/* MN10300 MMU Fault handler * * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd. * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Modified by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #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/vt_kern.h> /* For unblank_screen() */ #include <asm/system.h> #include <asm/uaccess.h> #include <asm/pgalloc.h> #include <asm/hardirq.h> #include <asm/gdb-stub.h> #include <asm/cpu-regs.h> /* * Unlock any spinlocks which will prevent us from getting the * message out */ void bust_spinlocks(int yes) { if (yes) { oops_in_progress = 1; #ifdef CONFIG_SMP /* Many serial drivers do __global_cli() */ global_irq_lock = 0; #endif } 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(KERN_EMERG "------------[ cut here ]------------\n"); printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line); } #if 0 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address) { pgd_t *pgd; pmd_t *pmd; pte_t *pte; pgd = pgdir + __pgd_offset(address); printk(KERN_DEBUG "pgd entry %p: %016Lx\n", pgd, (long long) pgd_val(*pgd)); if (!pgd_present(*pgd)) { printk(KERN_DEBUG "... pgd not present!\n"); return; } pmd = pmd_offset(pgd, address); printk(KERN_DEBUG "pmd entry %p: %016Lx\n", pmd, (long long)pmd_val(*pmd)); if (!pmd_present(*pmd)) { printk(KERN_DEBUG "... pmd not present!\n"); return; } pte = pte_offset(pmd, address); printk(KERN_DEBUG "pte entry %p: %016Lx\n", pte, (long long) pte_val(*pte)); if (!pte_present(*pte)) printk(KERN_DEBUG "... pte not present!\n"); } #endif asmlinkage void monitor_signal(struct pt_regs *); /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. * * fault_code: * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate * - MSW: 0 if data access, 1 if instruction access * - bit 0: TLB miss flag * - bit 1: initial write * - bit 2: page invalid * - bit 3: protection violation * - bit 4: accessor (0=user 1=kernel) * - bit 5: 0=read 1=write * - bit 6-8: page protection spec * - bit 9: illegal address * - bit 16: 0=data 1=ins * */ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code, unsigned long address) { struct vm_area_struct *vma; struct task_struct *tsk; struct mm_struct *mm; unsigned long page; siginfo_t info; int write, fault; #ifdef CONFIG_GDBSTUB /* handle GDB stub causing a fault */ if (gdbstub_busy) { gdbstub_exception(regs, TBR & TBR_INT_CODE); return; } #endif #if 0 printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n", regs, fault_code & 0x10000 ? "ins" : "data", fault_code & 0xffff, address); #endif tsk = current; /* * 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 * and that the fault was a page not present (invalid) error */ if (address >= VMALLOC_START && address < VMALLOC_END && (fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR && (fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL ) 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_atomic() || !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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) { /* accessing the stack below the stack pointer is always a * bug */ if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) { #if 0 printk(KERN_WARNING "[%d] ### Access below stack @%lx (sp=%lx)\n", current->pid, address, regs->sp); printk(KERN_WARNING "vma [%08x - %08x]\n", vma->vm_start, vma->vm_end); show_registers(regs); printk(KERN_WARNING "[%d] ### Code: [%08lx]" " %02x %02x %02x %02x %02x %02x %02x %02x\n", current->pid, regs->pc, ((u8 *) regs->pc)[0], ((u8 *) regs->pc)[1], ((u8 *) regs->pc)[2], ((u8 *) regs->pc)[3], ((u8 *) regs->pc)[4], ((u8 *) regs->pc)[5], ((u8 *) regs->pc)[6], ((u8 *) regs->pc)[7] ); #endif 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 (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) { default: /* 3: write, present */ case MMUFCR_xFC_TYPE_WRITE: #ifdef TEST_VERIFY_AREA if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR) printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc); #endif /* write to absent page */ case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE: if (!(vma->vm_flags & VM_WRITE)) goto bad_area; write++; break; /* read from protected page */ case MMUFCR_xFC_TYPE_READ: goto bad_area; /* read from absent page present */ case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ: if (!(vma->vm_flags & (VM_READ | VM_EXEC))) goto bad_area; break; } /* * 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) current->maj_flt++; else current->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); monitor_signal(regs); /* User mode accesses just cause a SIGSEGV */ if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) { 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: monitor_signal(regs); /* Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) 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 pc:\n"); printk(KERN_ALERT "%08lx\n", regs->pc); #ifdef CONFIG_GDBSTUB gdbstub_intercept( regs, fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR); #endif page = PTBR; page = ((unsigned long *) __va(page))[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, fault_code); 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); monitor_signal(regs); printk(KERN_ALERT "VM: killing process %s\n", tsk->comm); if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) do_exit(SIGKILL); goto no_context; do_sigbus: up_read(&mm->mmap_sem); monitor_signal(regs); /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ 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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR) 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 index = pgd_index(address); pgd_t *pgd, *pgd_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; pte_t *pte_k; pgd_k = init_mm.pgd + index; if (!pgd_present(*pgd_k)) goto no_context; pud_k = pud_offset(pgd_k, address); if (!pud_present(*pud_k)) goto no_context; pmd_k = pmd_offset(pud_k, address); if (!pmd_present(*pmd_k)) goto no_context; pgd = (pgd_t *) PTBR + index; pud = pud_offset(pgd, address); pmd = pmd_offset(pud, address); set_pmd(pmd, *pmd_k); pte_k = pte_offset_kernel(pmd_k, address); if (!pte_present(*pte_k)) goto no_context; return; } }