diff options
Diffstat (limited to 'linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c')
| -rw-r--r-- | linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c | 769 |
1 files changed, 0 insertions, 769 deletions
diff --git a/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c b/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c deleted file mode 100644 index 78639201bc..0000000000 --- a/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c +++ /dev/null @@ -1,769 +0,0 @@ -/* - * linux/arch/i386/mm/fault.c - * - * 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/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/highmem.h> -#include <linux/module.h> -#include <linux/kprobes.h> - -#include <asm/system.h> -#include <asm/uaccess.h> -#include <asm/desc.h> -#include <asm/kdebug.h> - -extern void die(const char *,struct pt_regs *,long); - -#ifdef CONFIG_KPROBES -ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain); -int register_page_fault_notifier(struct notifier_block *nb) -{ - vmalloc_sync_all(); - return atomic_notifier_chain_register(¬ify_page_fault_chain, nb); -} - -int unregister_page_fault_notifier(struct notifier_block *nb) -{ - return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb); -} - -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(¬ify_page_fault_chain, val, &args); -} -#else -static inline int notify_page_fault(enum die_val val, const char *str, - struct pt_regs *regs, long err, int trap, int sig) -{ - return NOTIFY_DONE; -} -#endif - - -/* - * Unlock any spinlocks which will prevent us from getting the - * message out - */ -void bust_spinlocks(int yes) -{ - int loglevel_save = console_loglevel; - - if (yes) { - oops_in_progress = 1; - return; - } -#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; -} - -/* - * Return EIP plus the CS segment base. The segment limit is also - * adjusted, clamped to the kernel/user address space (whichever is - * appropriate), and returned in *eip_limit. - * - * The segment is checked, because it might have been changed by another - * task between the original faulting instruction and here. - * - * If CS is no longer a valid code segment, or if EIP is beyond the - * limit, or if it is a kernel address when CS is not a kernel segment, - * then the returned value will be greater than *eip_limit. - * - * This is slow, but is very rarely executed. - */ -static inline unsigned long get_segment_eip(struct pt_regs *regs, - unsigned long *eip_limit) -{ - unsigned long eip = regs->eip; - unsigned seg = regs->xcs & 0xffff; - u32 seg_ar, seg_limit, base, *desc; - - /* Unlikely, but must come before segment checks. */ - if (unlikely(regs->eflags & VM_MASK)) { - base = seg << 4; - *eip_limit = base + 0xffff; - return base + (eip & 0xffff); - } - - /* The standard kernel/user address space limit. */ - *eip_limit = (seg & 2) ? USER_DS.seg : KERNEL_DS.seg; - - /* By far the most common cases. */ - if (likely(seg == __USER_CS || seg == GET_KERNEL_CS())) - return eip; - - /* Check the segment exists, is within the current LDT/GDT size, - that kernel/user (ring 0..3) has the appropriate privilege, - that it's a code segment, and get the limit. */ - __asm__ ("larl %3,%0; lsll %3,%1" - : "=&r" (seg_ar), "=r" (seg_limit) : "0" (0), "rm" (seg)); - if ((~seg_ar & 0x9800) || eip > seg_limit) { - *eip_limit = 0; - return 1; /* So that returned eip > *eip_limit. */ - } - - /* Get the GDT/LDT descriptor base. - When you look for races in this code remember that - LDT and other horrors are only used in user space. */ - if (seg & (1<<2)) { - /* Must lock the LDT while reading it. */ - down(¤t->mm->context.sem); - desc = current->mm->context.ldt; - desc = (void *)desc + (seg & ~7); - } else { - /* Must disable preemption while reading the GDT. */ - desc = (u32 *)get_cpu_gdt_table(get_cpu()); - desc = (void *)desc + (seg & ~7); - } - - /* Decode the code segment base from the descriptor */ - base = get_desc_base((unsigned long *)desc); - - if (seg & (1<<2)) { - up(¤t->mm->context.sem); - } else - put_cpu(); - - /* Adjust EIP and segment limit, and clamp at the kernel limit. - It's legitimate for segments to wrap at 0xffffffff. */ - seg_limit += base; - if (seg_limit < *eip_limit && seg_limit >= base) - *eip_limit = seg_limit; - return eip + base; -} - -/* - * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. - * Check that here and ignore it. - */ -static int __is_prefetch(struct pt_regs *regs, unsigned long addr) -{ - unsigned long limit; - unsigned long instr = get_segment_eip (regs, &limit); - int scan_more = 1; - int prefetch = 0; - int i; - - for (i = 0; scan_more && i < 15; i++) { - unsigned char opcode; - unsigned char instr_hi; - unsigned char instr_lo; - - if (instr > limit) - break; - if (__get_user(opcode, (unsigned 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. */ - scan_more = ((instr_lo & 7) == 0x6); - 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 */ - scan_more = !instr_lo || (instr_lo>>1) == 1; - break; - case 0x00: - /* Prefetch instruction is 0x0F0D or 0x0F18 */ - scan_more = 0; - if (instr > limit) - break; - if (__get_user(opcode, (unsigned char __user *) instr)) - break; - prefetch = (instr_lo == 0xF) && - (opcode == 0x0D || opcode == 0x18); - break; - default: - scan_more = 0; - break; - } - } - return prefetch; -} - -static inline int is_prefetch(struct pt_regs *regs, unsigned long addr, - unsigned long error_code) -{ - 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 & 16)) - return 0; - return __is_prefetch(regs, addr); - } - return 0; -} - -static noinline 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); -} - -fastcall void do_invalid_op(struct pt_regs *, unsigned long); - -#ifdef CONFIG_X86_PAE -static void dump_fault_path(unsigned long address) -{ - unsigned long *p, page; - unsigned long mfn; - - page = read_cr3(); - p = (unsigned long *)__va(page); - p += (address >> 30) * 2; - printk(KERN_ALERT "%08lx -> *pde = %08lx:%08lx\n", page, p[1], p[0]); - if (p[0] & 1) { - mfn = (p[0] >> PAGE_SHIFT) | (p[1] << 20); - page = mfn_to_pfn(mfn) << PAGE_SHIFT; - p = (unsigned long *)__va(page); - address &= 0x3fffffff; - p += (address >> 21) * 2; - printk(KERN_ALERT "%08lx -> *pme = %08lx:%08lx\n", - page, p[1], p[0]); - mfn = (p[0] >> PAGE_SHIFT) | (p[1] << 20); -#ifdef CONFIG_HIGHPTE - if (mfn_to_pfn(mfn) >= highstart_pfn) - return; -#endif - if (p[0] & 1) { - page = mfn_to_pfn(mfn) << PAGE_SHIFT; - p = (unsigned long *) __va(page); - address &= 0x001fffff; - p += (address >> 12) * 2; - printk(KERN_ALERT "%08lx -> *pte = %08lx:%08lx\n", - page, p[1], p[0]); - } - } -} -#else -static void dump_fault_path(unsigned long address) -{ - unsigned long page; - - page = read_cr3(); - page = ((unsigned long *) __va(page))[address >> 22]; - if (oops_may_print()) - printk(KERN_ALERT "*pde = ma %08lx pa %08lx\n", page, - machine_to_phys(page)); - /* - * We must not directly access the pte in the highpte - * case if the page table is located in highmem. - * And lets rather not kmap-atomic the pte, just in case - * it's allocated already. - */ -#ifdef CONFIG_HIGHPTE - if ((page >> PAGE_SHIFT) >= highstart_pfn) - return; -#endif - if ((page & 1) && oops_may_print()) { - page &= PAGE_MASK; - address &= 0x003ff000; - page = machine_to_phys(page); - page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT]; - printk(KERN_ALERT "*pte = ma %08lx pa %08lx\n", page, - machine_to_phys(page)); - } -} -#endif - -static int spurious_fault(struct pt_regs *regs, - unsigned long address, - unsigned long error_code) -{ - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; - pte_t *pte; - - /* Reserved-bit violation or user access to kernel space? */ - if (error_code & 0x0c) - return 0; - - pgd = init_mm.pgd + pgd_index(address); - if (!pgd_present(*pgd)) - return 0; - - pud = pud_offset(pgd, address); - if (!pud_present(*pud)) - return 0; - - pmd = pmd_offset(pud, address); - if (!pmd_present(*pmd)) - return 0; - - pte = pte_offset_kernel(pmd, address); - if (!pte_present(*pte)) - return 0; - if ((error_code & 0x02) && !pte_write(*pte)) - return 0; -#ifdef CONFIG_X86_PAE - if ((error_code & 0x10) && (pte_val(*pte) & _PAGE_NX)) - return 0; -#endif - - return 1; -} - -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)) -#ifndef CONFIG_XEN - set_pmd(pmd, *pmd_k); -#else - /* - * When running on Xen we must launder *pmd_k through - * pmd_val() to ensure that _PAGE_PRESENT is correctly set. - */ - set_pmd(pmd, __pmd(pmd_val(*pmd_k))); -#endif - else - BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); - return pmd_k; -} - -/* - * Handle a fault on the vmalloc or module mapping area - * - * This assumes no large pages in there. - */ -static inline int vmalloc_fault(unsigned long address) -{ - 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; -} - -/* - * This routine handles page faults. It determines the address, - * and the problem, and then passes it off to one of the appropriate - * routines. - * - * error_code: - * bit 0 == 0 means no page found, 1 means protection fault - * bit 1 == 0 means read, 1 means write - * 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 - */ -fastcall 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; - - /* get the address */ - address = read_cr2(); - - /* Set the "privileged fault" bit to something sane. */ - error_code &= ~4; - error_code |= (regs->xcs & 2) << 1; - if (regs->eflags & X86_EFLAGS_VM) - error_code |= 4; - - tsk = current; - - 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_SIZE)) { -#ifdef CONFIG_XEN - /* Faults in hypervisor area can never be patched up. */ - if (address >= hypervisor_virt_start) - goto bad_area_nosemaphore; -#endif - if (!(error_code & 0x0000000d) && vmalloc_fault(address) >= 0) - return; - /* Can take a spurious fault if mapping changes R/O -> R/W. */ - if (spurious_fault(regs, address, error_code)) - return; - 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; - } - - if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, - SIGSEGV) == NOTIFY_STOP) - return; - - /* It's safe to allow irq's after cr2 has been saved and the vmalloc - fault has been handled. */ - if (regs->eflags & (X86_EFLAGS_IF|VM_MASK)) - local_irq_enable(); - - mm = tsk->mm; - - /* - * If we're in an interrupt, have no user context or are running in an - * atomic region then we must not take the fault.. - */ - if (in_atomic() || !mm) - goto bad_area_nosemaphore; - - /* 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 & 4) == 0 && - !search_exception_tables(regs->eip)) - goto bad_area_nosemaphore; - down_read(&mm->mmap_sem); - } - - vma = find_vma(mm, address); - if (!vma) - goto bad_area; - if (vma->vm_start <= address) - goto good_area; - if (!(vma->vm_flags & VM_GROWSDOWN)) - goto bad_area; - if (error_code & 4) { - /* - * Accessing the stack below %esp is always a bug. - * The large cushion allows instructions like enter - * and pusha to work. ("enter $65535,$31" pushes - * 32 pointers and then decrements %esp by 65535.) - */ - if (address + 65536 + 32 * sizeof(unsigned long) < regs->esp) - 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 & 3) { - default: /* 3: write, present */ -#ifdef TEST_VERIFY_AREA - if (regs->cs == GET_KERNEL_CS()) - printk("WP fault at %08lx\n", regs->eip); -#endif - /* fall through */ - case 2: /* write, not present */ - if (!(vma->vm_flags & VM_WRITE)) - goto bad_area; - write++; - break; - case 1: /* read, present */ - goto bad_area; - case 0: /* read, not present */ - if (!(vma->vm_flags & (VM_READ | VM_EXEC))) - goto bad_area; - } - - survive: - /* - * 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; - case VM_FAULT_OOM: - goto out_of_memory; - default: - BUG(); - } - - /* - * Did it hit the DOS screen memory VA from vm86 mode? - */ - if (regs->eflags & VM_MASK) { - unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT; - if (bit < 32) - tsk->thread.screen_bitmap |= 1 << bit; - } - 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 & 4) { - /* - * Valid to do another page fault here because this one came - * from user space. - */ - if (is_prefetch(regs, address, error_code)) - return; - - 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; - } - -#ifdef CONFIG_X86_F00F_BUG - /* - * Pentium F0 0F C7 C8 bug workaround. - */ - if (boot_cpu_data.f00f_bug) { - unsigned long nr; - - nr = (address - idt_descr.address) >> 3; - - if (nr == 6) { - do_invalid_op(regs, 0); - return; - } - } -#endif - -no_context: - /* Are we prepared to handle this kernel fault? */ - if (fixup_exception(regs)) - return; - - /* - * Valid to do another page fault here, because if this fault - * had been triggered by is_prefetch fixup_exception would have - * handled it. - */ - if (is_prefetch(regs, address, error_code)) - return; - -/* - * Oops. The kernel tried to access some bad page. We'll have to - * terminate things with extreme prejudice. - */ - - bust_spinlocks(1); - - if (oops_may_print()) { - #ifdef CONFIG_X86_PAE - if (error_code & 16) { - pte_t *pte = lookup_address(address); - - if (pte && pte_present(*pte) && !pte_exec_kernel(*pte)) - printk(KERN_CRIT "kernel tried to execute " - "NX-protected page - exploit attempt? " - "(uid: %d)\n", current->uid); - } - #endif - if (address < PAGE_SIZE) - printk(KERN_ALERT "BUG: unable to handle kernel NULL " - "pointer dereference"); - else - printk(KERN_ALERT "BUG: unable to handle kernel paging" - " request"); - printk(" at virtual address %08lx\n",address); - printk(KERN_ALERT " printing eip:\n"); - printk("%08lx\n", regs->eip); - } - dump_fault_path(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); - -/* - * 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 (tsk->pid == 1) { - yield(); - down_read(&mm->mmap_sem); - goto survive; - } - 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 & 4)) - goto no_context; - - /* User space => ok to do another page fault */ - if (is_prefetch(regs, address, error_code)) - return; - - tsk->thread.cr2 = address; - tsk->thread.error_code = error_code; - tsk->thread.trap_no = 14; - force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk); -} - -#if !HAVE_SHARED_KERNEL_PMD -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 = TASK_SIZE; - unsigned long address; - - 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; - } -} -#endif |