Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9c89b008ca6ec2c1b75b1e9c698a0cc4dcbf5e4e
Commit:     9c89b008ca6ec2c1b75b1e9c698a0cc4dcbf5e4e
Parent:     4ec0f73f27cbcf728311d8da7994477c1bd4edbb
Author:     Thomas Gleixner <[EMAIL PROTECTED]>
AuthorDate: Thu Oct 11 11:16:19 2007 +0200
Committer:  Thomas Gleixner <[EMAIL PROTECTED]>
CommitDate: Thu Oct 11 11:16:19 2007 +0200

    x86_64: prepare shared mm/fault.c
    
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
 arch/x86_64/mm/Makefile   |    2 +-
 arch/x86_64/mm/fault.c    |  636 ---------------------------------------------
 arch/x86_64/mm/fault_64.c |  636 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 637 insertions(+), 637 deletions(-)

diff --git a/arch/x86_64/mm/Makefile b/arch/x86_64/mm/Makefile
index 019f589..2e20988 100644
--- a/arch/x86_64/mm/Makefile
+++ b/arch/x86_64/mm/Makefile
@@ -2,7 +2,7 @@
 # Makefile for the linux x86_64-specific parts of the memory manager.
 #
 
-obj-y   := init_64.o fault.o ioremap_64.o extable_64.o pageattr_64.o mmap_64.o
+obj-y   := init_64.o fault_64.o ioremap_64.o extable_64.o pageattr_64.o 
mmap_64.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
 obj-$(CONFIG_NUMA) += numa_64.o
 obj-$(CONFIG_K8_NUMA) += k8topology_64.o
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
deleted file mode 100644
index 54816ad..0000000
--- a/arch/x86_64/mm/fault.c
+++ /dev/null
@@ -1,636 +0,0 @@
-/*
- *  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/interrupt.h>
-#include <linux/init.h>
-#include <linux/tty.h>
-#include <linux/vt_kern.h>             /* For unblank_screen() */
-#include <linux/compiler.h>
-#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/pgalloc.h>
-#include <asm/smp.h>
-#include <asm/tlbflush.h>
-#include <asm/proto.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);
-
-/* 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);
-
-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);
-
-static inline int notify_page_fault(struct pt_regs *regs, long err)
-{
-       struct die_args args = {
-               .regs = regs,
-               .str = "page fault",
-               .err = err,
-               .trapnr = 14,
-               .signr = SIGSEGV
-       };
-       return atomic_notifier_call_chain(&notify_page_fault_chain,
-                                         DIE_PAGE_FAULT, &args);
-}
-
-/* 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 *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 (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 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 (probe_kernel_address(instr, opcode))
-                               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 probe_kernel_address((unsigned long *)p, dummy);
-} 
-
-void dump_pagetable(unsigned long address)
-{
-       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)) 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;
-} 
-
-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;
-}
-
-static int page_fault_trace;
-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.
- */
-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, fault;
-       unsigned long flags;
-       siginfo_t info;
-
-       tsk = current;
-       mm = tsk->mm;
-       prefetchw(&mm->mmap_sem);
-
-       /* get the address */
-       address = read_cr2();
-
-       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;
-               }
-               if (notify_page_fault(regs, error_code) == NOTIFY_STOP)
-                       return;
-               /*
-                * Don't take the mm semaphore here. If we fixup a prefetch
-                * fault we could otherwise deadlock.
-                */
-               goto bad_area_nosemaphore;
-       }
-
-       if (notify_page_fault(regs, error_code) == 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;
-
-       /*
-        * 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:
-       /* 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 | 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(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++;
-       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();
-
-               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 (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
-                   printk_ratelimit()) {
-                       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 (is_init(current)) {
-               yield();
-               goto again;
-       }
-       printk("VM: killing process %s\n", tsk->comm);
-       if (error_code & 4)
-               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;
-
-       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);
-LIST_HEAD(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);
-                       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)));
-}
-
-static int __init enable_pagefaulttrace(char *str)
-{
-       page_fault_trace = 1;
-       return 1;
-}
-__setup("pagefaulttrace", enable_pagefaulttrace);
diff --git a/arch/x86_64/mm/fault_64.c b/arch/x86_64/mm/fault_64.c
new file mode 100644
index 0000000..54816ad
--- /dev/null
+++ b/arch/x86_64/mm/fault_64.c
@@ -0,0 +1,636 @@
+/*
+ *  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/interrupt.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/vt_kern.h>             /* For unblank_screen() */
+#include <linux/compiler.h>
+#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/pgalloc.h>
+#include <asm/smp.h>
+#include <asm/tlbflush.h>
+#include <asm/proto.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);
+
+/* 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);
+
+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);
+
+static inline int notify_page_fault(struct pt_regs *regs, long err)
+{
+       struct die_args args = {
+               .regs = regs,
+               .str = "page fault",
+               .err = err,
+               .trapnr = 14,
+               .signr = SIGSEGV
+       };
+       return atomic_notifier_call_chain(&notify_page_fault_chain,
+                                         DIE_PAGE_FAULT, &args);
+}
+
+/* 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 *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 (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 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 (probe_kernel_address(instr, opcode))
+                               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 probe_kernel_address((unsigned long *)p, dummy);
+} 
+
+void dump_pagetable(unsigned long address)
+{
+       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)) 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;
+} 
+
+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;
+}
+
+static int page_fault_trace;
+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.
+ */
+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, fault;
+       unsigned long flags;
+       siginfo_t info;
+
+       tsk = current;
+       mm = tsk->mm;
+       prefetchw(&mm->mmap_sem);
+
+       /* get the address */
+       address = read_cr2();
+
+       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;
+               }
+               if (notify_page_fault(regs, error_code) == NOTIFY_STOP)
+                       return;
+               /*
+                * Don't take the mm semaphore here. If we fixup a prefetch
+                * fault we could otherwise deadlock.
+                */
+               goto bad_area_nosemaphore;
+       }
+
+       if (notify_page_fault(regs, error_code) == 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;
+
+       /*
+        * 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:
+       /* 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 | 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(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++;
+       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();
+
+               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 (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+                   printk_ratelimit()) {
+                       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 (is_init(current)) {
+               yield();
+               goto again;
+       }
+       printk("VM: killing process %s\n", tsk->comm);
+       if (error_code & 4)
+               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;
+
+       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);
+LIST_HEAD(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);
+                       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)));
+}
+
+static int __init enable_pagefaulttrace(char *str)
+{
+       page_fault_trace = 1;
+       return 1;
+}
+__setup("pagefaulttrace", enable_pagefaulttrace);
-
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