| /* Page Fault Handling for ARC (TLB Miss / ProtV) |
| * |
| * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include <linux/signal.h> |
| #include <linux/interrupt.h> |
| #include <linux/sched/signal.h> |
| #include <linux/errno.h> |
| #include <linux/ptrace.h> |
| #include <linux/uaccess.h> |
| #include <linux/kdebug.h> |
| #include <linux/perf_event.h> |
| #include <linux/mm_types.h> |
| #include <asm/pgalloc.h> |
| #include <asm/mmu.h> |
| |
| /* |
| * kernel virtual address is required to implement vmalloc/pkmap/fixmap |
| * Refer to asm/processor.h for System Memory Map |
| * |
| * It simply copies the PMD entry (pointer to 2nd level page table or hugepage) |
| * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared |
| */ |
| noinline static int handle_kernel_vaddr_fault(unsigned long address) |
| { |
| /* |
| * Synchronize this task's top level page-table |
| * with the 'reference' page table. |
| */ |
| pgd_t *pgd, *pgd_k; |
| pud_t *pud, *pud_k; |
| pmd_t *pmd, *pmd_k; |
| |
| pgd = pgd_offset_fast(current->active_mm, address); |
| pgd_k = pgd_offset_k(address); |
| |
| if (!pgd_present(*pgd_k)) |
| goto bad_area; |
| |
| pud = pud_offset(pgd, address); |
| pud_k = pud_offset(pgd_k, address); |
| if (!pud_present(*pud_k)) |
| goto bad_area; |
| |
| pmd = pmd_offset(pud, address); |
| pmd_k = pmd_offset(pud_k, address); |
| if (!pmd_present(*pmd_k)) |
| goto bad_area; |
| |
| set_pmd(pmd, *pmd_k); |
| |
| /* XXX: create the TLB entry here */ |
| return 0; |
| |
| bad_area: |
| return 1; |
| } |
| |
| void do_page_fault(unsigned long address, struct pt_regs *regs) |
| { |
| struct vm_area_struct *vma = NULL; |
| struct task_struct *tsk = current; |
| struct mm_struct *mm = tsk->mm; |
| int si_code = 0; |
| int ret; |
| vm_fault_t fault; |
| int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
| unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
| |
| /* |
| * 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 (address >= VMALLOC_START) { |
| ret = handle_kernel_vaddr_fault(address); |
| if (unlikely(ret)) |
| goto bad_area_nosemaphore; |
| else |
| return; |
| } |
| |
| si_code = SEGV_MAPERR; |
| |
| /* |
| * If we're in an interrupt or have no user |
| * context, we must not take the fault.. |
| */ |
| if (faulthandler_disabled() || !mm) |
| goto no_context; |
| |
| if (user_mode(regs)) |
| flags |= FAULT_FLAG_USER; |
| 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 (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; |
| |
| /* Handle protection violation, execute on heap or stack */ |
| |
| if ((regs->ecr_vec == ECR_V_PROTV) && |
| (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) |
| goto bad_area; |
| |
| if (write) { |
| if (!(vma->vm_flags & VM_WRITE)) |
| goto bad_area; |
| flags |= FAULT_FLAG_WRITE; |
| } else { |
| if (!(vma->vm_flags & (VM_READ | VM_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 Pagefault was interrupted by SIGKILL, exit page fault "early" */ |
| if (fatal_signal_pending(current)) { |
| if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY)) |
| up_read(&mm->mmap_sem); |
| if (user_mode(regs)) |
| return; |
| } |
| |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
| |
| if (likely(!(fault & VM_FAULT_ERROR))) { |
| if (flags & FAULT_FLAG_ALLOW_RETRY) { |
| /* To avoid updating stats twice for retry case */ |
| if (fault & VM_FAULT_MAJOR) { |
| tsk->maj_flt++; |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
| regs, address); |
| } else { |
| tsk->min_flt++; |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
| regs, address); |
| } |
| |
| if (fault & VM_FAULT_RETRY) { |
| flags &= ~FAULT_FLAG_ALLOW_RETRY; |
| flags |= FAULT_FLAG_TRIED; |
| goto retry; |
| } |
| } |
| |
| /* Fault Handled Gracefully */ |
| up_read(&mm->mmap_sem); |
| return; |
| } |
| |
| 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; |
| |
| /* no man's land */ |
| BUG(); |
| |
| /* |
| * 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.fault_address = address; |
| force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk); |
| return; |
| } |
| |
| no_context: |
| /* Are we prepared to handle this kernel fault? |
| * |
| * (The kernel has valid exception-points in the source |
| * when it accesses 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) |
| */ |
| if (fixup_exception(regs)) |
| return; |
| |
| die("Oops", regs, address); |
| |
| out_of_memory: |
| up_read(&mm->mmap_sem); |
| |
| if (user_mode(regs)) { |
| pagefault_out_of_memory(); |
| return; |
| } |
| |
| goto no_context; |
| |
| do_sigbus: |
| up_read(&mm->mmap_sem); |
| |
| if (!user_mode(regs)) |
| goto no_context; |
| |
| tsk->thread.fault_address = address; |
| force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk); |
| } |