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209 lines
4.8 KiB
209 lines
4.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/arch/m68k/mm/fault.c |
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* |
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* Copyright (C) 1995 Hamish Macdonald |
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*/ |
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#include <linux/mman.h> |
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#include <linux/mm.h> |
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#include <linux/kernel.h> |
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#include <linux/ptrace.h> |
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#include <linux/interrupt.h> |
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#include <linux/module.h> |
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#include <linux/uaccess.h> |
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#include <linux/perf_event.h> |
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#include <asm/setup.h> |
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#include <asm/traps.h> |
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extern void die_if_kernel(char *, struct pt_regs *, long); |
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int send_fault_sig(struct pt_regs *regs) |
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{ |
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int signo, si_code; |
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void __user *addr; |
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signo = current->thread.signo; |
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si_code = current->thread.code; |
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addr = (void __user *)current->thread.faddr; |
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pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code); |
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if (user_mode(regs)) { |
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force_sig_fault(signo, si_code, addr); |
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} else { |
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if (fixup_exception(regs)) |
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return -1; |
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//if (signo == SIGBUS) |
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// force_sig_fault(si_signo, si_code, addr); |
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/* |
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* Oops. The kernel tried to access some bad page. We'll have to |
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* terminate things with extreme prejudice. |
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*/ |
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if ((unsigned long)addr < PAGE_SIZE) |
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pr_alert("Unable to handle kernel NULL pointer dereference"); |
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else |
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pr_alert("Unable to handle kernel access"); |
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pr_cont(" at virtual address %p\n", addr); |
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die_if_kernel("Oops", regs, 0 /*error_code*/); |
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make_task_dead(SIGKILL); |
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} |
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return 1; |
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} |
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/* |
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* This routine handles page faults. It determines the problem, and |
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* then passes it off to one of the appropriate routines. |
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* |
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* error_code: |
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* bit 0 == 0 means no page found, 1 means protection fault |
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* bit 1 == 0 means read, 1 means write |
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* |
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* If this routine detects a bad access, it returns 1, otherwise it |
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* returns 0. |
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*/ |
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int do_page_fault(struct pt_regs *regs, unsigned long address, |
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unsigned long error_code) |
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{ |
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struct mm_struct *mm = current->mm; |
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struct vm_area_struct * vma; |
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vm_fault_t fault; |
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unsigned int flags = FAULT_FLAG_DEFAULT; |
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pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", |
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regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL); |
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/* |
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* If we're in an interrupt or have no user |
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* context, we must not take the fault.. |
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*/ |
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if (faulthandler_disabled() || !mm) |
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goto no_context; |
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if (user_mode(regs)) |
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flags |= FAULT_FLAG_USER; |
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
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retry: |
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mmap_read_lock(mm); |
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vma = find_vma(mm, address); |
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if (!vma) |
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goto map_err; |
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if (vma->vm_start <= address) |
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goto good_area; |
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if (!(vma->vm_flags & VM_GROWSDOWN)) |
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goto map_err; |
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if (user_mode(regs)) { |
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/* Accessing the stack below usp is always a bug. The |
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"+ 256" is there due to some instructions doing |
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pre-decrement on the stack and that doesn't show up |
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until later. */ |
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if (address + 256 < rdusp()) |
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goto map_err; |
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} |
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if (expand_stack(vma, address)) |
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goto map_err; |
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/* |
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* Ok, we have a good vm_area for this memory access, so |
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* we can handle it.. |
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*/ |
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good_area: |
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pr_debug("do_page_fault: good_area\n"); |
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switch (error_code & 3) { |
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default: /* 3: write, present */ |
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fallthrough; |
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case 2: /* write, not present */ |
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if (!(vma->vm_flags & VM_WRITE)) |
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goto acc_err; |
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flags |= FAULT_FLAG_WRITE; |
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break; |
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case 1: /* read, present */ |
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goto acc_err; |
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case 0: /* read, not present */ |
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if (unlikely(!vma_is_accessible(vma))) |
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goto acc_err; |
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} |
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/* |
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* If for any reason at all we couldn't handle the fault, |
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* make sure we exit gracefully rather than endlessly redo |
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* the fault. |
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*/ |
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fault = handle_mm_fault(vma, address, flags, regs); |
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pr_debug("handle_mm_fault returns %x\n", fault); |
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if (fault_signal_pending(fault, regs)) |
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return 0; |
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/* The fault is fully completed (including releasing mmap lock) */ |
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if (fault & VM_FAULT_COMPLETED) |
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return 0; |
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if (unlikely(fault & VM_FAULT_ERROR)) { |
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if (fault & VM_FAULT_OOM) |
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goto out_of_memory; |
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else if (fault & VM_FAULT_SIGSEGV) |
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goto map_err; |
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else if (fault & VM_FAULT_SIGBUS) |
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goto bus_err; |
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BUG(); |
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} |
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if (fault & VM_FAULT_RETRY) { |
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flags |= FAULT_FLAG_TRIED; |
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/* |
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* No need to mmap_read_unlock(mm) as we would |
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* have already released it in __lock_page_or_retry |
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* in mm/filemap.c. |
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*/ |
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goto retry; |
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} |
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mmap_read_unlock(mm); |
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return 0; |
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/* |
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* We ran out of memory, or some other thing happened to us that made |
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* us unable to handle the page fault gracefully. |
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*/ |
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out_of_memory: |
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mmap_read_unlock(mm); |
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if (!user_mode(regs)) |
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goto no_context; |
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pagefault_out_of_memory(); |
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return 0; |
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no_context: |
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current->thread.signo = SIGBUS; |
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current->thread.faddr = address; |
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return send_fault_sig(regs); |
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bus_err: |
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current->thread.signo = SIGBUS; |
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current->thread.code = BUS_ADRERR; |
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current->thread.faddr = address; |
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goto send_sig; |
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map_err: |
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current->thread.signo = SIGSEGV; |
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current->thread.code = SEGV_MAPERR; |
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current->thread.faddr = address; |
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goto send_sig; |
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acc_err: |
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current->thread.signo = SIGSEGV; |
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current->thread.code = SEGV_ACCERR; |
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current->thread.faddr = address; |
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send_sig: |
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mmap_read_unlock(mm); |
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return send_fault_sig(regs); |
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}
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