From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- arch/x86_64/mm/fault.c | 579 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 579 insertions(+) create mode 100644 arch/x86_64/mm/fault.c (limited to 'arch/x86_64/mm/fault.c') diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c new file mode 100644 index 0000000..5724370 --- /dev/null +++ b/arch/x86_64/mm/fault.c @@ -0,0 +1,579 @@ +/* + * linux/arch/x86-64/mm/fault.c + * + * Copyright (C) 1995 Linus Torvalds + * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include /* For unblank_screen() */ +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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 = (unsigned char *)(regs->rip); + int scan_more = 1; + int prefetch = 0; + unsigned char *max_instr = instr + 15; + + /* If it was a exec fault ignore */ + if (error_code & (1<<4)) + return 0; + + /* Code segments in LDT could have a non zero base. Don't check + when that's possible */ + if (regs->cs & (1<<2)) + return 0; + + if ((regs->cs & 3) != 0 && regs->rip >= 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 = ((regs->cs & 3) == 0) || (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 + */ +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); + if (!pte_present(*pte) || pte_page(*pte) != pte_page(*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_SIZE)) { + if (!(error_code & 5)) { + 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: + +#ifdef CONFIG_IA32_EMULATION + /* 32bit vsyscall. map on demand. */ + if (test_thread_flag(TIF_IA32) && + address >= VSYSCALL32_BASE && address < VSYSCALL32_END) { + if (map_syscall32(mm, address) < 0) + goto out_of_memory2; + return; + } +#endif + + /* 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); +out_of_memory2: + 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; +} -- cgit v1.1