/*
* These routines also need to handle stuff like marking pages dirty
* and/or accessed for architectures that don't do it in hardware (most
* RISC architectures). The early dirtying is also good on the i386.
*
* There is also a hook called "update_mmu_cache()" that architectures
* with external mmu caches can use to update those (ie the Sparc or
* PowerPC hashed page tables that act as extended TLBs).
*
* Note the "page_table_lock". It is to protect against kswapd removing
* pages from under us. Note that kswapd only ever _removes_ pages, never
* adds them. As such, once we have noticed that the page is not present,
* we can drop the lock early.
*
* The adding of pages is protected by the MM semaphore (which we hold),
* so we don't need to worry about a page being suddenly been added into
* our VM.
*/
static inline int handle_pte_fault(struct mm_struct *mm,
struct vm_area_struct * vma, unsigned long address,
int write_access, pte_t * pte)
{
pte_t entry;
/*
* We need the page table lock to synchronize with kswapd
* and the SMP-safe atomic PTE updates.
*/
spin_lock(&mm->page_table_lock);
entry = *pte;
if (!pte_present(entry)) {
/*
* If it truly wasn't present, we know that kswapd
* and the PTE updates will not touch it later. So
* drop the lock.
*/
spin_unlock(&mm->page_table_lock);
if (pte_none(entry))
return do_no_page(mm, vma, address, write_access, pte);
return do_swap_page(mm, vma, address, pte, pte_to_swp_entry(entry), write_access);
}
if (write_access) {
if (!pte_write(entry))
return do_wp_page(mm, vma, address, pte, entry);
entry = pte_mkdirty(entry);
}
entry = pte_mkyoung(entry);
establish_pte(vma, address, pte, entry);
spin_unlock(&mm->page_table_lock);
return 1;
}
/*
* Changing some bits of contiguous entries requires us to follow a
* Break-Before-Make approach, breaking the whole contiguous set
* before we can change any entries. See ARM DDI 0487A.k_iss10775,
* "Misprogramming of the Contiguous bit", page D4-1762.
*
* This helper performs the break step.
*/
static pte_t get_clear_flush(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep,
unsigned long pgsize,
unsigned long ncontig)
{
pte_t orig_pte = huge_ptep_get(ptep);
bool valid = pte_valid(orig_pte);
unsigned long i, saddr = addr;
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
pte_t pte = ptep_get_and_clear(mm, addr, ptep);
/*
* If HW_AFDBM is enabled, then the HW could turn on
* the dirty or accessed bit for any page in the set,
* so check them all.
*/
if (pte_dirty(pte))
orig_pte = pte_mkdirty(orig_pte);
if (pte_young(pte))
orig_pte = pte_mkyoung(orig_pte);
}
if (valid) {
struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
flush_tlb_range(&vma, saddr, addr);
}
return orig_pte;
}
int huge_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t pte, int dirty)
{
int ncontig, i;
size_t pgsize = 0;
unsigned long pfn = pte_pfn(pte), dpfn;
pgprot_t hugeprot;
pte_t orig_pte;
if (!pte_cont(pte))
return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
dpfn = pgsize >> PAGE_SHIFT;
if (!__cont_access_flags_changed(ptep, pte, ncontig))
return 0;
orig_pte = get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
/* Make sure we don't lose the dirty or young state */
if (pte_dirty(orig_pte))
pte = pte_mkdirty(pte);
if (pte_young(orig_pte))
pte = pte_mkyoung(pte);
hugeprot = pte_pgprot(pte);
for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
set_pte_at(vma->vm_mm, addr, ptep, pfn_pte(pfn, hugeprot));
return 1;
}
/*
* This routine handles present pages, when users try to write
* to a shared page. It is done by copying the page to a new address
* and decrementing the shared-page counter for the old page.
*
* Goto-purists beware: the only reason for goto's here is that it results
* in better assembly code.. The "default" path will see no jumps at all.
*
* Note that this routine assumes that the protection checks have been
* done by the caller (the low-level page fault routine in most cases).
* Thus we can safely just mark it writable once we've done any necessary
* COW.
*
* We also mark the page dirty at this point even though the page will
* change only once the write actually happens. This avoids a few races,
* and potentially makes it more efficient.
*
* We hold the mm semaphore and the page_table_lock on entry and exit
* with the page_table_lock released.
*/
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
unsigned long address, pte_t *page_table, pte_t pte)
{
struct page *old_page, *new_page;
old_page = pte_page(pte);
if (!VALID_PAGE(old_page))
goto bad_wp_page;
if (!TryLockPage(old_page)) {
int reuse = can_share_swap_page(old_page);
unlock_page(old_page);
if (reuse) {
#ifndef CONFIG_SUPERH
/* Not needed for VIPT cache */
flush_cache_page(vma, address);
#endif
establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
spin_unlock(&mm->page_table_lock);
return 1; /* Minor fault */
}
}
/*
* Ok, we need to copy. Oh, well..
*/
page_cache_get(old_page);
spin_unlock(&mm->page_table_lock);
new_page = alloc_page(GFP_HIGHUSER);
if (!new_page)
goto no_mem;
copy_cow_page(old_page,new_page,address);
/*
* Re-check the pte - we dropped the lock
*/
spin_lock(&mm->page_table_lock);
if (pte_same(*page_table, pte)) {
if (PageReserved(old_page))
++mm->rss;
break_cow(vma, new_page, address, page_table);
lru_cache_add(new_page);
/* Free the old page.. */
new_page = old_page;
}
spin_unlock(&mm->page_table_lock);
page_cache_release(new_page);
page_cache_release(old_page);
return 1; /* Minor fault */
bad_wp_page:
spin_unlock(&mm->page_table_lock);
printk("do_wp_page: bogus page at address %08lx (page 0x%lx)\n",address,(unsigned long)old_page);
return -1;
no_mem:
page_cache_release(old_page);
return -1;
}
/*
* the function for the no-page and wp_page
*/
void handle_pte_fault(struct vm_area_struct *vma, unsigned long address, pte_t *pte,int write_access)
{
// no page present
if(!pte_present(*pte))
{
do_no_page(vma,address,write_access);
return;
}
*pte = pte_mkyoung(*pte);
if(!write_access)
{
*pte = pte_mkdirty(*pte);
return;
}
// write the shared page
do_wp_page(vma, address, write_access);
}
/*
* The above separate functions for the no-page and wp-page
* cases will go away (they mostly do the same thing anyway),
* and we'll instead use only a general "handle_mm_fault()".
*
* These routines also need to handle stuff like marking pages dirty
* and/or accessed for architectures that don't do it in hardware (most
* RISC architectures). The early dirtying is also good on the i386.
*
* There is also a hook called "update_mmu_cache()" that architectures
* with external mmu caches can use to update those (ie the Sparc or
* PowerPC hashed page tables that act as extended TLBs).
*/
static inline void handle_pte_fault(struct vm_area_struct * vma, unsigned long address,
int write_access, pte_t * pte)
{
if (!pte_present(*pte)) {
do_no_page(current, vma, address, write_access);
return;
}
set_pte(pte, pte_mkyoung(*pte));
flush_tlb_page(vma, address);
if (!write_access)
return;
if (pte_write(*pte)) {
set_pte(pte, pte_mkdirty(*pte));
flush_tlb_page(vma, address);
return;
}
do_wp_page(current, vma, address, write_access);
}
static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
pte_t *pte, unsigned int flags)
{
/* No page to get reference */
if (flags & FOLL_GET)
return -EFAULT;
if (flags & FOLL_TOUCH) {
pte_t entry = *pte;
if (flags & FOLL_WRITE)
entry = pte_mkdirty(entry);
entry = pte_mkyoung(entry);
if (!pte_same(*pte, entry)) {
set_pte_at(vma->vm_mm, address, pte, entry);
update_mmu_cache(vma, address, pte);
}
}
/* Proper page table entry exists, but no corresponding struct page */
return -EEXIST;
}
/*H:330
* (i) Looking up a page table entry when the Guest faults.
*
* We saw this call in run_guest(): when we see a page fault in the Guest, we
* come here. That's because we only set up the shadow page tables lazily as
* they're needed, so we get page faults all the time and quietly fix them up
* and return to the Guest without it knowing.
*
* If we fixed up the fault (ie. we mapped the address), this routine returns
* true. Otherwise, it was a real fault and we need to tell the Guest.
*/
bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
{
pgd_t gpgd;
pgd_t *spgd;
unsigned long gpte_ptr;
pte_t gpte;
pte_t *spte;
/* Mid level for PAE. */
#ifdef CONFIG_X86_PAE
pmd_t *spmd;
pmd_t gpmd;
#endif
/* First step: get the top-level Guest page table entry. */
if (unlikely(cpu->linear_pages)) {
/* Faking up a linear mapping. */
gpgd = __pgd(CHECK_GPGD_MASK);
} else {
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
return false;
}
/* Now look at the matching shadow entry. */
spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
if (!(pgd_flags(*spgd) & _PAGE_PRESENT)) {
/* No shadow entry: allocate a new shadow PTE page. */
unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
/*
* This is not really the Guest's fault, but killing it is
* simple for this corner case.
*/
if (!ptepage) {
kill_guest(cpu, "out of memory allocating pte page");
return false;
}
/* We check that the Guest pgd is OK. */
check_gpgd(cpu, gpgd);
/*
* And we copy the flags to the shadow PGD entry. The page
* number in the shadow PGD is the page we just allocated.
*/
set_pgd(spgd, __pgd(__pa(ptepage) | pgd_flags(gpgd)));
}
#ifdef CONFIG_X86_PAE
if (unlikely(cpu->linear_pages)) {
/* Faking up a linear mapping. */
gpmd = __pmd(_PAGE_TABLE);
} else {
gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
/* Middle level not present? We can't map it in. */
if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
return false;
}
/* Now look at the matching shadow entry. */
spmd = spmd_addr(cpu, *spgd, vaddr);
if (!(pmd_flags(*spmd) & _PAGE_PRESENT)) {
/* No shadow entry: allocate a new shadow PTE page. */
unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
/*
* This is not really the Guest's fault, but killing it is
* simple for this corner case.
*/
if (!ptepage) {
kill_guest(cpu, "out of memory allocating pte page");
return false;
}
/* We check that the Guest pmd is OK. */
check_gpmd(cpu, gpmd);
/*
* And we copy the flags to the shadow PMD entry. The page
* number in the shadow PMD is the page we just allocated.
*/
set_pmd(spmd, __pmd(__pa(ptepage) | pmd_flags(gpmd)));
}
/*
* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later.
*/
gpte_ptr = gpte_addr(cpu, gpmd, vaddr);
#else
/*
* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later.
*/
gpte_ptr = gpte_addr(cpu, gpgd, vaddr);
#endif
if (unlikely(cpu->linear_pages)) {
/* Linear? Make up a PTE which points to same page. */
gpte = __pte((vaddr & PAGE_MASK) | _PAGE_RW | _PAGE_PRESENT);
} else {
/* Read the actual PTE value. */
gpte = lgread(cpu, gpte_ptr, pte_t);
}
/* If this page isn't in the Guest page tables, we can't page it in. */
if (!(pte_flags(gpte) & _PAGE_PRESENT))
return false;
/*
* Check they're not trying to write to a page the Guest wants
* read-only (bit 2 of errcode == write).
*/
if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
return false;
/* User access to a kernel-only page? (bit 3 == user access) */
if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
return false;
/*
* Check that the Guest PTE flags are OK, and the page number is below
* the pfn_limit (ie. not mapping the Launcher binary).
*/
check_gpte(cpu, gpte);
/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
gpte = pte_mkyoung(gpte);
if (errcode & 2)
gpte = pte_mkdirty(gpte);
/* Get the pointer to the shadow PTE entry we're going to set. */
spte = spte_addr(cpu, *spgd, vaddr);
/*
* If there was a valid shadow PTE entry here before, we release it.
* This can happen with a write to a previously read-only entry.
*/
release_pte(*spte);
/*
* If this is a write, we insist that the Guest page is writable (the
* final arg to gpte_to_spte()).
*/
if (pte_dirty(gpte))
*spte = gpte_to_spte(cpu, gpte, 1);
else
/*
* If this is a read, don't set the "writable" bit in the page
* table entry, even if the Guest says it's writable. That way
* we will come back here when a write does actually occur, so
* we can update the Guest's _PAGE_DIRTY flag.
*/
set_pte(spte, gpte_to_spte(cpu, pte_wrprotect(gpte), 0));
/*
* Finally, we write the Guest PTE entry back: we've set the
* _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags.
*/
if (likely(!cpu->linear_pages))
lgwrite(cpu, gpte_ptr, pte_t, gpte);
/*
* The fault is fixed, the page table is populated, the mapping
* manipulated, the result returned and the code complete. A small
* delay and a trace of alliteration are the only indications the Guest
* has that a page fault occurred at all.
*/
return true;
}
/*
* This routine handles present pages, when users try to write
* to a shared page. It is done by copying the page to a new address
* and decrementing the shared-page counter for the old page.
*
* Goto-purists beware: the only reason for goto's here is that it results
* in better assembly code.. The "default" path will see no jumps at all.
*
* Note that this routine assumes that the protection checks have been
* done by the caller (the low-level page fault routine in most cases).
* Thus we can safely just mark it writable once we've done any necessary
* COW.
*
* We also mark the page dirty at this point even though the page will
* change only once the write actually happens. This avoids a few races,
* and potentially makes it more efficient.
*
* We enter with the page table read-lock held, and need to exit without
* it.
*/
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
unsigned long address, pte_t *page_table, pte_t pte)
{
struct page *old_page, *new_page;
old_page = pte_page(pte);
if (!VALID_PAGE(old_page))
goto bad_wp_page;
/*
* We can avoid the copy if:
* - we're the only user (count == 1)
* - the only other user is the swap cache,
* and the only swap cache user is itself,
* in which case we can just continue to
* use the same swap cache (it will be
* marked dirty).
*/
switch (page_count(old_page)) {
case 2:
/*
* Lock the page so that no one can look it up from
* the swap cache, grab a reference and start using it.
* Can not do lock_page, holding page_table_lock.
*/
if (!PageSwapCache(old_page) || TryLockPage(old_page))
break;
if (is_page_shared(old_page)) {
UnlockPage(old_page);
break;
}
UnlockPage(old_page);
/* FallThrough */
case 1:
flush_cache_page(vma, address);
establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
spin_unlock(&mm->page_table_lock);
return 1; /* Minor fault */
}
/*
* Ok, we need to copy. Oh, well..
*/
spin_unlock(&mm->page_table_lock);
new_page = page_cache_alloc();
if (!new_page)
return -1;
spin_lock(&mm->page_table_lock);
/*
* Re-check the pte - we dropped the lock
*/
if (pte_same(*page_table, pte)) {
if (PageReserved(old_page))
++mm->rss;
break_cow(vma, old_page, new_page, address, page_table);
/* Free the old page.. */
new_page = old_page;
}
spin_unlock(&mm->page_table_lock);
page_cache_release(new_page);
return 1; /* Minor fault */
bad_wp_page:
spin_unlock(&mm->page_table_lock);
printk("do_wp_page: bogus page at address %08lx (page 0x%lx)\n",address,(unsigned long)old_page);
return -1;
}
/*H:330
* (i) Looking up a page table entry when the Guest faults.
*
* We saw this call in run_guest(): when we see a page fault in the Guest, we
* come here. That's because we only set up the shadow page tables lazily as
* they're needed, so we get page faults all the time and quietly fix them up
* and return to the Guest without it knowing.
*
* If we fixed up the fault (ie. we mapped the address), this routine returns
* true. Otherwise, it was a real fault and we need to tell the Guest.
*
* There's a corner case: they're trying to access memory between
* pfn_limit and device_limit, which is I/O memory. In this case, we
* return false and set @iomem to the physical address, so the the
* Launcher can handle the instruction manually.
*/
bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode,
unsigned long *iomem)
{
unsigned long gpte_ptr;
pte_t gpte;
pte_t *spte;
pmd_t gpmd;
pgd_t gpgd;
*iomem = 0;
/* We never demand page the Switcher, so trying is a mistake. */
if (vaddr >= switcher_addr)
return false;
/* First step: get the top-level Guest page table entry. */
if (unlikely(cpu->linear_pages)) {
/* Faking up a linear mapping. */
gpgd = __pgd(CHECK_GPGD_MASK);
} else {
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
return false;
/*
* This kills the Guest if it has weird flags or tries to
* refer to a "physical" address outside the bounds.
*/
if (!check_gpgd(cpu, gpgd))
return false;
}
/* This "mid-level" entry is only used for non-linear, PAE mode. */
gpmd = __pmd(_PAGE_TABLE);
#ifdef CONFIG_X86_PAE
if (likely(!cpu->linear_pages)) {
gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
/* Middle level not present? We can't map it in. */
if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
return false;
/*
* This kills the Guest if it has weird flags or tries to
* refer to a "physical" address outside the bounds.
*/
if (!check_gpmd(cpu, gpmd))
return false;
}
/*
* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later.
*/
gpte_ptr = gpte_addr(cpu, gpmd, vaddr);
#else
/*
* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later.
*/
gpte_ptr = gpte_addr(cpu, gpgd, vaddr);
#endif
if (unlikely(cpu->linear_pages)) {
/* Linear? Make up a PTE which points to same page. */
gpte = __pte((vaddr & PAGE_MASK) | _PAGE_RW | _PAGE_PRESENT);
} else {
/* Read the actual PTE value. */
gpte = lgread(cpu, gpte_ptr, pte_t);
}
/* If this page isn't in the Guest page tables, we can't page it in. */
if (!(pte_flags(gpte) & _PAGE_PRESENT))
return false;
/*
* Check they're not trying to write to a page the Guest wants
* read-only (bit 2 of errcode == write).
*/
if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
return false;
/* User access to a kernel-only page? (bit 3 == user access) */
if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
return false;
/* If they're accessing io memory, we expect a fault. */
if (gpte_in_iomem(cpu, gpte)) {
*iomem = (pte_pfn(gpte) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
return false;
}
/*
* Check that the Guest PTE flags are OK, and the page number is below
* the pfn_limit (ie. not mapping the Launcher binary).
*/
if (!check_gpte(cpu, gpte))
return false;
/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
gpte = pte_mkyoung(gpte);
if (errcode & 2)
gpte = pte_mkdirty(gpte);
/* Get the pointer to the shadow PTE entry we're going to set. */
spte = find_spte(cpu, vaddr, true, pgd_flags(gpgd), pmd_flags(gpmd));
if (!spte)
return false;
/*
* If there was a valid shadow PTE entry here before, we release it.
* This can happen with a write to a previously read-only entry.
*/
release_pte(*spte);
/*
* If this is a write, we insist that the Guest page is writable (the
* final arg to gpte_to_spte()).
*/
if (pte_dirty(gpte))
*spte = gpte_to_spte(cpu, gpte, 1);
else
/*
* If this is a read, don't set the "writable" bit in the page
* table entry, even if the Guest says it's writable. That way
* we will come back here when a write does actually occur, so
* we can update the Guest's _PAGE_DIRTY flag.
*/
set_pte(spte, gpte_to_spte(cpu, pte_wrprotect(gpte), 0));
/*
* Finally, we write the Guest PTE entry back: we've set the
* _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags.
*/
if (likely(!cpu->linear_pages))
lgwrite(cpu, gpte_ptr, pte_t, gpte);
/*
* The fault is fixed, the page table is populated, the mapping
* manipulated, the result returned and the code complete. A small
* delay and a trace of alliteration are the only indications the Guest
* has that a page fault occurred at all.
*/
return true;
}
int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
{
unsigned long flags, mmuar, mmutr;
struct mm_struct *mm;
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
int asid;
local_irq_save(flags);
mmuar = (dtlb) ? mmu_read(MMUAR) :
regs->pc + (extension_word * sizeof(long));
mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
if (!mm) {
local_irq_restore(flags);
return -1;
}
pgd = pgd_offset(mm, mmuar);
if (pgd_none(*pgd)) {
local_irq_restore(flags);
return -1;
}
pmd = pmd_offset(pgd, mmuar);
if (pmd_none(*pmd)) {
local_irq_restore(flags);
return -1;
}
pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
: pte_offset_map(pmd, mmuar);
if (pte_none(*pte) || !pte_present(*pte)) {
local_irq_restore(flags);
return -1;
}
if (write) {
if (!pte_write(*pte)) {
local_irq_restore(flags);
return -1;
}
set_pte(pte, pte_mkdirty(*pte));
}
set_pte(pte, pte_mkyoung(*pte));
asid = mm->context & 0xff;
if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
set_pte(pte, pte_wrprotect(*pte));
mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
mmu_write(MMUTR, mmutr);
mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
if (dtlb)
mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
else
mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
local_irq_restore(flags);
return 0;
}
static int fault_in_page(int taskid,
struct vm_area_struct *vma,
unsigned long address, int write)
{
static unsigned last_address;
static int last_task, loop_counter;
struct task_struct *tsk = task[taskid];
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
if (!tsk || !tsk->mm)
return 1;
if (!vma || (write && !(vma->vm_flags & VM_WRITE)))
goto bad_area;
if (vma->vm_start > address)
goto bad_area;
if (address == last_address && taskid == last_task) {
loop_counter++;
} else {
loop_counter = 0;
last_address = address;
last_task = taskid;
}
if (loop_counter == WRITE_LIMIT && !write) {
printk("MSC bug? setting write request\n");
stats.errors++;
write = 1;
}
if (loop_counter == LOOP_LIMIT) {
printk("MSC bug? failing request\n");
stats.errors++;
return 1;
}
pgd = pgd_offset(vma->vm_mm, address);
pmd = pmd_alloc(pgd,address);
if(!pmd)
goto no_memory;
pte = pte_alloc(pmd, address);
if(!pte)
goto no_memory;
if(!pte_present(*pte)) {
handle_mm_fault(tsk, vma, address, write);
goto finish_up;
}
set_pte(pte, pte_mkyoung(*pte));
flush_tlb_page(vma, address);
if(!write)
goto finish_up;
if(pte_write(*pte)) {
set_pte(pte, pte_mkdirty(*pte));
flush_tlb_page(vma, address);
goto finish_up;
}
handle_mm_fault(tsk, vma, address, write);
/* Fall through for do_wp_page */
finish_up:
stats.success++;
return 0;
no_memory:
stats.failure++;
oom(tsk);
return 1;
bad_area:
stats.failure++;
tsk->tss.sig_address = address;
tsk->tss.sig_desc = SUBSIG_NOMAPPING;
send_sig(SIGSEGV, tsk, 1);
return 1;
}