Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 *  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 <linux/kprobes.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)

#ifdef CONFIG_KPROBES

static inline int notify_page_fault(struct pt_regs *regs)

{

        int ret = 0;

        /* kprobe_running() needs smp_processor_id() */

        if (!user_mode(regs)) {

                preempt_disable();

                if (kprobe_running() && kprobe_fault_handler(regs, 14))

                        ret = 1;

                preempt_enable();

        }

        return ret;

}

#else

static inline int notify_page_fault(struct pt_regs *regs)

{

        return 0;

}

#endif

/* 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) || 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");

}

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;

}

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;

        /*

         * 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();

        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))

                        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))

                return;

        if (likely(regs->eflags & X86_EFLAGS_IF))

                local_irq_enable();

        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.  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->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 %lx rip %lx rsp %lx 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_global_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)));

}