+++ /dev/null
-/*
- * 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/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>
-
-extern void die(const char *,struct pt_regs *,long);
-
-static 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);
-}
-EXPORT_SYMBOL_GPL(register_page_fault_notifier);
-
-int unregister_page_fault_notifier(struct notifier_block *nb)
-{
- return atomic_notifier_chain_unregister(¬ify_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(¬ify_page_fault_chain,
- DIE_PAGE_FAULT, &args);
-}
-
-/*
- * 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 = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg;
-
- /* By far the most common cases. */
- if (likely(SEGMENT_IS_FLAT_CODE(seg)))
- 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 char *instr = (unsigned char *)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 > (unsigned char *)limit)
- break;
- 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. */
- 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 > (unsigned char *)limit)
- break;
- if (probe_kernel_address(instr, opcode))
- 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);
-
-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;
-}
-
-/*
- * 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;
-}
-
-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.
- *
- * 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;
- int fault;
-
- /* get the address */
- address = read_cr2();
-
- 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)) {
- if (!(error_code & 0x0000000d) && 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;
-
- /* 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 */
- /* 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 | VM_WRITE)))
- 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.
- */
- 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++;
-
- /*
- * 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) {
- /*
- * 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 (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
- printk_ratelimit()) {
- printk("%s%s[%d]: segfault at %08lx eip %08lx "
- "esp %08lx error %lx\n",
- tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
- tsk->comm, tsk->pid, address, regs->eip,
- regs->esp, 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;
- 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()) {
- __typeof__(pte_val(__pte(0))) page;
-
-#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);
-
- page = read_cr3();
- page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
-#ifdef CONFIG_X86_PAE
- printk(KERN_ALERT "*pdpt = %016Lx\n", 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_ALERT "*pde = %016Lx\n", page);
- page &= ~_PAGE_NX;
- }
-#else
- printk(KERN_ALERT "*pde = %08lx\n", 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_MASK;
- page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
- & (PTRS_PER_PTE - 1)];
- printk(KERN_ALERT "*pte = %0*Lx\n", sizeof(page)*2, (u64)page);
- }
- }
-
- 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 (is_init(tsk)) {
- 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);
-}
-
-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;
-
- 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;
- }
-}
projects / karo-tx-linux.git / blobdiff