/* * Page fault handler for SH with an MMU. * * Copyright (C) 1999 Niibe Yutaka * Copyright (C) 2003 Paul Mundt * * Based on linux/arch/i386/mm/fault.c: * Copyright (C) 1995 Linus Torvalds * * 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. */ #include <linux/kernel.h> #include <linux/mm.h> #include <linux/hardirq.h> #include <linux/kprobes.h> #include <asm/system.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> #include <asm/kgdb.h> extern void die(const char *,struct pt_regs *,long); /* * 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 writeaccess, unsigned long address) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct * vma; unsigned long page; int si_code; siginfo_t info; trace_hardirqs_on(); local_irq_enable(); #ifdef CONFIG_SH_KGDB if (kgdb_nofault && kgdb_bus_err_hook) kgdb_bus_err_hook(); #endif tsk = current; mm = tsk->mm; si_code = SEGV_MAPERR; if (unlikely(address >= TASK_SIZE)) { /* * 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_index(address); pgd_t *pgd, *pgd_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; pgd = get_TTB() + offset; pgd_k = swapper_pg_dir + offset; /* This will never happen with the folded page table. */ if (!pgd_present(*pgd)) { if (!pgd_present(*pgd_k)) goto bad_area_nosemaphore; set_pgd(pgd, *pgd_k); return; } pud = pud_offset(pgd, address); pud_k = pud_offset(pgd_k, address); if (pud_present(*pud) || !pud_present(*pud_k)) goto bad_area_nosemaphore; set_pud(pud, *pud_k); pmd = pmd_offset(pud, address); pmd_k = pmd_offset(pud_k, address); if (pmd_present(*pmd) || !pmd_present(*pmd_k)) goto bad_area_nosemaphore; set_pmd(pmd, *pmd_k); return; } /* * 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 (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: si_code = SEGV_ACCERR; if (writeaccess) { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; } else { 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. */ survive: switch (handle_mm_fault(mm, vma, address, writeaccess)) { 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: if (user_mode(regs)) { info.si_signo = SIGSEGV; info.si_errno = 0; info.si_code = si_code; 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)) return; /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. * */ 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(KERN_ALERT "pc = %08lx\n", regs->pc); page = (unsigned long)get_TTB(); if (page) { page = ((unsigned long *) page)[address >> PGDIR_SHIFT]; printk(KERN_ALERT "*pde = %08lx\n", page); if (page & _PAGE_PRESENT) { page &= PAGE_MASK; address &= 0x003ff000; page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT]; printk(KERN_ALERT "*pte = %08lx\n", page); } } die("Oops", regs, writeaccess); 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_init(current)) { 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); /* * 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 (!user_mode(regs)) goto no_context; } #ifdef CONFIG_SH_STORE_QUEUES /* * This is a special case for the SH-4 store queues, as pages for this * space still need to be faulted in before it's possible to flush the * store queue cache for writeout to the remapped region. */ #define P3_ADDR_MAX (P4SEG_STORE_QUE + 0x04000000) #else #define P3_ADDR_MAX P4SEG #endif /* * Called with interrupts disabled. */ asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs, unsigned long writeaccess, unsigned long address) { pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *pte; pte_t entry; struct mm_struct *mm = current->mm; spinlock_t *ptl; int ret = 1; #ifdef CONFIG_SH_KGDB if (kgdb_nofault && kgdb_bus_err_hook) kgdb_bus_err_hook(); #endif /* * We don't take page faults for P1, P2, and parts of P4, these * are always mapped, whether it be due to legacy behaviour in * 29-bit mode, or due to PMB configuration in 32-bit mode. */ if (address >= P3SEG && address < P3_ADDR_MAX) { pgd = pgd_offset_k(address); mm = NULL; } else { if (unlikely(address >= TASK_SIZE || !mm)) return 1; pgd = pgd_offset(mm, address); } pud = pud_offset(pgd, address); if (pud_none_or_clear_bad(pud)) return 1; pmd = pmd_offset(pud, address); if (pmd_none_or_clear_bad(pmd)) return 1; if (mm) pte = pte_offset_map_lock(mm, pmd, address, &ptl); else pte = pte_offset_kernel(pmd, address); entry = *pte; if (unlikely(pte_none(entry) || pte_not_present(entry))) goto unlock; if (unlikely(writeaccess && !pte_write(entry))) goto unlock; if (writeaccess) entry = pte_mkdirty(entry); entry = pte_mkyoung(entry); #ifdef CONFIG_CPU_SH4 /* * ITLB is not affected by "ldtlb" instruction. * So, we need to flush the entry by ourselves. */ local_flush_tlb_one(get_asid(), address & PAGE_MASK); #endif set_pte(pte, entry); update_mmu_cache(NULL, address, entry); ret = 0; unlock: if (mm) pte_unmap_unlock(pte, ptl); return ret; }