diff options
Diffstat (limited to 'arch/mips/mm/fault.c')
| -rw-r--r-- | arch/mips/mm/fault.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c new file mode 100644 index 00000000000..ec8077c74e9 --- /dev/null +++ b/arch/mips/mm/fault.c @@ -0,0 +1,236 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 1995 - 2000 by Ralf Baechle + */ +#include <linux/signal.h> +#include <linux/sched.h> +#include <linux/interrupt.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/vt_kern.h> /* For unblank_screen() */ +#include <linux/module.h> + +#include <asm/branch.h> +#include <asm/mmu_context.h> +#include <asm/system.h> +#include <asm/uaccess.h> +#include <asm/ptrace.h> + +/* + * 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 do_page_fault(struct pt_regs *regs, unsigned long write, + unsigned long address) +{ + struct vm_area_struct * vma = NULL; + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + const int field = sizeof(unsigned long) * 2; + siginfo_t info; + +#if 0 + printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", smp_processor_id(), + current->comm, current->pid, field, address, write, + field, regs->cp0_epc); +#endif + + 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. + */ + if (unlikely(address >= VMALLOC_START)) + goto vmalloc_fault; + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_atomic() || !mm) + goto bad_area_nosemaphore; + + 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 (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; + + if (write) { + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + } else { + 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 VM_FAULT_MINOR: + tsk->min_flt++; + break; + case VM_FAULT_MAJOR: + tsk->maj_flt++; + break; + case VM_FAULT_SIGBUS: + goto do_sigbus; + case VM_FAULT_OOM: + goto out_of_memory; + default: + BUG(); + } + + 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 (user_mode(regs)) { + tsk->thread.cp0_badvaddr = address; + tsk->thread.error_code = write; +#if 0 + printk("do_page_fault() #2: sending SIGSEGV to %s for " + "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", + tsk->comm, + write ? "write access to" : "read access from", + field, address, + field, (unsigned long) regs->cp0_epc, + field, (unsigned long) regs->regs[31]); +#endif + 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_exception(regs)) { + current->thread.cp0_baduaddr = address; + return; + } + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + + bust_spinlocks(1); + + printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " + "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", + smp_processor_id(), field, address, field, regs->cp0_epc, + field, regs->regs[31]); + die("Oops", regs); + +/* + * 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) { + yield(); + down_read(&mm->mmap_sem); + goto survive; + } + printk("VM: killing process %s\n", tsk->comm); + if (user_mode(regs)) + do_exit(SIGKILL); + goto no_context; + +do_sigbus: + up_read(&mm->mmap_sem); + + /* Kernel mode? Handle exceptions or die */ + if (!user_mode(regs)) + goto no_context; + + /* + * Send a sigbus, regardless of whether we were in kernel + * or user mode. + */ + tsk->thread.cp0_badvaddr = address; + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = BUS_ADRERR; + info.si_addr = (void *) address; + force_sig_info(SIGBUS, &info, tsk); + + 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 = (pgd_t *) pgd_current[smp_processor_id()] + offset; + 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_kernel(pmd_k, address); + if (!pte_present(*pte_k)) + goto no_context; + return; + } +} |