diff options
Diffstat (limited to 'arch/x86_64/mm/fault_64.c')
| -rw-r--r-- | arch/x86_64/mm/fault_64.c | 636 |
1 files changed, 0 insertions, 636 deletions
diff --git a/arch/x86_64/mm/fault_64.c b/arch/x86_64/mm/fault_64.c deleted file mode 100644 index 54816adb8e9..00000000000 --- a/arch/x86_64/mm/fault_64.c +++ /dev/null @@ -1,636 +0,0 @@ -/* - * linux/arch/x86-64/mm/fault.c - * - * 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/vmalloc.h> -#include <linux/module.h> -#include <linux/kprobes.h> -#include <linux/uaccess.h> -#include <linux/kdebug.h> - -#include <asm/system.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 */ -#define PF_PROT (1<<0) /* or no page found */ -#define PF_WRITE (1<<1) -#define PF_USER (1<<2) -#define PF_RSVD (1<<3) -#define PF_INSTR (1<<4) - -static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain); - -/* Hook to register for page fault notifications */ -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); -} - -/* 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 & PF_INSTR) - return 0; - - instr = (unsigned char __user *)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 (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 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 (probe_kernel_address(instr, opcode)) - 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 probe_kernel_address((unsigned long *)p, dummy); -} - -void dump_pagetable(unsigned long address) -{ - 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)) 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; -} - -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; - __die("Bad pagetable", regs, error_code); - oops_end(flags); - do_exit(SIGKILL); -} - -/* - * Handle a fault on the vmalloc 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); - 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; -} - -static int page_fault_trace; -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. - */ -asmlinkage 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; - const struct exception_table_entry *fixup; - int write, fault; - unsigned long flags; - siginfo_t info; - - tsk = current; - mm = tsk->mm; - prefetchw(&mm->mmap_sem); - - /* get the address */ - address = read_cr2(); - - 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 & 9) == 0. - */ - if (unlikely(address >= TASK_SIZE64)) { - /* - * Don't check for the module range here: its PML4 - * is always initialized because it's shared with the main - * kernel text. Only vmalloc may need PML4 syncups. - */ - if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) && - ((address >= VMALLOC_START && address < VMALLOC_END))) { - if (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; - - 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); - - if (unlikely(error_code & PF_RSVD)) - 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; - - /* - * 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: - /* 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 & PF_USER) == 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) { - /* Allow userspace just enough access below the stack pointer - * to let the 'enter' instruction work. - */ - if (address + 65536 + 32 * sizeof(unsigned long) < 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 & (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; - } - - /* - * 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++; - 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(); - - 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 (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && - printk_ratelimit()) { - 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. - */ - - flags = 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); - dump_pagetable(address); - tsk->thread.cr2 = address; - tsk->thread.trap_no = 14; - tsk->thread.error_code = error_code; - __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(flags); - 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(current)) { - yield(); - goto again; - } - printk("VM: killing process %s\n", tsk->comm); - if (error_code & 4) - 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; - - 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; -} - -DEFINE_SPINLOCK(pgd_lock); -LIST_HEAD(pgd_list); - -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 = 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); - struct page *page; - - if (pgd_none(*pgd_ref)) - continue; - spin_lock(&pgd_lock); - 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(&pgd_lock); - 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))); -} - -static int __init enable_pagefaulttrace(char *str) -{ - page_fault_trace = 1; - return 1; -} -__setup("pagefaulttrace", enable_pagefaulttrace); |