| /* |
| * linux/arch/x86-64/mm/fault.c |
| * |
| * Copyright (C) 1995 Linus Torvalds |
| * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs. |
| */ |
| |
| #include <linux/config.h> |
| #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/compiler.h> |
| #include <linux/module.h> |
| #include <linux/kprobes.h> |
| |
| #include <asm/system.h> |
| #include <asm/uaccess.h> |
| #include <asm/pgalloc.h> |
| #include <asm/smp.h> |
| #include <asm/tlbflush.h> |
| #include <asm/proto.h> |
| #include <asm/kdebug.h> |
| #include <asm-generic/sections.h> |
| #include <asm/kdebug.h> |
| |
| void bust_spinlocks(int yes) |
| { |
| int loglevel_save = console_loglevel; |
| if (yes) { |
| oops_in_progress = 1; |
| } else { |
| #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; |
| } |
| } |
| |
| /* 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 & (1<<4)) |
| return 0; |
| |
| instr = (unsigned char *)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 (__get_user(opcode, 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. 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 (__get_user(opcode, instr)) |
| 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 __get_user(dummy, (unsigned long *)p); |
| } |
| |
| void dump_pagetable(unsigned long address) |
| { |
| pgd_t *pgd; |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *pte; |
| |
| asm("movq %%cr3,%0" : "=r" (pgd)); |
| |
| pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); |
| pgd += pgd_index(address); |
| printk("PGD %lx ", pgd_val(*pgd)); |
| if (bad_address(pgd)) goto bad; |
| if (!pgd_present(*pgd)) goto ret; |
| |
| pud = __pud_offset_k((pud_t *)pgd_page(*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; |
| } |
| |
| int unhandled_signal(struct task_struct *tsk, int sig) |
| { |
| if (tsk->pid == 1) |
| return 1; |
| /* Warn for strace, but not for gdb */ |
| if (!test_ti_thread_flag(tsk->thread_info, TIF_SYSCALL_TRACE) && |
| (tsk->ptrace & PT_PTRACED)) |
| return 0; |
| return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) || |
| (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL); |
| } |
| |
| static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, |
| unsigned long error_code) |
| { |
| oops_begin(); |
| printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", |
| current->comm, address); |
| dump_pagetable(address); |
| __die("Bad pagetable", regs, error_code); |
| oops_end(); |
| do_exit(SIGKILL); |
| } |
| |
| /* |
| * Handle a fault on the vmalloc or module mapping 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); |
| |
| /* 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(*pud) != pud_page(*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(); |
| __flush_tlb_all(); |
| return 0; |
| } |
| |
| int page_fault_trace = 0; |
| int exception_trace = 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 fault was an instruction fetch |
| */ |
| asmlinkage void 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; |
| siginfo_t info; |
| |
| #ifdef CONFIG_CHECKING |
| { |
| unsigned long gs; |
| struct x8664_pda *pda = cpu_pda + stack_smp_processor_id(); |
| rdmsrl(MSR_GS_BASE, gs); |
| if (gs != (unsigned long)pda) { |
| wrmsrl(MSR_GS_BASE, pda); |
| printk("page_fault: wrong gs %lx expected %p\n", gs, pda); |
| } |
| } |
| #endif |
| |
| /* get the address */ |
| __asm__("movq %%cr2,%0":"=r" (address)); |
| if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, |
| SIGSEGV) == 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); |
| |
| tsk = current; |
| mm = tsk->mm; |
| 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 & 1) == 0. |
| */ |
| if (unlikely(address >= TASK_SIZE64)) { |
| if (!(error_code & 5) && |
| ((address >= VMALLOC_START && address < VMALLOC_END) || |
| (address >= MODULES_VADDR && address < MODULES_END))) { |
| if (vmalloc_fault(address) < 0) |
| goto bad_area_nosemaphore; |
| return; |
| } |
| /* |
| * Don't take the mm semaphore here. If we fixup a prefetch |
| * fault we could otherwise deadlock. |
| */ |
| goto bad_area_nosemaphore; |
| } |
| |
| if (unlikely(error_code & (1 << 3))) |
| 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; |
| |
| 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 occuring 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->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) { |
| // XXX: align red zone size with ABI |
| if (address + 128 < 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 & 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))) |
| 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. |
| */ |
| switch (handle_mm_fault(mm, vma, address, write)) { |
| case 1: |
| tsk->min_flt++; |
| break; |
| case 2: |
| tsk->maj_flt++; |
| break; |
| case 0: |
| goto do_sigbus; |
| default: |
| goto out_of_memory; |
| } |
| |
| 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) { |
| 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 (exception_trace && unhandled_signal(tsk, SIGSEGV)) { |
| 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. |
| */ |
| |
| 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); |
| printk("\n"); |
| dump_pagetable(address); |
| __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(); |
| 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 (current->pid == 1) { |
| yield(); |
| goto again; |
| } |
| 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; |
| |
| 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; |
| } |