static noinline void do_fault_error(struct pt_regs *regs, int fault)
{
int si_code;
switch (fault) {
case VM_FAULT_BADACCESS:
case VM_FAULT_BADMAP:
/* Bad memory access. Check if it is kernel or user space. */
if (user_mode(regs)) {
/* User mode accesses just cause a SIGSEGV */
si_code = (fault == VM_FAULT_BADMAP) ?
SEGV_MAPERR : SEGV_ACCERR;
do_sigsegv(regs, si_code);
return;
}
case VM_FAULT_BADCONTEXT:
do_no_context(regs);
break;
case VM_FAULT_SIGNAL:
if (!user_mode(regs))
do_no_context(regs);
break;
default: /* fault & VM_FAULT_ERROR */
if (fault & VM_FAULT_OOM) {
if (!user_mode(regs))
do_no_context(regs);
else
pagefault_out_of_memory();
} else if (fault & VM_FAULT_SIGBUS) {
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
do_no_context(regs);
else
do_sigbus(regs);
} else
BUG();
break;
}
}
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long vector, int write_acc)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
siginfo_t info;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
tsk = current;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*
* NOTE2: This is done so that, when updating the vmalloc
* mappings we don't have to walk all processes pgdirs and
* add the high mappings all at once. Instead we do it as they
* are used. However vmalloc'ed page entries have the PAGE_GLOBAL
* bit set so sometimes the TLB can use a lingering entry.
*
* This verifies that the fault happens in kernel space
* and that the fault was not a protection error.
*/
if (address >= VMALLOC_START &&
(vector != 0x300 && vector != 0x400) &&
!user_mode(regs))
goto vmalloc_fault;
/* If exceptions were enabled, we can reenable them here */
if (user_mode(regs)) {
/* Exception was in userspace: reenable interrupts */
local_irq_enable();
} else {
/* If exception was in a syscall, then IRQ's may have
* been enabled or disabled. If they were enabled,
* reenable them.
*/
if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE))
local_irq_enable();
}
mm = tsk->mm;
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_interrupt() || !mm)
goto no_context;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (user_mode(regs)) {
/*
* accessing the stack below usp is always a bug.
* we get page-aligned addresses so we can only check
* if we're within a page from usp, but that might be
* enough to catch brutal errors at least.
*/
if (address + PAGE_SIZE < regs->sp)
goto bad_area;
}
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
/* first do some preliminary protection checks */
if (write_acc) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else {
/* not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
/* are we trying to execute nonexecutable area */
if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC))
goto bad_area;
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
/*RGD modeled on Cris */
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void *)address;
force_sig_info(SIGSEGV, &info, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault?
*
* (The kernel has valid exception-points in the source
* when it acesses user-memory. When it fails in one
* of those points, we find it in a table and do a jump
* to some fixup code that loads an appropriate error
* code)
*/
{
const struct exception_table_entry *entry;
__asm__ __volatile__("l.nop 42");
if ((entry = search_exception_tables(regs->pc)) != NULL) {
/* Adjust the instruction pointer in the stackframe */
regs->pc = entry->fixup;
return;
}
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if ((unsigned long)(address) < PAGE_SIZE)
printk(KERN_ALERT
"Unable to handle kernel NULL pointer dereference");
else
printk(KERN_ALERT "Unable to handle kernel access");
printk(" at virtual address 0x%08lx\n", address);
die("Oops", regs, write_acc);
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
__asm__ __volatile__("l.nop 42");
__asm__ __volatile__("l.nop 1");
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *)address;
force_sig_info(SIGBUS, &info, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
return;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Use current_pgd instead of tsk->active_mm->pgd
* since the latter might be unavailable if this
* code is executed in a misfortunately run irq
* (like inside schedule() between switch_mm and
* switch_to...).
*/
int offset = pgd_index(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
/*
phx_warn("do_page_fault(): vmalloc_fault will not work, "
"since current_pgd assign a proper value somewhere\n"
"anyhow we don't need this at the moment\n");
phx_mmu("vmalloc_fault");
*/
pgd = (pgd_t *)current_pgd + offset;
pgd_k = init_mm.pgd + offset;
/* Since we're two-level, we don't need to do both
* set_pgd and set_pmd (they do the same thing). If
* we go three-level at some point, do the right thing
* with pgd_present and set_pgd here.
*
* Also, since the vmalloc area is global, we don't
* need to copy individual PTE's, it is enough to
* copy the pgd pointer into the pte page of the
* root task. If that is there, we'll find our pte if
* it exists.
*/
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto no_context;
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto bad_area_nosemaphore;
set_pmd(pmd, *pmd_k);
/* Make sure the actual PTE exists as well to
* catch kernel vmalloc-area accesses to non-mapped
* addresses. If we don't do this, this will just
* silently loop forever.
*/
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
return;
}
}
/*
* This routine handles page faults. It determines the problem, and
* then passes it off to one of the appropriate routines.
*
* error_code:
* bit 0 == 0 means no page found, 1 means protection fault
* bit 1 == 0 means read, 1 means write
*
* If this routine detects a bad access, it returns 1, otherwise it
* returns 0.
*/
int do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long error_code)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct * vma;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (faulthandler_disabled() || !mm)
goto no_context;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto map_err;
if (vma->vm_flags & VM_IO)
goto acc_err;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto map_err;
if (user_mode(regs)) {
/* Accessing the stack below usp is always a bug. The
"+ 256" is there due to some instructions doing
pre-decrement on the stack and that doesn't show up
until later. */
if (address + 256 < rdusp())
goto map_err;
}
if (expand_stack(vma, address))
goto map_err;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
pr_debug("do_page_fault: good_area\n");
switch (error_code & 3) {
default: /* 3: write, present */
/* fall through */
case 2: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto acc_err;
flags |= FAULT_FLAG_WRITE;
break;
case 1: /* read, present */
goto acc_err;
case 0: /* read, not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto acc_err;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(vma, address, flags);
pr_debug("handle_mm_fault returns %d\n", fault);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return 0;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGSEGV)
goto map_err;
else if (fault & VM_FAULT_SIGBUS)
goto bus_err;
BUG();
}
/*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely
* likely that the page will be found in page cache at that point.
*/
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/*
* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
return 0;
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
return 0;
no_context:
current->thread.signo = SIGBUS;
current->thread.faddr = address;
return send_fault_sig(regs);
bus_err:
current->thread.signo = SIGBUS;
current->thread.code = BUS_ADRERR;
current->thread.faddr = address;
goto send_sig;
map_err:
current->thread.signo = SIGSEGV;
current->thread.code = SEGV_MAPERR;
current->thread.faddr = address;
goto send_sig;
acc_err:
current->thread.signo = SIGSEGV;
current->thread.code = SEGV_ACCERR;
current->thread.faddr = address;
send_sig:
up_read(&mm->mmap_sem);
return send_fault_sig(regs);
}
/*
* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
* segv().
*/
int handle_page_fault(unsigned long address, unsigned long ip,
int is_write, int is_user, int *code_out)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
int err = -EFAULT;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
(is_write ? FAULT_FLAG_WRITE : 0);
*code_out = SEGV_MAPERR;
/*
* If the fault was during atomic operation, don't take the fault, just
* fail.
*/
if (in_atomic())
goto out_nosemaphore;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto out;
else if (vma->vm_start <= address)
goto good_area;
else if (!(vma->vm_flags & VM_GROWSDOWN))
goto out;
else if (is_user && !ARCH_IS_STACKGROW(address))
goto out;
else if (expand_stack(vma, address))
goto out;
good_area:
*code_out = SEGV_ACCERR;
if (is_write && !(vma->vm_flags & VM_WRITE))
goto out;
/* Don't require VM_READ|VM_EXEC for write faults! */
if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
goto out;
do {
int fault;
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
goto out_nosemaphore;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM) {
goto out_of_memory;
} else if (fault & VM_FAULT_SIGBUS) {
err = -EACCES;
goto out;
}
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
pgd = pgd_offset(mm, address);
pud = pud_offset(pgd, address);
pmd = pmd_offset(pud, address);
pte = pte_offset_kernel(pmd, address);
} while (!pte_present(*pte));
err = 0;
/*
* The below warning was added in place of
* pte_mkyoung(); if (is_write) pte_mkdirty();
* If it's triggered, we'd see normally a hang here (a clean pte is
* marked read-only to emulate the dirty bit).
* However, the generic code can mark a PTE writable but clean on a
* concurrent read fault, triggering this harmlessly. So comment it out.
*/
#if 0
WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
#endif
flush_tlb_page(vma, address);
out:
up_read(&mm->mmap_sem);
out_nosemaphore:
return err;
out_of_memory:
/*
* We ran out of memory, call the OOM killer, and return the userspace
* (which will retry the fault, or kill us if we got oom-killed).
*/
up_read(&mm->mmap_sem);
pagefault_out_of_memory();
return 0;
}
/*
* This routine handles page faults. It determines the address and the
* problem, and then passes it off to one of the appropriate routines.
*/
asmlinkage void do_page_fault(struct pt_regs *regs)
{
struct task_struct *tsk;
struct vm_area_struct *vma;
struct mm_struct *mm;
unsigned long addr, cause;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
int fault, code = SEGV_MAPERR;
cause = regs->scause;
addr = regs->sbadaddr;
tsk = current;
mm = tsk->mm;
/*
* Fault-in kernel-space virtual memory on-demand.
* The 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (unlikely((addr >= VMALLOC_START) && (addr <= VMALLOC_END)))
goto vmalloc_fault;
/* Enable interrupts if they were enabled in the parent context. */
if (likely(regs->sstatus & SR_PIE))
local_irq_enable();
/*
* If we're in an interrupt, have no user context, or are running
* in an atomic region, then we must not take the fault.
*/
if (unlikely(in_atomic() || !mm))
goto no_context;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, addr);
if (unlikely(!vma))
goto bad_area;
if (likely(vma->vm_start <= addr))
goto good_area;
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
goto bad_area;
if (unlikely(expand_stack(vma, addr)))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it.
*/
good_area:
code = SEGV_ACCERR;
switch (cause) {
case EXC_INST_ACCESS:
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
break;
case EXC_LOAD_ACCESS:
if (!(vma->vm_flags & VM_READ))
goto bad_area;
break;
case EXC_STORE_ACCESS:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
break;
default:
panic("%s: unhandled cause %lu", __func__, cause);
}
/*
* If for any reason at all we could not handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, addr, flags);
/*
* If we need to retry but a fatal signal is pending, handle the
* signal first. We do not need to release the mmap_sem because it
* would already be released in __lock_page_or_retry in mm/filemap.c.
*/
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(tsk))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
/*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely
* likely that the page will be found in page cache at that point.
*/
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, addr);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, addr);
}
if (fault & VM_FAULT_RETRY) {
/*
* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation.
*/
flags &= ~(FAULT_FLAG_ALLOW_RETRY);
flags |= FAULT_FLAG_TRIED;
/*
* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map.
* Fix it, but check if it's kernel or user first.
*/
bad_area:
up_read(&mm->mmap_sem);
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
do_trap(regs, SIGSEGV, code, addr, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs)) {
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
bust_spinlocks(1);
pr_alert("Unable to handle kernel %s at virtual address " REG_FMT "\n",
(addr < PAGE_SIZE) ? "NULL pointer dereference" :
"paging request", addr);
die(regs, "Oops");
do_exit(SIGKILL);
/*
* We ran out of memory, call the OOM killer, and return the userspace
* (which will retry the fault, or kill us if we got oom-killed).
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
do_trap(regs, SIGBUS, BUS_ADRERR, addr, tsk);
return;
vmalloc_fault:
{
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
int index;
if (user_mode(regs))
goto bad_area;
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Do _not_ use "tsk->active_mm->pgd" here.
* We might be inside an interrupt in the middle
* of a task switch.
*/
index = pgd_index(addr);
pgd = (pgd_t *)pfn_to_virt(csr_read(sptbr)) + index;
pgd_k = init_mm.pgd + index;
if (!pgd_present(*pgd_k))
goto no_context;
set_pgd(pgd, *pgd_k);
pud = pud_offset(pgd, addr);
pud_k = pud_offset(pgd_k, addr);
if (!pud_present(*pud_k))
goto no_context;
/* Since the vmalloc area is global, it is unnecessary
to copy individual PTEs */
pmd = pmd_offset(pud, addr);
pmd_k = pmd_offset(pud_k, addr);
if (!pmd_present(*pmd_k))
goto no_context;
set_pmd(pmd, *pmd_k);
/* Make sure the actual PTE exists as well to
* catch kernel vmalloc-area accesses to non-mapped
* addresses. If we don't do this, this will just
* silently loop forever.
*/
pte_k = pte_offset_kernel(pmd_k, addr);
if (!pte_present(*pte_k))
goto no_context;
return;
}
}
asmlinkage void
do_page_fault(unsigned long address, struct pt_regs *regs,
int protection, int writeaccess)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
siginfo_t info;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
D(printk(KERN_DEBUG
"Page fault for %lX on %X at %lX, prot %d write %d\n",
address, smp_processor_id(), instruction_pointer(regs),
protection, writeaccess));
tsk = current;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*
* NOTE2: This is done so that, when updating the vmalloc
* mappings we don't have to walk all processes pgdirs and
* add the high mappings all at once. Instead we do it as they
* are used. However vmalloc'ed page entries have the PAGE_GLOBAL
* bit set so sometimes the TLB can use a lingering entry.
*
* This verifies that the fault happens in kernel space
* and that the fault was not a protection error (error_code & 1).
*/
if (address >= VMALLOC_START &&
!protection &&
!user_mode(regs))
goto vmalloc_fault;
/* When stack execution is not allowed we store the signal
* trampolines in the reserved cris_signal_return_page.
* Handle this in the exact same way as vmalloc (we know
* that the mapping is there and is valid so no need to
* call handle_mm_fault).
*/
if (cris_signal_return_page &&
address == cris_signal_return_page &&
!protection && user_mode(regs))
goto vmalloc_fault;
/* we can and should enable interrupts at this point */
local_irq_enable();
mm = tsk->mm;
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or "atomic" operation or have no
* user context, we must not take the fault.
*/
if (!mm || pagefault_disabled())
goto no_context;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (user_mode(regs)) {
/*
* accessing the stack below usp is always a bug.
* we get page-aligned addresses so we can only check
* if we're within a page from usp, but that might be
* enough to catch brutal errors at least.
*/
if (address + PAGE_SIZE < rdusp())
goto bad_area;
}
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
/* first do some preliminary protection checks */
if (writeaccess == 2){
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
} else if (writeaccess == 1) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/*
* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
DPG(show_registers(regs));
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
printk(KERN_NOTICE "%s (pid %d) segfaults for page "
"address %08lx at pc %08lx\n",
tsk->comm, tsk->pid,
address, instruction_pointer(regs));
/* With DPG on, we've already dumped registers above. */
DPG(if (0))
show_registers(regs);
#ifdef CONFIG_NO_SEGFAULT_TERMINATION
DECLARE_WAIT_QUEUE_HEAD(wq);
wait_event_interruptible(wq, 0 == 1);
#else
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void *)address;
force_sig_info(SIGSEGV, &info, tsk);
#endif
return;
}
no_context:
/* Are we prepared to handle this kernel fault?
*
* (The kernel has valid exception-points in the source
* when it accesses user-memory. When it fails in one
* of those points, we find it in a table and do a jump
* to some fixup code that loads an appropriate error
* code)
*/
if (find_fixup_code(regs))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if (!oops_in_progress) {
oops_in_progress = 1;
if ((unsigned long) (address) < PAGE_SIZE)
printk(KERN_ALERT "Unable to handle kernel NULL "
"pointer dereference");
else
printk(KERN_ALERT "Unable to handle kernel access"
" at virtual address %08lx\n", address);
die_if_kernel("Oops", regs, (writeaccess << 1) | protection);
oops_in_progress = 0;
}
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *)address;
force_sig_info(SIGBUS, &info, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
return;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Use current_pgd instead of tsk->active_mm->pgd
* since the latter might be unavailable if this
* code is executed in a misfortunately run irq
* (like inside schedule() between switch_mm and
* switch_to...).
*/
int offset = pgd_index(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + offset;
pgd_k = init_mm.pgd + offset;
/* Since we're two-level, we don't need to do both
* set_pgd and set_pmd (they do the same thing). If
* we go three-level at some point, do the right thing
* with pgd_present and set_pgd here.
*
* Also, since the vmalloc area is global, we don't
* need to copy individual PTE's, it is enough to
* copy the pgd pointer into the pte page of the
* root task. If that is there, we'll find our pte if
* it exists.
*/
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto no_context;
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto bad_area_nosemaphore;
set_pmd(pmd, *pmd_k);
/* Make sure the actual PTE exists as well to
* catch kernel vmalloc-area accesses to non-mapped
* addresses. If we don't do this, this will just
* silently loop forever.
*/
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
return;
}
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
unsigned long address)
{
struct vm_area_struct *vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
int code = SEGV_MAPERR;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
cause >>= 2;
/* Restart the instruction */
regs->ea -= 4;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) {
if (user_mode(regs))
goto bad_area_nosemaphore;
else
goto vmalloc_fault;
}
if (unlikely(address >= TASK_SIZE))
goto bad_area_nosemaphore;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (faulthandler_disabled() || !mm)
goto bad_area_nosemaphore;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
if (!down_read_trylock(&mm->mmap_sem)) {
if (!user_mode(regs) && !search_exception_tables(regs->ea))
goto bad_area_nosemaphore;
retry:
down_read(&mm->mmap_sem);
}
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
code = SEGV_ACCERR;
switch (cause) {
case EXC_SUPERV_INSN_ACCESS:
goto bad_area;
case EXC_SUPERV_DATA_ACCESS:
goto bad_area;
case EXC_X_PROTECTION_FAULT:
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
break;
case EXC_R_PROTECTION_FAULT:
if (!(vma->vm_flags & VM_READ))
goto bad_area;
break;
case EXC_W_PROTECTION_FAULT:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags = FAULT_FLAG_WRITE;
break;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGSEGV)
goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
/*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely
* likely that the page will be found in page cache at that point.
*/
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/*
* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) {
pr_info("%s: unhandled page fault (%d) at 0x%08lx, "
"cause %ld\n", current->comm, SIGSEGV, address, cause);
show_regs(regs);
}
_exception(SIGSEGV, regs, code, address);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
bust_spinlocks(1);
pr_alert("Unable to handle kernel %s at virtual address %08lx",
address < PAGE_SIZE ? "NULL pointer dereference" :
"paging request", address);
pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra,
cause);
panic("Oops");
return;
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
_exception(SIGBUS, regs, BUS_ADRERR, address);
return;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Do _not_ use "tsk" here. We might be inside
* an interrupt in the middle of a task switch..
*/
int offset = pgd_index(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
pgd = pgd_current + offset;
pgd_k = init_mm.pgd + offset;
if (!pgd_present(*pgd_k))
goto no_context;
set_pgd(pgd, *pgd_k);
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto no_context;
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto no_context;
set_pmd(pmd, *pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
flush_tlb_one(address);
return;
}
}
void do_page_fault(struct pt_regs *regs)
{
struct vm_area_struct * vma;
struct mm_struct *mm = current->mm;
unsigned int exccause = regs->exccause;
unsigned int address = regs->excvaddr;
siginfo_t info;
int is_write, is_exec;
int fault;
info.si_code = SEGV_MAPERR;
if (address >= TASK_SIZE && !user_mode(regs))
goto vmalloc_fault;
if (in_atomic() || !mm) {
bad_page_fault(regs, address, SIGSEGV);
return;
}
is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
exccause == EXCCAUSE_ITLB_MISS ||
exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;
#ifdef DEBUG_PAGE_FAULT
printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
good_area:
info.si_code = SEGV_ACCERR;
if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else if (is_exec) {
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
} else
if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
goto bad_area;
fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
up_read(&mm->mmap_sem);
return;
bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
current->thread.bad_vaddr = address;
current->thread.error_code = is_write;
info.si_signo = SIGSEGV;
info.si_errno = 0;
info.si_addr = (void *) address;
force_sig_info(SIGSEGV, &info, current);
return;
}
bad_page_fault(regs, address, SIGSEGV);
return;
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
bad_page_fault(regs, address, SIGKILL);
else
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
current->thread.bad_vaddr = address;
info.si_code = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *) address;
force_sig_info(SIGBUS, &info, current);
if (!user_mode(regs))
bad_page_fault(regs, address, SIGBUS);
vmalloc_fault:
{
struct mm_struct *act_mm = current->active_mm;
int index = pgd_index(address);
pgd_t *pgd, *pgd_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
if (act_mm == NULL)
goto bad_page_fault;
pgd = act_mm->pgd + index;
pgd_k = init_mm.pgd + index;
if (!pgd_present(*pgd_k))
goto bad_page_fault;
pgd_val(*pgd) = pgd_val(*pgd_k);
pmd = pmd_offset(pgd, address);
pmd_k = pmd_offset(pgd_k, address);
if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
goto bad_page_fault;
pmd_val(*pmd) = pmd_val(*pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto bad_page_fault;
return;
}
bad_page_fault:
bad_page_fault(regs, address, SIGKILL);
return;
}
/*
* This routine is responsible for faulting in user pages.
* It passes the work off to one of the appropriate routines.
* It returns true if the fault was successfully handled.
*/
static int handle_page_fault(struct pt_regs *regs,
int fault_num,
int is_page_fault,
unsigned long address,
int write)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned long stack_offset;
int fault;
int si_code;
int is_kernel_mode;
pgd_t *pgd;
/* on TILE, protection faults are always writes */
if (!is_page_fault)
write = 1;
flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
is_kernel_mode = (EX1_PL(regs->ex1) != USER_PL);
tsk = validate_current();
/*
* Check to see if we might be overwriting the stack, and bail
* out if so. The page fault code is a relatively likely
* place to get trapped in an infinite regress, and once we
* overwrite the whole stack, it becomes very hard to recover.
*/
stack_offset = stack_pointer & (THREAD_SIZE-1);
if (stack_offset < THREAD_SIZE / 8) {
pr_alert("Potential stack overrun: sp %#lx\n",
stack_pointer);
show_regs(regs);
pr_alert("Killing current process %d/%s\n",
tsk->pid, tsk->comm);
do_group_exit(SIGKILL);
}
/*
* Early on, we need to check for migrating PTE entries;
* see homecache.c. If we find a migrating PTE, we wait until
* the backing page claims to be done migrating, then we proceed.
* For kernel PTEs, we rewrite the PTE and return and retry.
* Otherwise, we treat the fault like a normal "no PTE" fault,
* rather than trying to patch up the existing PTE.
*/
pgd = get_current_pgd();
if (handle_migrating_pte(pgd, fault_num, address, regs->pc,
is_kernel_mode, write))
return 1;
si_code = SEGV_MAPERR;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*
* This verifies that the fault happens in kernel space
* and that the fault was not a protection fault.
*/
if (unlikely(address >= TASK_SIZE &&
!is_arch_mappable_range(address, 0))) {
if (is_kernel_mode && is_page_fault &&
vmalloc_fault(pgd, address) >= 0)
return 1;
/*
* Don't take the mm semaphore here. If we fixup a prefetch
* fault we could otherwise deadlock.
*/
mm = NULL; /* happy compiler */
vma = NULL;
goto bad_area_nosemaphore;
}
/*
* If we're trying to touch user-space addresses, we must
* be either at PL0, or else with interrupts enabled in the
* kernel, so either way we can re-enable interrupts here
* unless we are doing atomic access to user space with
* interrupts disabled.
*/
if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
local_irq_enable();
mm = tsk->mm;
/*
* If we're in an interrupt, have no user context or are running in an
* atomic region then we must not take the fault.
*/
if (in_atomic() || !mm) {
vma = NULL; /* happy compiler */
goto bad_area_nosemaphore;
}
if (!is_kernel_mode)
flags |= FAULT_FLAG_USER;
/*
* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
* erroneous fault occurring in a code path which already holds mmap_sem
* we will deadlock attempting to validate the fault against the
* address space. Luckily the kernel only validly references user
* space from well defined areas of code, which are listed in the
* exceptions table.
*
* As the vast majority of faults will be valid we will only perform
* the source reference check when there is a possibility of a deadlock.
* Attempt to lock the address space, if we cannot we then validate the
* source. If this is invalid we can skip the address space check,
* thus avoiding the deadlock.
*/
if (!down_read_trylock(&mm->mmap_sem)) {
if (is_kernel_mode &&
!search_exception_tables(regs->pc)) {
vma = NULL; /* happy compiler */
goto bad_area_nosemaphore;
}
down_read(&mm->mmap_sem);
}
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (regs->sp < PAGE_OFFSET) {
/*
* accessing the stack below sp is always a bug.
*/
if (address < regs->sp)
goto bad_area;
}
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
si_code = SEGV_ACCERR;
if (fault_num == INT_ITLB_MISS) {
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
} else if (write) {
#ifdef TEST_VERIFY_AREA
if (!is_page_fault && regs->cs == KERNEL_CS)
pr_err("WP fault at "REGFMT"\n", regs->eip);
#endif
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else {
if (!is_page_fault || !(vma->vm_flags & VM_READ))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, write);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
/*
* If this was an asynchronous fault,
* restart the appropriate engine.
*/
switch (fault_num) {
#if CHIP_HAS_TILE_DMA()
case INT_DMATLB_MISS:
case INT_DMATLB_MISS_DWNCL:
case INT_DMATLB_ACCESS:
case INT_DMATLB_ACCESS_DWNCL:
__insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
break;
#endif
#if CHIP_HAS_SN_PROC()
case INT_SNITLB_MISS:
case INT_SNITLB_MISS_DWNCL:
__insn_mtspr(SPR_SNCTL,
__insn_mfspr(SPR_SNCTL) &
~SPR_SNCTL__FRZPROC_MASK);
break;
#endif
}
#endif
up_read(&mm->mmap_sem);
return 1;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (!is_kernel_mode) {
/*
* It's possible to have interrupts off here.
*/
local_irq_enable();
force_sig_info_fault("segfault", SIGSEGV, si_code, address,
fault_num, tsk, regs);
return 0;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return 0;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
bust_spinlocks(1);
/* FIXME: no lookup_address() yet */
#ifdef SUPPORT_LOOKUP_ADDRESS
if (fault_num == INT_ITLB_MISS) {
pte_t *pte = lookup_address(address);
if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
pr_crit("kernel tried to execute"
" non-executable page - exploit attempt?"
" (uid: %d)\n", current->uid);
}
#endif
if (address < PAGE_SIZE)
pr_alert("Unable to handle kernel NULL pointer dereference\n");
else
pr_alert("Unable to handle kernel paging request\n");
pr_alert(" at virtual address "REGFMT", pc "REGFMT"\n",
address, regs->pc);
show_regs(regs);
if (unlikely(tsk->pid < 2)) {
panic("Kernel page fault running %s!",
is_idle_task(tsk) ? "the idle task" : "init");
}
/*
* More FIXME: we should probably copy the i386 here and
* implement a generic die() routine. Not today.
*/
#ifdef SUPPORT_DIE
die("Oops", regs);
#endif
bust_spinlocks(1);
do_group_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (is_kernel_mode)
goto no_context;
pagefault_out_of_memory();
return 0;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (is_kernel_mode)
goto no_context;
force_sig_info_fault("bus error", SIGBUS, BUS_ADRERR, address,
fault_num, tsk, regs);
return 0;
}
void do_page_fault(unsigned long address, struct pt_regs *regs)
{
struct vm_area_struct *vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
siginfo_t info;
int fault, ret;
int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (address >= VMALLOC_START && address <= VMALLOC_END) {
ret = handle_vmalloc_fault(address);
if (unlikely(ret))
goto bad_area_nosemaphore;
else
return;
}
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto no_context;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
/* Handle protection violation, execute on heap or stack */
if ((regs->ecr_vec == ECR_V_PROTV) &&
(regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
goto bad_area;
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, flags);
/* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
if (unlikely(fatal_signal_pending(current))) {
if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
up_read(&mm->mmap_sem);
if (user_mode(regs))
return;
}
if (likely(!(fault & VM_FAULT_ERROR))) {
if (flags & FAULT_FLAG_ALLOW_RETRY) {
/* To avoid updating stats twice for retry case */
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
/* Fault Handled Gracefully */
up_read(&mm->mmap_sem);
return;
}
/* TBD: switch to pagefault_out_of_memory() */
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
/* no man's land */
BUG();
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
tsk->thread.fault_address = address;
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void __user *)address;
force_sig_info(SIGSEGV, &info, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault?
*
* (The kernel has valid exception-points in the source
* when it acesses user-memory. When it fails in one
* of those points, we find it in a table and do a jump
* to some fixup code that loads an appropriate error
* code)
*/
if (fixup_exception(regs))
return;
die("Oops", regs, address);
out_of_memory:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
pagefault_out_of_memory();
return;
}
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
tsk->thread.fault_address = address;
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void __user *)address;
force_sig_info(SIGBUS, &info, tsk);
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
unsigned long address)
{
struct vm_area_struct * vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
const int field = sizeof(unsigned long) * 2;
siginfo_t info;
int fault;
#if 0
printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
current->comm, current->pid, field, address, write,
field, regs->cp0_epc);
#endif
info.si_code = SEGV_MAPERR;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
goto vmalloc_fault;
#ifdef MODULE_START
if (unlikely(address >= MODULE_START && address < MODULE_END))
goto vmalloc_fault;
#endif
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto bad_area_nosemaphore;
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
tsk->thread.cp0_badvaddr = address;
tsk->thread.error_code = write;
#if 0
printk("do_page_fault() #2: sending SIGSEGV to %s for "
"invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
tsk->comm,
write ? "write access to" : "read access from",
field, address,
field, (unsigned long) regs->cp0_epc,
field, (unsigned long) regs->regs[31]);
#endif
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void __user *) address;
force_sig_info(SIGSEGV, &info, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs)) {
current->thread.cp0_baduaddr = address;
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
bust_spinlocks(1);
printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
"virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
raw_smp_processor_id(), field, address, field, regs->cp0_epc,
field, regs->regs[31]);
die("Oops", regs);
out_of_memory:
/*
* We ran out of memory, call the OOM killer, and return the userspace
* (which will retry the fault, or kill us if we got oom-killed).
*/
up_read(&mm->mmap_sem);
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
else
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
#if 0
printk("do_page_fault() #3: sending SIGBUS to %s for "
"invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
tsk->comm,
write ? "write access to" : "read access from",
field, address,
field, (unsigned long) regs->cp0_epc,
field, (unsigned long) regs->regs[31]);
#endif
tsk->thread.cp0_badvaddr = address;
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void __user *) address;
force_sig_info(SIGBUS, &info, tsk);
return;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Do _not_ use "tsk" here. We might be inside
* an interrupt in the middle of a task switch..
*/
int offset = __pgd_offset(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
pgd_k = init_mm.pgd + offset;
if (!pgd_present(*pgd_k))
goto no_context;
set_pgd(pgd, *pgd_k);
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto no_context;
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto no_context;
set_pmd(pmd, *pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
return;
}
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
unsigned long mmu_meh)
{
struct vm_area_struct *vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
int si_code;
int fault;
unsigned long address = mmu_meh & PAGE_MASK;
si_code = SEGV_MAPERR;
#ifndef CONFIG_CPU_HAS_TLBI
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (unlikely(address >= VMALLOC_START) &&
unlikely(address <= VMALLOC_END)) {
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Do _not_ use "tsk" here. We might be inside
* an interrupt in the middle of a task switch..
*/
int offset = __pgd_offset(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
unsigned long pgd_base;
pgd_base = tlb_get_pgd();
pgd = (pgd_t *)pgd_base + offset;
pgd_k = init_mm.pgd + offset;
if (!pgd_present(*pgd_k))
goto no_context;
set_pgd(pgd, *pgd_k);
pud = (pud_t *)pgd;
pud_k = (pud_t *)pgd_k;
if (!pud_present(*pud_k))
goto no_context;
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto no_context;
set_pmd(pmd, *pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
return;
}
#endif
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto bad_area_nosemaphore;
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
si_code = SEGV_ACCERR;
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
else if (fault & VM_FAULT_SIGSEGV)
goto bad_area;
BUG();
}
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
force_sig_fault(SIGSEGV, si_code, (void __user *)address, current);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
bust_spinlocks(1);
pr_alert("Unable to handle kernel paging request at virtual "
"address 0x%08lx, pc: 0x%08lx\n", address, regs->pc);
die_if_kernel("Oops", regs, write);
out_of_memory:
/*
* We ran out of memory, call the OOM killer, and return the userspace
* (which will retry the fault, or kill us if we got oom-killed).
*/
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, current);
}
void do_page_fault(struct pt_regs *regs)
{
struct vm_area_struct * vma;
struct mm_struct *mm = current->mm;
unsigned int exccause = regs->exccause;
unsigned int address = regs->excvaddr;
siginfo_t info;
int is_write, is_exec;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
info.si_code = SEGV_MAPERR;
/* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*/
if (address >= TASK_SIZE && !user_mode(regs))
goto vmalloc_fault;
/* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (faulthandler_disabled() || !mm) {
bad_page_fault(regs, address, SIGSEGV);
return;
}
is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
exccause == EXCCAUSE_ITLB_MISS ||
exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;
#ifdef DEBUG_PAGE_FAULT
printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else if (is_exec) {
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
} else /* Allow read even from write-only pages. */
if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
goto bad_area;
/* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGSEGV)
goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
if (flags & VM_FAULT_MAJOR)
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
else
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
return;
/* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
current->thread.bad_vaddr = address;
current->thread.error_code = is_write;
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void *) address;
force_sig_info(SIGSEGV, &info, current);
return;
}
bad_page_fault(regs, address, SIGSEGV);
return;
/* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
bad_page_fault(regs, address, SIGKILL);
else
pagefault_out_of_memory();
return;
do_sigbus:
up_read(&mm->mmap_sem);
/* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
current->thread.bad_vaddr = address;
info.si_code = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *) address;
force_sig_info(SIGBUS, &info, current);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
bad_page_fault(regs, address, SIGBUS);
return;
vmalloc_fault:
{
/* Synchronize this task's top level page-table
* with the 'reference' page table.
*/
struct mm_struct *act_mm = current->active_mm;
int index = pgd_index(address);
pgd_t *pgd, *pgd_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
if (act_mm == NULL)
goto bad_page_fault;
pgd = act_mm->pgd + index;
pgd_k = init_mm.pgd + index;
if (!pgd_present(*pgd_k))
goto bad_page_fault;
pgd_val(*pgd) = pgd_val(*pgd_k);
pmd = pmd_offset(pgd, address);
pmd_k = pmd_offset(pgd_k, address);
if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
goto bad_page_fault;
pmd_val(*pmd) = pmd_val(*pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto bad_page_fault;
return;
}
bad_page_fault:
bad_page_fault(regs, address, SIGKILL);
return;
}
/*
* Canonical page fault handler
*/
void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
siginfo_t info;
int si_code = SEGV_MAPERR;
int fault;
const struct exception_table_entry *fixup;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
/*
* If we're in an interrupt or have no user context,
* then must not take the fault.
*/
if (unlikely(in_interrupt() || !mm))
goto no_context;
local_irq_enable();
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
good_area:
/* Address space is OK. Now check access rights. */
si_code = SEGV_ACCERR;
switch (cause) {
case FLT_IFETCH:
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
break;
case FLT_LOAD:
if (!(vma->vm_flags & VM_READ))
goto bad_area;
break;
case FLT_STORE:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
break;
}
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
/* The most common case -- we are done. */
if (likely(!(fault & VM_FAULT_ERROR))) {
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
up_read(&mm->mmap_sem);
return;
}
up_read(&mm->mmap_sem);
/* Handle copyin/out exception cases */
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
return;
}
/* User-mode address is in the memory map, but we are
* unable to fix up the page fault.
*/
if (fault & VM_FAULT_SIGBUS) {
info.si_signo = SIGBUS;
info.si_code = BUS_ADRERR;
}
/* Address is not in the memory map */
else {
info.si_signo = SIGSEGV;
info.si_code = SEGV_ACCERR;
}
info.si_errno = 0;
info.si_addr = (void __user *)address;
force_sig_info(info.si_signo, &info, current);
return;
bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
info.si_signo = SIGSEGV;
info.si_errno = 0;
info.si_code = si_code;
info.si_addr = (void *)address;
force_sig_info(info.si_signo, &info, current);
return;
}
/* Kernel-mode fault falls through */
no_context:
fixup = search_exception_tables(pt_elr(regs));
if (fixup) {
pt_set_elr(regs, fixup->fixup);
return;
}
/* Things are looking very, very bad now */
bust_spinlocks(1);
printk(KERN_EMERG "Unable to handle kernel paging request at "
"virtual address 0x%08lx, regs %p\n", address, regs);
die("Bad Kernel VA", regs, SIGKILL);
}
/*
* This routine handles page faults. It determines the problem, and
* then passes it off to one of the appropriate routines.
*
* error_code:
* bit 0 == 0 means no page found, 1 means protection fault
* bit 1 == 0 means read, 1 means write
*
* If this routine detects a bad access, it returns 1, otherwise it
* returns 0.
*/
int do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long error_code)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct * vma;
int write, fault;
#ifdef DEBUG
printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
regs->sr, regs->pc, address, error_code,
current->mm->pgd);
#endif
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto no_context;
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto map_err;
if (vma->vm_flags & VM_IO)
goto acc_err;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto map_err;
if (user_mode(regs)) {
/* Accessing the stack below usp is always a bug. The
"+ 256" is there due to some instructions doing
pre-decrement on the stack and that doesn't show up
until later. */
if (address + 256 < rdusp())
goto map_err;
}
if (expand_stack(vma, address))
goto map_err;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
#ifdef DEBUG
printk("do_page_fault: good_area\n");
#endif
write = 0;
switch (error_code & 3) {
default: /* 3: write, present */
/* fall through */
case 2: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto acc_err;
write++;
break;
case 1: /* read, present */
goto acc_err;
case 0: /* read, not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto acc_err;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
#ifdef DEBUG
printk("handle_mm_fault returns %d\n",fault);
#endif
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto bus_err;
BUG();
}
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
up_read(&mm->mmap_sem);
return 0;
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
return 0;
no_context:
current->thread.signo = SIGBUS;
current->thread.faddr = address;
return send_fault_sig(regs);
bus_err:
current->thread.signo = SIGBUS;
current->thread.code = BUS_ADRERR;
current->thread.faddr = address;
goto send_sig;
map_err:
current->thread.signo = SIGSEGV;
current->thread.code = SEGV_MAPERR;
current->thread.faddr = address;
goto send_sig;
acc_err:
current->thread.signo = SIGSEGV;
current->thread.code = SEGV_ACCERR;
current->thread.faddr = address;
send_sig:
up_read(&mm->mmap_sem);
return send_fault_sig(regs);
}
static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
tsk = current;
mm = tsk->mm;
/* Enable interrupts if they were enabled in the parent context. */
if (interrupts_enabled(regs))
local_irq_enable();
/*
* If we're in an interrupt or have no user context, we must not take
* the fault.
*/
if (in_atomic() || !mm)
goto no_context;
if (user_mode(regs))
mm_flags |= FAULT_FLAG_USER;
if (esr & ESR_LNX_EXEC) {
vm_flags = VM_EXEC;
} else if ((esr & ESR_EL1_WRITE) && !(esr & ESR_EL1_CM)) {
vm_flags = VM_WRITE;
mm_flags |= FAULT_FLAG_WRITE;
}
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
* we can bug out early if this is from code which shouldn't.
*/
if (!down_read_trylock(&mm->mmap_sem)) {
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
retry:
down_read(&mm->mmap_sem);
} else {
/*
* The above down_read_trylock() might have succeeded in which
* case, we'll have missed the might_sleep() from down_read().
*/
might_sleep();
#ifdef CONFIG_DEBUG_VM
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
#endif
}
fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
/*
* If we need to retry but a fatal signal is pending, handle the
* signal first. We do not need to release the mmap_sem because it
* would already be released in __lock_page_or_retry in mm/filemap.c.
*/
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return 0;
/*
* Major/minor page fault accounting is only done on the initial
* attempt. If we go through a retry, it is extremely likely that the
* page will be found in page cache at that point.
*/
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
addr);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
addr);
}
if (fault & VM_FAULT_RETRY) {
/*
* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
* starvation.
*/
mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
mm_flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
up_read(&mm->mmap_sem);
/*
* Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
*/
if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
VM_FAULT_BADACCESS))))
return 0;
/*
* If we are in kernel mode at this point, we have no context to
* handle this fault with.
*/
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
/*
* We ran out of memory, call the OOM killer, and return to
* userspace (which will retry the fault, or kill us if we got
* oom-killed).
*/
pagefault_out_of_memory();
return 0;
}
if (fault & VM_FAULT_SIGBUS) {
/*
* We had some memory, but were unable to successfully fix up
* this page fault.
*/
sig = SIGBUS;
code = BUS_ADRERR;
} else {
/*
* Something tried to access memory that isn't in our memory
* map.
*/
sig = SIGSEGV;
code = fault == VM_FAULT_BADACCESS ?
SEGV_ACCERR : SEGV_MAPERR;
}
__do_user_fault(tsk, addr, esr, sig, code, regs);
return 0;
no_context:
__do_kernel_fault(mm, addr, esr, regs);
return 0;
}
static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
tsk = current;
mm = tsk->mm;
if (interrupts_enabled(regs))
local_irq_enable();
if (in_atomic() || !mm)
goto no_context;
if (user_mode(regs))
mm_flags |= FAULT_FLAG_USER;
if (esr & ESR_LNX_EXEC) {
vm_flags = VM_EXEC;
} else if (esr & ESR_EL1_WRITE) {
vm_flags = VM_WRITE;
mm_flags |= FAULT_FLAG_WRITE;
}
if (!down_read_trylock(&mm->mmap_sem)) {
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
retry:
down_read(&mm->mmap_sem);
} else {
might_sleep();
#ifdef CONFIG_DEBUG_VM
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
#endif
}
fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return 0;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
addr);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
addr);
}
if (fault & VM_FAULT_RETRY) {
mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
mm_flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
up_read(&mm->mmap_sem);
if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
VM_FAULT_BADACCESS))))
return 0;
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
return 0;
}
if (fault & VM_FAULT_SIGBUS) {
sig = SIGBUS;
code = BUS_ADRERR;
} else {
sig = SIGSEGV;
code = fault == VM_FAULT_BADACCESS ?
SEGV_ACCERR : SEGV_MAPERR;
}
__do_user_fault(tsk, addr, esr, sig, code, regs);
return 0;
no_context:
__do_kernel_fault(mm, addr, esr, regs);
return 0;
}