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author | smh22@boulderdash.cl.cam.ac.uk <smh22@boulderdash.cl.cam.ac.uk> | 2002-11-20 12:02:17 +0000 |
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committer | smh22@boulderdash.cl.cam.ac.uk <smh22@boulderdash.cl.cam.ac.uk> | 2002-11-20 12:02:17 +0000 |
commit | 4676bbf96dc88e9a70607fa79b3c83febc5dc54b (patch) | |
tree | ea469343cb62cad40367c2ec3fec038405649a5c /xenolinux-2.4.16-sparse/arch/xeno/mm/fault.c | |
parent | 19e522da85965a058fe60ab74270dc6cdfc4e0b9 (diff) | |
download | xen-4676bbf96dc88e9a70607fa79b3c83febc5dc54b.tar.gz xen-4676bbf96dc88e9a70607fa79b3c83febc5dc54b.tar.bz2 xen-4676bbf96dc88e9a70607fa79b3c83febc5dc54b.zip |
bitkeeper revision 1.2 (3ddb79c9KusG02eh7i-uXkgY0IksKA)
Import changeset
Diffstat (limited to 'xenolinux-2.4.16-sparse/arch/xeno/mm/fault.c')
-rw-r--r-- | xenolinux-2.4.16-sparse/arch/xeno/mm/fault.c | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/xenolinux-2.4.16-sparse/arch/xeno/mm/fault.c b/xenolinux-2.4.16-sparse/arch/xeno/mm/fault.c new file mode 100644 index 0000000000..18e21674a9 --- /dev/null +++ b/xenolinux-2.4.16-sparse/arch/xeno/mm/fault.c @@ -0,0 +1,375 @@ +/* + * linux/arch/i386/mm/fault.c + * + * Copyright (C) 1995 Linus Torvalds + */ + +#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 <asm/system.h> +#include <asm/uaccess.h> +#include <asm/pgalloc.h> +#include <asm/hardirq.h> + +extern void die(const char *,struct pt_regs *,long); + +extern int console_loglevel; + +pgd_t *cur_pgd; + +/* + * Ugly, ugly, but the goto's result in better assembly.. + */ +int __verify_write(const void * addr, unsigned long size) +{ + struct vm_area_struct * vma; + unsigned long start = (unsigned long) addr; + + if (!size) + return 1; + + vma = find_vma(current->mm, start); + if (!vma) + goto bad_area; + if (vma->vm_start > start) + goto check_stack; + +good_area: + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + size--; + size += start & ~PAGE_MASK; + size >>= PAGE_SHIFT; + start &= PAGE_MASK; + + for (;;) { + survive: + { + int fault = handle_mm_fault(current->mm, vma, start, 1); + if (!fault) + goto bad_area; + if (fault < 0) + goto out_of_memory; + } + if (!size) + break; + size--; + start += PAGE_SIZE; + if (start < vma->vm_end) + continue; + vma = vma->vm_next; + if (!vma || vma->vm_start != start) + goto bad_area; + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area;; + } + return 1; + +check_stack: + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto bad_area; + if (expand_stack(vma, start) == 0) + goto good_area; + +bad_area: + return 0; + +out_of_memory: + if (current->pid == 1) { + current->policy |= SCHED_YIELD; + schedule(); + goto survive; + } + goto bad_area; +} + +extern spinlock_t timerlist_lock; + +/* + * Unlock any spinlocks which will prevent us from getting the + * message out (timerlist_lock is acquired through the + * console unblank code) + */ +void bust_spinlocks(int yes) +{ + spin_lock_init(&timerlist_lock); + if (yes) { + oops_in_progress = 1; + } else { + int loglevel_save = console_loglevel; +#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; + } +} + +void do_BUG(const char *file, int line) +{ + bust_spinlocks(1); + printk("kernel BUG at %s:%d!\n", file, line); +} + +/* + * 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 + */ +asmlinkage void do_page_fault(struct pt_regs *regs, + unsigned long error_code, + unsigned long address) +{ + struct task_struct *tsk = current; + struct mm_struct *mm; + struct vm_area_struct * vma; + unsigned long page; + unsigned long fixup; + int write; + siginfo_t info; + + /* Set the "privileged fault" bit to something sane. */ + error_code &= ~4; + error_code |= (regs->xcs & 2) << 1; + + /* + * 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 (address >= TASK_SIZE && !(error_code & 5)) + goto vmalloc_fault; + + mm = tsk->mm; + info.si_code = SEGV_MAPERR; + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_interrupt() || !mm) + goto no_context; + + down_read(&mm->mmap_sem); + + vma = find_vma(mm, address); + if (!vma) + goto bad_area; + if (vma->vm_start <= address) + goto good_area; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto bad_area; + if (error_code & 4) { + /* + * accessing the stack below %esp is always a bug. + * The "+ 32" is there due to some instructions (like + * pusha) doing post-decrement on the stack and that + * doesn't show up until later.. + */ + if (address + 32 < regs->esp) + 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; + } + + survive: + /* + * 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); + + /* User mode accesses just cause a SIGSEGV */ + if (error_code & 4) { + tsk->thread.cr2 = address; + tsk->thread.error_code = error_code; + tsk->thread.trap_no = 14; + info.si_signo = SIGSEGV; + info.si_errno = 0; + /* info.si_code has been set above */ + info.si_addr = (void *)address; + force_sig_info(SIGSEGV, &info, tsk); + return; + } + +no_context: + /* Are we prepared to handle this kernel fault? */ + if ((fixup = search_exception_table(regs->eip)) != 0) { + regs->eip = fixup; + return; + } + +/* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + + bust_spinlocks(1); + + 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 virtual address %08lx\n",address); + printk(" printing eip:\n"); + printk("%08lx\n", regs->eip); + page = ((unsigned long *) cur_pgd)[address >> 22]; + printk(KERN_ALERT "*pde = %08lx\n", page); + if (page & 1) { + page &= PAGE_MASK; + address &= 0x003ff000; + page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT]; + printk(KERN_ALERT "*pte = %08lx\n", page); + } + die("Oops", regs, error_code); + bust_spinlocks(0); + 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 (tsk->pid == 1) { + tsk->policy |= SCHED_YIELD; + schedule(); + down_read(&mm->mmap_sem); + goto survive; + } + 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); + + /* + * Send a sigbus, regardless of whether we were in kernel + * or user mode. + */ + 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 *)address; + force_sig_info(SIGBUS, &info, tsk); + + /* Kernel mode? Handle exceptions or die */ + if (!(error_code & 4)) + goto no_context; + return; + +vmalloc_fault: + { + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + * + * Do _not_ use "tsk" here. We might be inside + * an interrupt in the middle of a task switch.. + */ + int offset = __pgd_offset(address); + pgd_t *pgd, *pgd_k; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + + pgd = offset + cur_pgd; + pgd_k = init_mm.pgd + offset; + + if (!pgd_present(*pgd_k)) + goto no_context; + set_pgd(pgd, *pgd_k); + + pmd = pmd_offset(pgd, address); + pmd_k = pmd_offset(pgd_k, address); + if (!pmd_present(*pmd_k)) + goto no_context; + set_pmd(pmd, *pmd_k); + + pte_k = pte_offset(pmd_k, address); + if (!pte_present(*pte_k)) + goto no_context; + return; + } +} |