1 files changed, 579 insertions, 0 deletions

diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
new file mode 100644
index 000000000000..5724370475cc
--- /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 <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 = (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;
+}