kernel-fxtec-pro1x/arch/x86_64/mm/fault.c

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/*
* linux/arch/x86-64/mm/fault.c
*
* Copyright (C) 1995 Linus Torvalds
* Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/smp.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>
#include <asm/kdebug.h>
#include <asm-generic/sections.h>
/* Page fault error code bits */
#define PF_PROT (1<<0) /* or no page found */
#define PF_WRITE (1<<1)
#define PF_USER (1<<2)
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
[PATCH] Notify page fault call chain for x86_64 Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: Overloading of page fault notification with the notify_die() has performance issues(since the only interested components for page fault is kprobes and/or kdb) and hence this patch introduces the new notifier call chain exclusively for page fault notifications their by avoiding notifying unnecessary components in the do_page_fault() code path. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 01:25:25 -06:00
/* Hook to register for page fault notifications */
int register_page_fault_notifier(struct notifier_block *nb)
{
vmalloc_sync_all();
return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
}
EXPORT_SYMBOL_GPL(register_page_fault_notifier);
[PATCH] Notify page fault call chain for x86_64 Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: Overloading of page fault notification with the notify_die() has performance issues(since the only interested components for page fault is kprobes and/or kdb) and hence this patch introduces the new notifier call chain exclusively for page fault notifications their by avoiding notifying unnecessary components in the do_page_fault() code path. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 01:25:25 -06:00
int unregister_page_fault_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
}
EXPORT_SYMBOL_GPL(unregister_page_fault_notifier);
[PATCH] Notify page fault call chain for x86_64 Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: Overloading of page fault notification with the notify_die() has performance issues(since the only interested components for page fault is kprobes and/or kdb) and hence this patch introduces the new notifier call chain exclusively for page fault notifications their by avoiding notifying unnecessary components in the do_page_fault() code path. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 01:25:25 -06:00
static inline int notify_page_fault(enum die_val val, const char *str,
struct pt_regs *regs, long err, int trap, int sig)
{
struct die_args args = {
.regs = regs,
.str = str,
.err = err,
.trapnr = trap,
.signr = sig
};
return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
}
void bust_spinlocks(int yes)
{
int loglevel_save = console_loglevel;
if (yes) {
oops_in_progress = 1;
} else {
#ifdef CONFIG_VT
unblank_screen();
#endif
oops_in_progress = 0;
/*
* OK, the message is on the console. Now we call printk()
* without oops_in_progress set so that printk will give klogd
* a poke. Hold onto your hats...
*/
console_loglevel = 15; /* NMI oopser may have shut the console up */
printk(" ");
console_loglevel = loglevel_save;
}
}
/* Sometimes the CPU reports invalid exceptions on prefetch.
Check that here and ignore.
Opcode checker based on code by Richard Brunner */
static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
unsigned long error_code)
{
unsigned char __user *instr;
int scan_more = 1;
int prefetch = 0;
unsigned char *max_instr;
/* If it was a exec fault ignore */
if (error_code & PF_INSTR)
return 0;
instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
max_instr = instr + 15;
if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
return 0;
while (scan_more && instr < max_instr) {
unsigned char opcode;
unsigned char instr_hi;
unsigned char instr_lo;
if (__get_user(opcode, (char __user *)instr))
break;
instr_hi = opcode & 0xf0;
instr_lo = opcode & 0x0f;
instr++;
switch (instr_hi) {
case 0x20:
case 0x30:
/* Values 0x26,0x2E,0x36,0x3E are valid x86
prefixes. In long mode, the CPU will signal
invalid opcode if some of these prefixes are
present so we will never get here anyway */
scan_more = ((instr_lo & 7) == 0x6);
break;
case 0x40:
/* In AMD64 long mode, 0x40 to 0x4F are valid REX prefixes
Need to figure out under what instruction mode the
instruction was issued ... */
/* Could check the LDT for lm, but for now it's good
enough to assume that long mode only uses well known
segments or kernel. */
scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
break;
case 0x60:
/* 0x64 thru 0x67 are valid prefixes in all modes. */
scan_more = (instr_lo & 0xC) == 0x4;
break;
case 0xF0:
/* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */
scan_more = !instr_lo || (instr_lo>>1) == 1;
break;
case 0x00:
/* Prefetch instruction is 0x0F0D or 0x0F18 */
scan_more = 0;
if (__get_user(opcode, (char __user *)instr))
break;
prefetch = (instr_lo == 0xF) &&
(opcode == 0x0D || opcode == 0x18);
break;
default:
scan_more = 0;
break;
}
}
return prefetch;
}
static int bad_address(void *p)
{
unsigned long dummy;
return __get_user(dummy, (unsigned long __user *)p);
}
void dump_pagetable(unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
asm("movq %%cr3,%0" : "=r" (pgd));
pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
pgd += pgd_index(address);
if (bad_address(pgd)) goto bad;
printk("PGD %lx ", pgd_val(*pgd));
if (!pgd_present(*pgd)) goto ret;
pud = pud_offset(pgd, address);
if (bad_address(pud)) goto bad;
printk("PUD %lx ", pud_val(*pud));
if (!pud_present(*pud)) goto ret;
pmd = pmd_offset(pud, address);
if (bad_address(pmd)) goto bad;
printk("PMD %lx ", pmd_val(*pmd));
if (!pmd_present(*pmd)) goto ret;
pte = pte_offset_kernel(pmd, address);
if (bad_address(pte)) goto bad;
printk("PTE %lx", pte_val(*pte));
ret:
printk("\n");
return;
bad:
printk("BAD\n");
}
static const char errata93_warning[] =
KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
KERN_ERR "******* Please consider a BIOS update.\n"
KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
/* Workaround for K8 erratum #93 & buggy BIOS.
BIOS SMM functions are required to use a specific workaround
to avoid corruption of the 64bit RIP register on C stepping K8.
A lot of BIOS that didn't get tested properly miss this.
The OS sees this as a page fault with the upper 32bits of RIP cleared.
Try to work around it here.
Note we only handle faults in kernel here. */
static int is_errata93(struct pt_regs *regs, unsigned long address)
{
static int warned;
if (address != regs->rip)
return 0;
if ((address >> 32) != 0)
return 0;
address |= 0xffffffffUL << 32;
if ((address >= (u64)_stext && address <= (u64)_etext) ||
(address >= MODULES_VADDR && address <= MODULES_END)) {
if (!warned) {
printk(errata93_warning);
warned = 1;
}
regs->rip = address;
return 1;
}
return 0;
}
int unhandled_signal(struct task_struct *tsk, int sig)
{
if (tsk->pid == 1)
return 1;
if (tsk->ptrace & PT_PTRACED)
return 0;
return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
(tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
}
static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
unsigned long error_code)
{
unsigned long flags = oops_begin();
struct task_struct *tsk;
printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
current->comm, address);
dump_pagetable(address);
tsk = current;
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
__die("Bad pagetable", regs, error_code);
oops_end(flags);
do_exit(SIGKILL);
}
/*
* Handle a fault on the vmalloc area
*
* This assumes no large pages in there.
*/
static int vmalloc_fault(unsigned long address)
{
pgd_t *pgd, *pgd_ref;
pud_t *pud, *pud_ref;
pmd_t *pmd, *pmd_ref;
pte_t *pte, *pte_ref;
/* Copy kernel mappings over when needed. This can also
happen within a race in page table update. In the later
case just flush. */
pgd = pgd_offset(current->mm ?: &init_mm, address);
pgd_ref = pgd_offset_k(address);
if (pgd_none(*pgd_ref))
return -1;
if (pgd_none(*pgd))
set_pgd(pgd, *pgd_ref);
else
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
/* Below here mismatches are bugs because these lower tables
are shared */
pud = pud_offset(pgd, address);
pud_ref = pud_offset(pgd_ref, address);
if (pud_none(*pud_ref))
return -1;
if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref))
BUG();
pmd = pmd_offset(pud, address);
pmd_ref = pmd_offset(pud_ref, address);
if (pmd_none(*pmd_ref))
return -1;
if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
BUG();
pte_ref = pte_offset_kernel(pmd_ref, address);
if (!pte_present(*pte_ref))
return -1;
pte = pte_offset_kernel(pmd, address);
/* Don't use pte_page here, because the mappings can point
outside mem_map, and the NUMA hash lookup cannot handle
that. */
if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
BUG();
return 0;
}
int page_fault_trace = 0;
int exception_trace = 1;
/*
* 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 __kprobes do_page_fault(struct pt_regs *regs,
unsigned long error_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long address;
const struct exception_table_entry *fixup;
int write;
unsigned long flags;
siginfo_t info;
tsk = current;
mm = tsk->mm;
prefetchw(&mm->mmap_sem);
/* get the address */
__asm__("movq %%cr2,%0":"=r" (address));
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.
*
* This verifies that the fault happens in kernel space
* (error_code & 4) == 0, and that the fault was not a
* protection error (error_code & 9) == 0.
*/
if (unlikely(address >= TASK_SIZE64)) {
/*
* Don't check for the module range here: its PML4
* is always initialized because it's shared with the main
* kernel text. Only vmalloc may need PML4 syncups.
*/
if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
((address >= VMALLOC_START && address < VMALLOC_END))) {
if (vmalloc_fault(address) >= 0)
return;
}
[PATCH] Notify page fault call chain for x86_64 Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: Overloading of page fault notification with the notify_die() has performance issues(since the only interested components for page fault is kprobes and/or kdb) and hence this patch introduces the new notifier call chain exclusively for page fault notifications their by avoiding notifying unnecessary components in the do_page_fault() code path. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 01:25:25 -06:00
if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
SIGSEGV) == NOTIFY_STOP)
return;
/*
* Don't take the mm semaphore here. If we fixup a prefetch
* fault we could otherwise deadlock.
*/
goto bad_area_nosemaphore;
}
[PATCH] Notify page fault call chain for x86_64 Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: Overloading of page fault notification with the notify_die() has performance issues(since the only interested components for page fault is kprobes and/or kdb) and hence this patch introduces the new notifier call chain exclusively for page fault notifications their by avoiding notifying unnecessary components in the do_page_fault() code path. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 01:25:25 -06:00
if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
SIGSEGV) == NOTIFY_STOP)
return;
if (likely(regs->eflags & X86_EFLAGS_IF))
local_irq_enable();
if (unlikely(page_fault_trace))
printk("pagefault rip:%lx rsp:%lx cs:%lu ss:%lu address %lx error %lx\n",
regs->rip,regs->rsp,regs->cs,regs->ss,address,error_code);
if (unlikely(error_code & PF_RSVD))
pgtable_bad(address, regs, error_code);
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (unlikely(in_atomic() || !mm))
goto bad_area_nosemaphore;
again:
/* 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. Unfortunatly, 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 possibilty 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 ((error_code & PF_USER) == 0 &&
!search_exception_tables(regs->rip))
goto bad_area_nosemaphore;
down_read(&mm->mmap_sem);
}
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (likely(vma->vm_start <= address))
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (error_code & 4) {
/* Allow userspace just enough access below the stack pointer
* to let the 'enter' instruction work.
*/
if (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp)
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;
write = 0;
switch (error_code & (PF_PROT|PF_WRITE)) {
default: /* 3: write, present */
/* fall through */
case PF_WRITE: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
write++;
break;
case PF_PROT: /* read, present */
goto bad_area;
case 0: /* read, not present */
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.
*/
switch (handle_mm_fault(mm, vma, address, write)) {
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
case VM_FAULT_MAJOR:
tsk->maj_flt++;
break;
case VM_FAULT_SIGBUS:
goto do_sigbus;
default:
goto out_of_memory;
}
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 (error_code & PF_USER) {
if (is_prefetch(regs, address, error_code))
return;
/* Work around K8 erratum #100 K8 in compat mode
occasionally jumps to illegal addresses >4GB. We
catch this here in the page fault handler because
these addresses are not reachable. Just detect this
case and return. Any code segment in LDT is
compatibility mode. */
if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
(address >> 32))
return;
if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
printk(
"%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
tsk->comm, tsk->pid, address, regs->rip,
regs->rsp, error_code);
}
tsk->thread.cr2 = address;
/* Kernel addresses are always protection faults */
tsk->thread.error_code = error_code | (address >= TASK_SIZE);
tsk->thread.trap_no = 14;
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? */
fixup = search_exception_tables(regs->rip);
if (fixup) {
regs->rip = fixup->fixup;
return;
}
/*
* Hall of shame of CPU/BIOS bugs.
*/
if (is_prefetch(regs, address, error_code))
return;
if (is_errata93(regs, address))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
flags = oops_begin();
if (address < PAGE_SIZE)
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
else
printk(KERN_ALERT "Unable to handle kernel paging request");
printk(" at %016lx RIP: \n" KERN_ALERT,address);
printk_address(regs->rip);
dump_pagetable(address);
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
__die("Oops", regs, error_code);
/* Executive summary in case the body of the oops scrolled away */
printk(KERN_EMERG "CR2: %016lx\n", address);
oops_end(flags);
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 (current->pid == 1) {
yield();
goto again;
}
printk("VM: killing process %s\n", tsk->comm);
if (error_code & 4)
do_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (!(error_code & PF_USER))
goto no_context;
tsk->thread.cr2 = address;
tsk->thread.error_code = error_code;
tsk->thread.trap_no = 14;
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;
}
DEFINE_SPINLOCK(pgd_lock);
struct page *pgd_list;
void vmalloc_sync_all(void)
{
/* Note that races in the updates of insync and start aren't
problematic:
insync can only get set bits added, and updates to start are only
improving performance (without affecting correctness if undone). */
static DECLARE_BITMAP(insync, PTRS_PER_PGD);
static unsigned long start = VMALLOC_START & PGDIR_MASK;
unsigned long address;
for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) {
if (!test_bit(pgd_index(address), insync)) {
const pgd_t *pgd_ref = pgd_offset_k(address);
struct page *page;
if (pgd_none(*pgd_ref))
continue;
spin_lock(&pgd_lock);
for (page = pgd_list; page;
page = (struct page *)page->index) {
pgd_t *pgd;
pgd = (pgd_t *)page_address(page) + pgd_index(address);
if (pgd_none(*pgd))
set_pgd(pgd, *pgd_ref);
else
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
}
spin_unlock(&pgd_lock);
set_bit(pgd_index(address), insync);
}
if (address == start)
start = address + PGDIR_SIZE;
}
/* Check that there is no need to do the same for the modules area. */
BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
(__START_KERNEL & PGDIR_MASK)));
}
static int __init enable_pagefaulttrace(char *str)
{
page_fault_trace = 1;
return 1;
}
__setup("pagefaulttrace", enable_pagefaulttrace);