i, flags;
u64 *lpsizes;
spin_lock_irqsave(&slice_convert_lock, flags);
if (address < SLICE_LOW_TOP) {
i = GET_LOW_SLICE_INDEX(address);
lpsizes = &mm->context.low_slices_psize;
*lpsizes = (*lpsizes & ~(0xful << (i * 4))) |
((unsigned long) psize << (i * 4));
} else {
int index, mask_index;
i = GET_HIGH_SLICE_INDEX(address);
hpsizes = mm->context.high_slices_psize;
mask_index = i & 0x1;
index = i >> 1;
hpsizes[index] = (hpsizes[index] &
~(0xf << (mask_index * 4))) |
(((unsigned long)psize) << (mask_index * 4));
}
spin_unlock_irqrestore(&slice_convert_lock, flags);
#ifdef CONFIG_SPU_BASE
spu_flush_all_slbs(mm);
#endif
}
void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
unsigned long len, unsigned int psize)
{
struct slice_mask mask = slice_range_to_mask(start, len);
slice_convert(mm, mask, psize);
}
/*
* is_hugepage_only_range() is used by generic code to verify whether
* a normal mmap mapping (non hugetlbfs) is valid on a given area.
*
* until the generic code provides a more generic hook and/or starts
* calling arch get_unmapped_area for MAP_FIXED (which our implementation
* here knows how to deal with), we hijack it to keep standard mappings
* away from us.
*
* because of that generic code limitation, MAP_FIXED mapping cannot
* "convert" back a slice with no VMAs to the standard page size, only
* get_unmapped_area() can. It would be possible to fix it here but I
* prefer working on fixing the generic code instead.
*
* WARNING: This will not work if hugetlbfs isn't enabled since the
* generic code will redefine that function as 0 in that. This is ok
* for now as we only use slices with hugetlbfs enabled. This should
* be fixed as the generic code gets fixed.
*/
int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
unsigned long len)
{
struct slice_mask mask, available;
unsigned int psize = mm->context.user_psize;
mask = slice_range_to_mask(addr, len);
available = slice_mask_for_size(mm, psize);
#ifdef CONFIG_PPC_64K_PAGES
/* We need to account for 4k slices too */
if (psize == MMU_PAGE_64K) {
struct slice_mask compat_mask;
compat_mask = slice_mask_for_size(mm, MMU_PAGE_4K);
or_mask(available, compat_mask);
}
#endif
#if 0 /* too verbose */
slice_dbg("is_hugepage_only_range(mm=%p, addr=%lx, len=%lx)\n",
mm, addr, len);
slice_print_mask(" mask", mask);
slice_print_mask(" available", available);
#endif
return !slice_check_fit(mask, available);
}