diff options
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 986 |
1 files changed, 986 insertions, 0 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c new file mode 100644 index 0000000..621afb6 --- /dev/null +++ b/arch/x86/mm/fault.c @@ -0,0 +1,986 @@ +/* + * 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/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> + +/* + * Page fault error code bits + * bit 0 == 0 means no page found, 1 means protection fault + * bit 1 == 0 means read, 1 means write + * bit 2 == 0 means kernel, 1 means user-mode + * bit 3 == 1 means use of reserved bit detected + * bit 4 == 1 means fault was an instruction fetch + */ +#define PF_PROT (1<<0) +#define PF_WRITE (1<<1) +#define PF_USER (1<<2) +#define PF_RSVD (1<<3) +#define PF_INSTR (1<<4) + +static inline int notify_page_fault(struct pt_regs *regs) +{ +#ifdef CONFIG_KPROBES + int ret = 0; + + /* kprobe_running() needs smp_processor_id() */ +#ifdef CONFIG_X86_32 + if (!user_mode_vm(regs)) { +#else + if (!user_mode(regs)) { +#endif + preempt_disable(); + if (kprobe_running() && kprobe_fault_handler(regs, 14)) + ret = 1; + preempt_enable(); + } + + return ret; +#else + return 0; +#endif +} + +/* + * X86_32 + * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. + * Check that here and ignore it. + * + * X86_64 + * Sometimes the CPU reports invalid exceptions on prefetch. + * Check that here and ignore it. + * + * Opcode checker based on code by Richard Brunner + */ +static int is_prefetch(struct pt_regs *regs, unsigned long addr, + unsigned long error_code) +{ + unsigned char *instr; + int scan_more = 1; + int prefetch = 0; + unsigned char *max_instr; + +#ifdef CONFIG_X86_32 + if (!(__supported_pte_mask & _PAGE_NX)) + return 0; +#endif + + /* If it was a exec fault on NX page, ignore */ + 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 + +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; +} + +void do_invalid_op(struct pt_regs *, unsigned long); + +static int is_f00f_bug(struct pt_regs *regs, unsigned long address) +{ +#ifdef CONFIG_X86_F00F_BUG + unsigned long nr; + /* + * Pentium F0 0F C7 C8 bug workaround. + */ + if (boot_cpu_data.f00f_bug) { + nr = (address - idt_descr.address) >> 3; + + if (nr == 6) { + do_invalid_op(regs, 0); + return 1; + } + } +#endif + return 0; +} + +static void show_fault_oops(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ +#ifdef CONFIG_X86_32 + if (!oops_may_print()) + return; +#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"); +#ifdef CONFIG_X86_32 + printk(KERN_CONT " at %08lx\n", address); +#else + printk(KERN_CONT " at %016lx\n", address); +#endif + 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; + /* + * 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; + + /* + * 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|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( +#ifdef CONFIG_X86_32 + "%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx", +#else + "%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx", +#endif + task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, + tsk->comm, task_pid_nr(tsk), address, regs->ip, + regs->sp, error_code); + print_vma_addr(" in ", regs->ip); + printk("\n"); + } + + tsk->thread.cr2 = address; + /* Kernel addresses are always protection faults */ + tsk->thread.error_code = error_code | (address >= TASK_SIZE); + tsk->thread.trap_no = 14; + force_sig_info_fault(SIGSEGV, si_code, address, tsk); + return; + } + + if (is_f00f_bug(regs, address)) + return; + +no_context: + /* Are we prepared to handle this kernel fault? */ + if (fixup_exception(regs)) + return; + + /* + * X86_32 + * Valid to do another page fault here, because if this fault + * had been triggered by is_prefetch fixup_exception would have + * handled it. + * + * X86_64 + * Hall of shame of CPU/BIOS bugs. + */ + if (is_prefetch(regs, address, error_code)) + return; + + if (is_errata93(regs, address)) + return; + +/* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ +#ifdef CONFIG_X86_32 + bust_spinlocks(1); +#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 + /* + * 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); + list_for_each_entry(page, &pgd_list, lru) { + if (!vmalloc_sync_one(page_address(page), + address)) + break; + } + spin_unlock_irqrestore(&pgd_lock, flags); + if (!page) + set_bit(pgd_index(address), insync); + } + if (address == start && test_bit(pgd_index(address), insync)) + start = address + PGDIR_SIZE; + } +#else /* CONFIG_X86_64 */ + /* + * Note that races in the updates of insync and start aren't + * problematic: insync can only get set bits added, and updates to + * start are only improving performance (without affecting correctness + * if undone). + */ + static DECLARE_BITMAP(insync, PTRS_PER_PGD); + static unsigned long start = VMALLOC_START & PGDIR_MASK; + unsigned long address; + + for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) { + if (!test_bit(pgd_index(address), insync)) { + const pgd_t *pgd_ref = pgd_offset_k(address); + 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); + set_bit(pgd_index(address), insync); + } + if (address == start) + start = address + PGDIR_SIZE; + } + /* Check that there is no need to do the same for the modules area. */ + BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL)); + BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == + (__START_KERNEL & PGDIR_MASK))); +#endif +} |
