| /* |
| * 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/mmiotrace.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/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> |
| #include <asm/pgalloc.h> |
| #include <asm/smp.h> |
| #include <asm/tlbflush.h> |
| #include <asm/proto.h> |
| #include <asm-generic/sections.h> |
| #include <asm/traps.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 kmmio_fault(struct pt_regs *regs, unsigned long addr) |
| { |
| #ifdef CONFIG_MMIOTRACE_HOOKS |
| if (unlikely(is_kmmio_active())) |
| if (kmmio_handler(regs, addr) == 1) |
| return -1; |
| #endif |
| return 0; |
| } |
| |
| static inline int notify_page_fault(struct pt_regs *regs) |
| { |
| #ifdef CONFIG_KPROBES |
| int ret = 0; |
| |
| /* kprobe_running() needs smp_processor_id() */ |
| if (!user_mode_vm(regs)) { |
| 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; |
| |
| /* |
| * If it was a exec (instruction fetch) fault on NX page, then |
| * do not ignore the fault: |
| */ |
| if (error_code & PF_INSTR) |
| return 0; |
| |
| 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 |
| |
| static 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) || pud_large(*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; |
| } |
| |
| 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; |
| #endif |
| |
| #ifdef CONFIG_X86_PAE |
| if (error_code & PF_INSTR) { |
| unsigned 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 %p\n", (void *) address); |
| printk(KERN_ALERT "IP:"); |
| printk_address(regs->ip, 1); |
| dump_pagetable(address); |
| } |
| |
| #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 |
| |
| static int spurious_fault_check(unsigned long error_code, pte_t *pte) |
| { |
| if ((error_code & PF_WRITE) && !pte_write(*pte)) |
| return 0; |
| if ((error_code & PF_INSTR) && !pte_exec(*pte)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * Handle a spurious fault caused by a stale TLB entry. This allows |
| * us to lazily refresh the TLB when increasing the permissions of a |
| * kernel page (RO -> RW or NX -> X). Doing it eagerly is very |
| * expensive since that implies doing a full cross-processor TLB |
| * flush, even if no stale TLB entries exist on other processors. |
| * There are no security implications to leaving a stale TLB when |
| * increasing the permissions on a page. |
| */ |
| static int spurious_fault(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 & (PF_USER | PF_RSVD)) |
| 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; |
| |
| if (pud_large(*pud)) |
| return spurious_fault_check(error_code, (pte_t *) pud); |
| |
| pmd = pmd_offset(pud, address); |
| if (!pmd_present(*pmd)) |
| return 0; |
| |
| if (pmd_large(*pmd)) |
| return spurious_fault_check(error_code, (pte_t *) pmd); |
| |
| pte = pte_offset_kernel(pmd, address); |
| if (!pte_present(*pte)) |
| return 0; |
| |
| return spurious_fault_check(error_code, pte); |
| } |
| |
| /* |
| * 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; |
| |
| /* Make sure we are in vmalloc area */ |
| if (!(address >= VMALLOC_START && address < VMALLOC_END)) |
| return -1; |
| |
| /* |
| * 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; |
| |
| /* Make sure we are in vmalloc area */ |
| if (!(address >= VMALLOC_START && address < VMALLOC_END)) |
| return -1; |
| |
| /* 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; |
| if (unlikely(kmmio_fault(regs, address))) |
| 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)) { |
| #else |
| if (unlikely(address >= TASK_SIZE64)) { |
| #endif |
| if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) && |
| vmalloc_fault(address) >= 0) |
| return; |
| |
| /* Can handle a stale RO->RW TLB */ |
| if (spurious_fault(address, error_code)) |
| return; |
| |
| /* |
| * Don't take the mm semaphore here. If we fixup a prefetch |
| * fault we could otherwise deadlock. |
| */ |
| goto bad_area_nosemaphore; |
| } |
| |
| |
| #ifdef CONFIG_X86_32 |
| /* 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 | X86_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 (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; |
| if (vma->vm_start <= address) |
| 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( |
| "%s%s[%d]: segfault at %lx ip %p sp %p error %lx", |
| task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, |
| tsk->comm, task_pid_nr(tsk), address, |
| (void *) regs->ip, (void *) 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); |
| #else |
| flags = oops_begin(); |
| #endif |
| |
| show_fault_oops(regs, error_code, address); |
| |
| tsk->thread.cr2 = address; |
| tsk->thread.trap_no = 14; |
| tsk->thread.error_code = error_code; |
| |
| #ifdef CONFIG_X86_32 |
| die("Oops", regs, error_code); |
| bust_spinlocks(0); |
| do_exit(SIGKILL); |
| #else |
| 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); |
| if (is_global_init(tsk)) { |
| yield(); |
| #ifdef CONFIG_X86_32 |
| down_read(&mm->mmap_sem); |
| goto survive; |
| #else |
| 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); |
| } |
| |
| DEFINE_SPINLOCK(pgd_lock); |
| LIST_HEAD(pgd_list); |
| |
| void vmalloc_sync_all(void) |
| { |
| #ifdef CONFIG_X86_32 |
| unsigned long start = VMALLOC_START & PGDIR_MASK; |
| unsigned long address; |
| |
| if (SHARED_KERNEL_PMD) |
| return; |
| |
| BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK); |
| for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) { |
| unsigned long flags; |
| struct page *page; |
| |
| spin_lock_irqsave(&pgd_lock, flags); |
| list_for_each_entry(page, &pgd_list, lru) { |
| if (!vmalloc_sync_one(page_address(page), |
| address)) |
| break; |
| } |
| spin_unlock_irqrestore(&pgd_lock, flags); |
| } |
| #else /* CONFIG_X86_64 */ |
| unsigned long start = VMALLOC_START & PGDIR_MASK; |
| unsigned long address; |
| |
| for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) { |
| const pgd_t *pgd_ref = pgd_offset_k(address); |
| unsigned long flags; |
| struct page *page; |
| |
| if (pgd_none(*pgd_ref)) |
| continue; |
| spin_lock_irqsave(&pgd_lock, flags); |
| 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_irqrestore(&pgd_lock, flags); |
| } |
| #endif |
| } |