| /* |
| * OpenRISC fault.c |
| * |
| * Linux architectural port borrowing liberally from similar works of |
| * others. All original copyrights apply as per the original source |
| * declaration. |
| * |
| * Modifications for the OpenRISC architecture: |
| * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> |
| * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/interrupt.h> |
| #include <linux/extable.h> |
| #include <linux/sched/signal.h> |
| |
| #include <linux/uaccess.h> |
| #include <asm/siginfo.h> |
| #include <asm/signal.h> |
| |
| #define NUM_TLB_ENTRIES 64 |
| #define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1)) |
| |
| unsigned long pte_misses; /* updated by do_page_fault() */ |
| unsigned long pte_errors; /* updated by do_page_fault() */ |
| |
| /* __PHX__ :: - check the vmalloc_fault in do_page_fault() |
| * - also look into include/asm-or32/mmu_context.h |
| */ |
| volatile pgd_t *current_pgd[NR_CPUS]; |
| |
| extern void die(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. |
| * |
| * If this routine detects a bad access, it returns 1, otherwise it |
| * returns 0. |
| */ |
| |
| asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address, |
| unsigned long vector, int write_acc) |
| { |
| struct task_struct *tsk; |
| struct mm_struct *mm; |
| struct vm_area_struct *vma; |
| siginfo_t info; |
| int fault; |
| unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
| |
| clear_siginfo(&info); |
| 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. |
| * |
| * NOTE2: This is done so that, when updating the vmalloc |
| * mappings we don't have to walk all processes pgdirs and |
| * add the high mappings all at once. Instead we do it as they |
| * are used. However vmalloc'ed page entries have the PAGE_GLOBAL |
| * bit set so sometimes the TLB can use a lingering entry. |
| * |
| * This verifies that the fault happens in kernel space |
| * and that the fault was not a protection error. |
| */ |
| |
| if (address >= VMALLOC_START && |
| (vector != 0x300 && vector != 0x400) && |
| !user_mode(regs)) |
| goto vmalloc_fault; |
| |
| /* If exceptions were enabled, we can reenable them here */ |
| if (user_mode(regs)) { |
| /* Exception was in userspace: reenable interrupts */ |
| local_irq_enable(); |
| flags |= FAULT_FLAG_USER; |
| } else { |
| /* If exception was in a syscall, then IRQ's may have |
| * been enabled or disabled. If they were enabled, |
| * reenable them. |
| */ |
| if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE)) |
| local_irq_enable(); |
| } |
| |
| 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; |
| |
| retry: |
| 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 (user_mode(regs)) { |
| /* |
| * accessing the stack below usp is always a bug. |
| * we get page-aligned addresses so we can only check |
| * if we're within a page from usp, but that might be |
| * enough to catch brutal errors at least. |
| */ |
| if (address + PAGE_SIZE < regs->sp) |
| 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; |
| |
| /* first do some preliminary protection checks */ |
| |
| if (write_acc) { |
| if (!(vma->vm_flags & VM_WRITE)) |
| goto bad_area; |
| flags |= FAULT_FLAG_WRITE; |
| } else { |
| /* not present */ |
| if (!(vma->vm_flags & (VM_READ | VM_EXEC))) |
| goto bad_area; |
| } |
| |
| /* are we trying to execute nonexecutable area */ |
| if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC)) |
| 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(vma, address, flags); |
| |
| if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) |
| return; |
| |
| if (unlikely(fault & VM_FAULT_ERROR)) { |
| if (fault & VM_FAULT_OOM) |
| goto out_of_memory; |
| else if (fault & VM_FAULT_SIGSEGV) |
| goto bad_area; |
| else if (fault & VM_FAULT_SIGBUS) |
| goto do_sigbus; |
| BUG(); |
| } |
| |
| if (flags & FAULT_FLAG_ALLOW_RETRY) { |
| /*RGD modeled on Cris */ |
| if (fault & VM_FAULT_MAJOR) |
| tsk->maj_flt++; |
| else |
| tsk->min_flt++; |
| if (fault & VM_FAULT_RETRY) { |
| flags &= ~FAULT_FLAG_ALLOW_RETRY; |
| flags |= FAULT_FLAG_TRIED; |
| |
| /* No need to up_read(&mm->mmap_sem) as we would |
| * have already released it in __lock_page_or_retry |
| * in mm/filemap.c. |
| */ |
| |
| goto retry; |
| } |
| } |
| |
| 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)) { |
| 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? |
| * |
| * (The kernel has valid exception-points in the source |
| * when it acesses user-memory. When it fails in one |
| * of those points, we find it in a table and do a jump |
| * to some fixup code that loads an appropriate error |
| * code) |
| */ |
| |
| { |
| const struct exception_table_entry *entry; |
| |
| __asm__ __volatile__("l.nop 42"); |
| |
| if ((entry = search_exception_tables(regs->pc)) != NULL) { |
| /* Adjust the instruction pointer in the stackframe */ |
| regs->pc = entry->fixup; |
| return; |
| } |
| } |
| |
| /* |
| * Oops. The kernel tried to access some bad page. We'll have to |
| * terminate things with extreme prejudice. |
| */ |
| |
| if ((unsigned long)(address) < PAGE_SIZE) |
| printk(KERN_ALERT |
| "Unable to handle kernel NULL pointer dereference"); |
| else |
| printk(KERN_ALERT "Unable to handle kernel access"); |
| printk(" at virtual address 0x%08lx\n", address); |
| |
| die("Oops", regs, write_acc); |
| |
| 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: |
| __asm__ __volatile__("l.nop 42"); |
| __asm__ __volatile__("l.nop 1"); |
| |
| up_read(&mm->mmap_sem); |
| if (!user_mode(regs)) |
| goto no_context; |
| pagefault_out_of_memory(); |
| return; |
| |
| 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; |
| return; |
| |
| vmalloc_fault: |
| { |
| /* |
| * Synchronize this task's top level page-table |
| * with the 'reference' page table. |
| * |
| * Use current_pgd instead of tsk->active_mm->pgd |
| * since the latter might be unavailable if this |
| * code is executed in a misfortunately run irq |
| * (like inside schedule() between switch_mm and |
| * switch_to...). |
| */ |
| |
| int offset = pgd_index(address); |
| pgd_t *pgd, *pgd_k; |
| pud_t *pud, *pud_k; |
| pmd_t *pmd, *pmd_k; |
| pte_t *pte_k; |
| |
| /* |
| phx_warn("do_page_fault(): vmalloc_fault will not work, " |
| "since current_pgd assign a proper value somewhere\n" |
| "anyhow we don't need this at the moment\n"); |
| |
| phx_mmu("vmalloc_fault"); |
| */ |
| pgd = (pgd_t *)current_pgd[smp_processor_id()] + offset; |
| pgd_k = init_mm.pgd + offset; |
| |
| /* Since we're two-level, we don't need to do both |
| * set_pgd and set_pmd (they do the same thing). If |
| * we go three-level at some point, do the right thing |
| * with pgd_present and set_pgd here. |
| * |
| * Also, since the vmalloc area is global, we don't |
| * need to copy individual PTE's, it is enough to |
| * copy the pgd pointer into the pte page of the |
| * root task. If that is there, we'll find our pte if |
| * it exists. |
| */ |
| |
| pud = pud_offset(pgd, address); |
| pud_k = pud_offset(pgd_k, address); |
| if (!pud_present(*pud_k)) |
| goto no_context; |
| |
| pmd = pmd_offset(pud, address); |
| pmd_k = pmd_offset(pud_k, address); |
| |
| if (!pmd_present(*pmd_k)) |
| goto bad_area_nosemaphore; |
| |
| set_pmd(pmd, *pmd_k); |
| |
| /* Make sure the actual PTE exists as well to |
| * catch kernel vmalloc-area accesses to non-mapped |
| * addresses. If we don't do this, this will just |
| * silently loop forever. |
| */ |
| |
| pte_k = pte_offset_kernel(pmd_k, address); |
| if (!pte_present(*pte_k)) |
| goto no_context; |
| |
| return; |
| } |
| } |