x86: unify fault_32|64.c
Harvey Harrison [Wed, 30 Jan 2008 12:34:11 +0000 (13:34 +0100)]
Unify includes in moved fault.c.

Modify Makefiles to pick up unified file.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/mm/Makefile_32
arch/x86/mm/Makefile_64
arch/x86/mm/fault.c [moved from arch/x86/mm/fault_64.c with 98% similarity]
arch/x86/mm/fault_32.c [deleted file]

index ffa6d46..c36ae88 100644 (file)
@@ -2,7 +2,7 @@
 # Makefile for the linux i386-specific parts of the memory manager.
 #
 
-obj-y  := init_32.o pgtable_32.o fault_32.o ioremap.o extable.o pageattr.o mmap.o
+obj-y  := init_32.o pgtable_32.o fault.o ioremap.o extable.o pageattr.o mmap.o
 
 obj-$(CONFIG_NUMA) += discontig_32.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
index 27a090c..688c8c2 100644 (file)
@@ -2,7 +2,7 @@
 # Makefile for the linux x86_64-specific parts of the memory manager.
 #
 
-obj-y   := init_64.o fault_64.o ioremap.o extable.o pageattr.o mmap.o
+obj-y   := init_64.o fault.o ioremap.o extable.o pageattr.o mmap.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
 obj-$(CONFIG_NUMA) += numa_64.o
 obj-$(CONFIG_K8_NUMA) += k8topology_64.o
similarity index 98%
rename from arch/x86/mm/fault_64.c
rename to arch/x86/mm/fault.c
index 0902719..14a0c6e 100644 (file)
@@ -18,6 +18,8 @@
 #include <linux/tty.h>
 #include <linux/vt_kern.h>             /* For unblank_screen() */
 #include <linux/compiler.h>
+#include <linux/highmem.h>
+#include <linux/bootmem.h>             /* for max_low_pfn */
 #include <linux/vmalloc.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
@@ -25,6 +27,8 @@
 #include <linux/kdebug.h>
 
 #include <asm/system.h>
+#include <asm/desc.h>
+#include <asm/segment.h>
 #include <asm/pgalloc.h>
 #include <asm/smp.h>
 #include <asm/tlbflush.h>
@@ -88,16 +92,15 @@ static int is_prefetch(struct pt_regs *regs, unsigned long addr,
        unsigned char *max_instr;
 
 #ifdef CONFIG_X86_32
-       if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
-                    boot_cpu_data.x86 >= 6)) {
-               /* Catch an obscure case of prefetch inside an NX page. */
-               if (nx_enabled && (error_code & PF_INSTR))
-                       return 0;
-       } else {
+# ifdef CONFIG_X86_PAE
+       /* If it was a exec fault on NX page, ignore */
+       if (nx_enabled && (error_code & PF_INSTR))
                return 0;
-       }
-#else
-       /* If it was a exec fault ignore */
+# else
+       return 0;
+# endif
+#else /* CONFIG_X86_64 */
+       /* If it was a exec fault on NX page, ignore */
        if (error_code & PF_INSTR)
                return 0;
 #endif
diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c
deleted file mode 100644 (file)
index 4da4625..0000000
+++ /dev/null
@@ -1,949 +0,0 @@
-/*
- *  Copyright (C) 1995  Linus Torvalds
- */
-
-#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/interrupt.h>
-#include <linux/init.h>
-#include <linux/tty.h>
-#include <linux/vt_kern.h>             /* For unblank_screen() */
-#include <linux/highmem.h>
-#include <linux/bootmem.h>             /* for max_low_pfn */
-#include <linux/vmalloc.h>
-#include <linux/module.h>
-#include <linux/kprobes.h>
-#include <linux/uaccess.h>
-#include <linux/kdebug.h>
-
-#include <asm/system.h>
-#include <asm/desc.h>
-#include <asm/segment.h>
-
-/*
- * Page fault error code bits
- *     bit 0 == 0 means no page found, 1 means protection fault
- *     bit 1 == 0 means read, 1 means write
- *     bit 2 == 0 means kernel, 1 means user-mode
- *     bit 3 == 1 means use of reserved bit detected
- *     bit 4 == 1 means fault was an instruction fetch
- */
-#define PF_PROT                (1<<0)
-#define PF_WRITE       (1<<1)
-#define PF_USER                (1<<2)
-#define PF_RSVD                (1<<3)
-#define PF_INSTR       (1<<4)
-
-static inline int notify_page_fault(struct pt_regs *regs)
-{
-#ifdef CONFIG_KPROBES
-       int ret = 0;
-
-       /* kprobe_running() needs smp_processor_id() */
-#ifdef CONFIG_X86_32
-       if (!user_mode_vm(regs)) {
-#else
-       if (!user_mode(regs)) {
-#endif
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, 14))
-                       ret = 1;
-               preempt_enable();
-       }
-
-       return ret;
-#else
-       return 0;
-#endif
-}
-
-/*
- * X86_32
- * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
- * Check that here and ignore it.
- *
- * X86_64
- * Sometimes the CPU reports invalid exceptions on prefetch.
- * Check that here and ignore it.
- *
- * Opcode checker based on code by Richard Brunner
- */
-static int is_prefetch(struct pt_regs *regs, unsigned long addr,
-                      unsigned long error_code)
-{
-       unsigned char *instr;
-       int scan_more = 1;
-       int prefetch = 0;
-       unsigned char *max_instr;
-
-#ifdef CONFIG_X86_32
-       if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
-                    boot_cpu_data.x86 >= 6)) {
-               /* Catch an obscure case of prefetch inside an NX page. */
-               if (nx_enabled && (error_code & PF_INSTR))
-                       return 0;
-       } else {
-               return 0;
-       }
-#else
-       /* If it was a exec fault ignore */
-       if (error_code & PF_INSTR)
-               return 0;
-#endif
-
-       instr = (unsigned char *)convert_ip_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 (probe_kernel_address(instr, opcode))
-                       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 X86_64 long mode, the CPU will signal invalid
-                        * opcode if some of these prefixes are present so
-                        * X86_64 will never get here anyway
-                        */
-                       scan_more = ((instr_lo & 7) == 0x6);
-                       break;
-#ifdef CONFIG_X86_64
-               case 0x40:
-                       /*
-                        * In AMD64 long mode 0x40..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;
-#endif
-               case 0x60:
-                       /* 0x64 thru 0x67 are valid prefixes in all modes. */
-                       scan_more = (instr_lo & 0xC) == 0x4;
-                       break;
-               case 0xF0:
-                       /* 0xF0, 0xF2, 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 (probe_kernel_address(instr, opcode))
-                               break;
-                       prefetch = (instr_lo == 0xF) &&
-                               (opcode == 0x0D || opcode == 0x18);
-                       break;
-               default:
-                       scan_more = 0;
-                       break;
-               }
-       }
-       return prefetch;
-}
-
-static void force_sig_info_fault(int si_signo, int si_code,
-       unsigned long address, struct task_struct *tsk)
-{
-       siginfo_t info;
-
-       info.si_signo = si_signo;
-       info.si_errno = 0;
-       info.si_code = si_code;
-       info.si_addr = (void __user *)address;
-       force_sig_info(si_signo, &info, tsk);
-}
-
-#ifdef CONFIG_X86_64
-static int bad_address(void *p)
-{
-       unsigned long dummy;
-       return probe_kernel_address((unsigned long *)p, dummy);
-}
-#endif
-
-void dump_pagetable(unsigned long address)
-{
-#ifdef CONFIG_X86_32
-       __typeof__(pte_val(__pte(0))) page;
-
-       page = read_cr3();
-       page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
-#ifdef CONFIG_X86_PAE
-       printk("*pdpt = %016Lx ", page);
-       if ((page >> PAGE_SHIFT) < max_low_pfn
-           && page & _PAGE_PRESENT) {
-               page &= PAGE_MASK;
-               page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
-                                                        & (PTRS_PER_PMD - 1)];
-               printk(KERN_CONT "*pde = %016Lx ", page);
-               page &= ~_PAGE_NX;
-       }
-#else
-       printk("*pde = %08lx ", page);
-#endif
-
-       /*
-        * We must not directly access the pte in the highpte
-        * case if the page table is located in highmem.
-        * And let's rather not kmap-atomic the pte, just in case
-        * it's allocated already.
-        */
-       if ((page >> PAGE_SHIFT) < max_low_pfn
-           && (page & _PAGE_PRESENT)
-           && !(page & _PAGE_PSE)) {
-               page &= PAGE_MASK;
-               page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
-                                                        & (PTRS_PER_PTE - 1)];
-               printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
-       }
-
-       printk("\n");
-#else /* CONFIG_X86_64 */
-       pgd_t *pgd;
-       pud_t *pud;
-       pmd_t *pmd;
-       pte_t *pte;
-
-       pgd = (pgd_t *)read_cr3();
-
-       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) || pmd_large(*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");
-#endif
-}
-
-#ifdef CONFIG_X86_32
-static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
-{
-       unsigned index = pgd_index(address);
-       pgd_t *pgd_k;
-       pud_t *pud, *pud_k;
-       pmd_t *pmd, *pmd_k;
-
-       pgd += index;
-       pgd_k = init_mm.pgd + index;
-
-       if (!pgd_present(*pgd_k))
-               return NULL;
-
-       /*
-        * set_pgd(pgd, *pgd_k); here would be useless on PAE
-        * and redundant with the set_pmd() on non-PAE. As would
-        * set_pud.
-        */
-
-       pud = pud_offset(pgd, address);
-       pud_k = pud_offset(pgd_k, address);
-       if (!pud_present(*pud_k))
-               return NULL;
-
-       pmd = pmd_offset(pud, address);
-       pmd_k = pmd_offset(pud_k, address);
-       if (!pmd_present(*pmd_k))
-               return NULL;
-       if (!pmd_present(*pmd)) {
-               set_pmd(pmd, *pmd_k);
-               arch_flush_lazy_mmu_mode();
-       } else
-               BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
-       return pmd_k;
-}
-#endif
-
-#ifdef CONFIG_X86_64
-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";
-#endif
-
-/* 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.
-   Does nothing for X86_32
- */
-static int is_errata93(struct pt_regs *regs, unsigned long address)
-{
-#ifdef CONFIG_X86_64
-       static int warned;
-       if (address != regs->ip)
-               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->ip = address;
-               return 1;
-       }
-#endif
-       return 0;
-}
-
-/*
- * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
- * addresses >4GB.  We catch this 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.
- */
-static int is_errata100(struct pt_regs *regs, unsigned long address)
-{
-#ifdef CONFIG_X86_64
-       if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
-           (address >> 32))
-               return 1;
-#endif
-       return 0;
-}
-
-void do_invalid_op(struct pt_regs *, unsigned long);
-
-static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
-{
-#ifdef CONFIG_X86_F00F_BUG
-       unsigned long nr;
-       /*
-        * Pentium F0 0F C7 C8 bug workaround.
-        */
-       if (boot_cpu_data.f00f_bug) {
-               nr = (address - idt_descr.address) >> 3;
-
-               if (nr == 6) {
-                       do_invalid_op(regs, 0);
-                       return 1;
-               }
-       }
-#endif
-       return 0;
-}
-
-static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
-                           unsigned long address)
-{
-#ifdef CONFIG_X86_32
-       if (!oops_may_print())
-               return;
-
-#ifdef CONFIG_X86_PAE
-       if (error_code & PF_INSTR) {
-               int level;
-               pte_t *pte = lookup_address(address, &level);
-
-               if (pte && pte_present(*pte) && !pte_exec(*pte))
-                       printk(KERN_CRIT "kernel tried to execute "
-                               "NX-protected page - exploit attempt? "
-                               "(uid: %d)\n", current->uid);
-       }
-#endif
-       printk(KERN_ALERT "BUG: unable to handle kernel ");
-       if (address < PAGE_SIZE)
-               printk(KERN_CONT "NULL pointer dereference");
-       else
-               printk(KERN_CONT "paging request");
-       printk(KERN_CONT " at %08lx\n", address);
-
-       printk(KERN_ALERT "IP:");
-       printk_address(regs->ip, 1);
-       dump_pagetable(address);
-#else /* CONFIG_X86_64 */
-       printk(KERN_ALERT "BUG: unable to handle kernel ");
-       if (address < PAGE_SIZE)
-               printk(KERN_CONT "NULL pointer dereference");
-       else
-               printk(KERN_CONT "paging request");
-       printk(KERN_CONT " at %016lx\n", address);
-
-       printk(KERN_ALERT "IP:");
-       printk_address(regs->ip, 1);
-       dump_pagetable(address);
-#endif
-}
-
-#ifdef CONFIG_X86_64
-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;
-       if (__die("Bad pagetable", regs, error_code))
-               regs = NULL;
-       oops_end(flags, regs, SIGKILL);
-}
-#endif
-
-/*
- * X86_32
- * Handle a fault on the vmalloc or module mapping area
- *
- * X86_64
- * Handle a fault on the vmalloc area
- *
- * This assumes no large pages in there.
- */
-static int vmalloc_fault(unsigned long address)
-{
-#ifdef CONFIG_X86_32
-       unsigned long pgd_paddr;
-       pmd_t *pmd_k;
-       pte_t *pte_k;
-       /*
-        * Synchronize this task's top level page-table
-        * with the 'reference' page table.
-        *
-        * Do _not_ use "current" here. We might be inside
-        * an interrupt in the middle of a task switch..
-        */
-       pgd_paddr = read_cr3();
-       pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
-       if (!pmd_k)
-               return -1;
-       pte_k = pte_offset_kernel(pmd_k, address);
-       if (!pte_present(*pte_k))
-               return -1;
-       return 0;
-#else
-       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;
-#endif
-}
-
-int show_unhandled_signals = 1;
-
-/*
- * This routine handles page faults.  It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
- */
-#ifdef CONFIG_X86_64
-asmlinkage
-#endif
-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;
-       int write, si_code;
-       int fault;
-#ifdef CONFIG_X86_64
-       unsigned long flags;
-#endif
-
-       /*
-        * We can fault from pretty much anywhere, with unknown IRQ state.
-        */
-       trace_hardirqs_fixup();
-
-       tsk = current;
-       mm = tsk->mm;
-       prefetchw(&mm->mmap_sem);
-
-       /* get the address */
-       address = read_cr2();
-
-       si_code = SEGV_MAPERR;
-
-       if (notify_page_fault(regs))
-               return;
-
-       /*
-        * 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.
-        */
-#ifdef CONFIG_X86_32
-       if (unlikely(address >= TASK_SIZE)) {
-               if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
-                   vmalloc_fault(address) >= 0)
-                       return;
-               /*
-                * Don't take the mm semaphore here. If we fixup a prefetch
-                * fault we could otherwise deadlock.
-                */
-               goto bad_area_nosemaphore;
-       }
-
-       /* It's safe to allow irq's after cr2 has been saved and the vmalloc
-          fault has been handled. */
-       if (regs->flags & (X86_EFLAGS_IF|VM_MASK))
-               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 (in_atomic() || !mm)
-               goto bad_area_nosemaphore;
-#else /* CONFIG_X86_64 */
-       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;
-               }
-               /*
-                * Don't take the mm semaphore here. If we fixup a prefetch
-                * fault we could otherwise deadlock.
-                */
-               goto bad_area_nosemaphore;
-       }
-       if (likely(regs->flags & X86_EFLAGS_IF))
-               local_irq_enable();
-
-       if (unlikely(error_code & PF_RSVD))
-               pgtable_bad(address, regs, error_code);
-
-       /*
-        * 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 bad_area_nosemaphore;
-
-       /*
-        * User-mode registers count as a user access even for any
-        * potential system fault or CPU buglet.
-        */
-       if (user_mode_vm(regs))
-               error_code |= PF_USER;
-again:
-#endif
-       /* 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 ((error_code & PF_USER) == 0 &&
-                   !search_exception_tables(regs->ip))
-                       goto bad_area_nosemaphore;
-               down_read(&mm->mmap_sem);
-       }
-
-       vma = find_vma(mm, address);
-       if (!vma)
-               goto bad_area;
-#ifdef CONFIG_X86_32
-       if (vma->vm_start <= address)
-#else
-       if (likely(vma->vm_start <= address))
-#endif
-               goto good_area;
-       if (!(vma->vm_flags & VM_GROWSDOWN))
-               goto bad_area;
-       if (error_code & PF_USER) {
-               /*
-                * Accessing the stack below %sp is always a bug.
-                * The large cushion allows instructions like enter
-                * and pusha to work.  ("enter $65535,$31" pushes
-                * 32 pointers and then decrements %sp by 65535.)
-                */
-               if (address + 65536 + 32 * sizeof(unsigned long) < 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;
-       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 | VM_WRITE)))
-                       goto bad_area;
-       }
-
-#ifdef CONFIG_X86_32
-survive:
-#endif
-       /*
-        * 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++;
-
-#ifdef CONFIG_X86_32
-       /*
-        * Did it hit the DOS screen memory VA from vm86 mode?
-        */
-       if (v8086_mode(regs)) {
-               unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
-               if (bit < 32)
-                       tsk->thread.screen_bitmap |= 1 << bit;
-       }
-#endif
-       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) {
-               /*
-                * It's possible to have interrupts off here.
-                */
-               local_irq_enable();
-
-               /*
-                * Valid to do another page fault here because this one came
-                * from user space.
-                */
-               if (is_prefetch(regs, address, error_code))
-                       return;
-
-               if (is_errata100(regs, address))
-                       return;
-
-               if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
-                   printk_ratelimit()) {
-                       printk(
-#ifdef CONFIG_X86_32
-                       "%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx",
-#else
-                       "%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx",
-#endif
-                       task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
-                       tsk->comm, task_pid_nr(tsk), address, regs->ip,
-                       regs->sp, error_code);
-                       print_vma_addr(" in ", regs->ip);
-                       printk("\n");
-               }
-
-               tsk->thread.cr2 = address;
-               /* Kernel addresses are always protection faults */
-               tsk->thread.error_code = error_code | (address >= TASK_SIZE);
-               tsk->thread.trap_no = 14;
-               force_sig_info_fault(SIGSEGV, si_code, address, tsk);
-               return;
-       }
-
-       if (is_f00f_bug(regs, address))
-               return;
-
-no_context:
-       /* Are we prepared to handle this kernel fault?  */
-       if (fixup_exception(regs))
-               return;
-
-       /*
-        * X86_32
-        * Valid to do another page fault here, because if this fault
-        * had been triggered by is_prefetch fixup_exception would have
-        * handled it.
-        *
-        * X86_64
-        * 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.
- */
-#ifdef CONFIG_X86_32
-       bust_spinlocks(1);
-
-       show_fault_oops(regs, error_code, address);
-
-       tsk->thread.cr2 = address;
-       tsk->thread.trap_no = 14;
-       tsk->thread.error_code = error_code;
-       die("Oops", regs, error_code);
-       bust_spinlocks(0);
-       do_exit(SIGKILL);
-#else /* CONFIG_X86_64 */
-       flags = oops_begin();
-
-       show_fault_oops(regs, error_code, address);
-
-       tsk->thread.cr2 = address;
-       tsk->thread.trap_no = 14;
-       tsk->thread.error_code = error_code;
-       if (__die("Oops", regs, error_code))
-               regs = NULL;
-       /* Executive summary in case the body of the oops scrolled away */
-       printk(KERN_EMERG "CR2: %016lx\n", address);
-       oops_end(flags, regs, SIGKILL);
-#endif
-
-/*
- * 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);
-#ifdef CONFIG_X86_32
-       if (is_global_init(tsk)) {
-               yield();
-               down_read(&mm->mmap_sem);
-               goto survive;
-       }
-#else
-       if (is_global_init(current)) {
-               yield();
-               goto again;
-       }
-#endif
-       printk("VM: killing process %s\n", tsk->comm);
-       if (error_code & PF_USER)
-               do_group_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;
-#ifdef CONFIG_X86_32
-       /* User space => ok to do another page fault */
-       if (is_prefetch(regs, address, error_code))
-               return;
-#endif
-       tsk->thread.cr2 = address;
-       tsk->thread.error_code = error_code;
-       tsk->thread.trap_no = 14;
-       force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
-}
-
-#ifdef CONFIG_X86_64
-DEFINE_SPINLOCK(pgd_lock);
-LIST_HEAD(pgd_list);
-#endif
-
-void vmalloc_sync_all(void)
-{
-#ifdef CONFIG_X86_32
-       /*
-        * 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 = TASK_SIZE;
-       unsigned long address;
-
-       if (SHARED_KERNEL_PMD)
-               return;
-
-       BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
-       for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
-               if (!test_bit(pgd_index(address), insync)) {
-                       unsigned long flags;
-                       struct page *page;
-
-                       spin_lock_irqsave(&pgd_lock, flags);
-                       for (page = pgd_list; page; page =
-                                       (struct page *)page->index)
-                               if (!vmalloc_sync_one(page_address(page),
-                                                               address)) {
-                                       BUG_ON(page != pgd_list);
-                                       break;
-                               }
-                       spin_unlock_irqrestore(&pgd_lock, flags);
-                       if (!page)
-                               set_bit(pgd_index(address), insync);
-               }
-               if (address == start && test_bit(pgd_index(address), insync))
-                       start = address + PGDIR_SIZE;
-       }
-#else /* CONFIG_X86_64 */
-       /*
-        * 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);
-                       list_for_each_entry(page, &pgd_list, lru) {
-                               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)));
-#endif
-}