diff options
Diffstat (limited to 'arch/m68k/mm/fault.c')
| -rw-r--r-- | arch/m68k/mm/fault.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c new file mode 100644 index 000000000..c290c5c0c --- /dev/null +++ b/arch/m68k/mm/fault.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/arch/m68k/mm/fault.c + * + * Copyright (C) 1995 Hamish Macdonald + */ + +#include <linux/mman.h> +#include <linux/mm.h> +#include <linux/kernel.h> +#include <linux/ptrace.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/uaccess.h> +#include <linux/perf_event.h> + +#include <asm/setup.h> +#include <asm/traps.h> + +extern void die_if_kernel(char *, struct pt_regs *, long); + +int send_fault_sig(struct pt_regs *regs) +{ + int signo, si_code; + void __user *addr; + + signo = current->thread.signo; + si_code = current->thread.code; + addr = (void __user *)current->thread.faddr; + pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code); + + if (user_mode(regs)) { + force_sig_fault(signo, si_code, addr); + } else { + if (fixup_exception(regs)) + return -1; + + //if (signo == SIGBUS) + // force_sig_fault(si_signo, si_code, addr); + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + if ((unsigned long)addr < PAGE_SIZE) + pr_alert("Unable to handle kernel NULL pointer dereference"); + else + pr_alert("Unable to handle kernel access"); + pr_cont(" at virtual address %p\n", addr); + die_if_kernel("Oops", regs, 0 /*error_code*/); + make_task_dead(SIGKILL); + } + + return 1; +} + +/* + * This routine handles page faults. It determines the problem, and + * then passes it off to one of the appropriate routines. + * + * error_code: + * bit 0 == 0 means no page found, 1 means protection fault + * bit 1 == 0 means read, 1 means write + * + * If this routine detects a bad access, it returns 1, otherwise it + * returns 0. + */ +int do_page_fault(struct pt_regs *regs, unsigned long address, + unsigned long error_code) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct * vma; + vm_fault_t fault; + unsigned int flags = FAULT_FLAG_DEFAULT; + + pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", + regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL); + + /* + * 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; + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); +retry: + mmap_read_lock(mm); + + vma = find_vma(mm, address); + if (!vma) + goto map_err; + if (vma->vm_start <= address) + goto good_area; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto map_err; + if (user_mode(regs)) { + /* Accessing the stack below usp is always a bug. The + "+ 256" is there due to some instructions doing + pre-decrement on the stack and that doesn't show up + until later. */ + if (address + 256 < rdusp()) + goto map_err; + } + vma = expand_stack(mm, address); + if (!vma) + goto map_err_nosemaphore; + +/* + * Ok, we have a good vm_area for this memory access, so + * we can handle it.. + */ +good_area: + pr_debug("do_page_fault: good_area\n"); + switch (error_code & 3) { + default: /* 3: write, present */ + fallthrough; + case 2: /* write, not present */ + if (!(vma->vm_flags & VM_WRITE)) + goto acc_err; + flags |= FAULT_FLAG_WRITE; + break; + case 1: /* read, present */ + goto acc_err; + case 0: /* read, not present */ + if (unlikely(!vma_is_accessible(vma))) + goto acc_err; + } + + /* + * 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, regs); + pr_debug("handle_mm_fault returns %x\n", fault); + + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; + return 0; + } + + /* The fault is fully completed (including releasing mmap lock) */ + if (fault & VM_FAULT_COMPLETED) + return 0; + + if (unlikely(fault & VM_FAULT_ERROR)) { + if (fault & VM_FAULT_OOM) + goto out_of_memory; + else if (fault & VM_FAULT_SIGSEGV) + goto map_err; + else if (fault & VM_FAULT_SIGBUS) + goto bus_err; + BUG(); + } + + if (fault & VM_FAULT_RETRY) { + flags |= FAULT_FLAG_TRIED; + + /* + * No need to mmap_read_unlock(mm) as we would + * have already released it in __lock_page_or_retry + * in mm/filemap.c. + */ + + goto retry; + } + + mmap_read_unlock(mm); + return 0; + +/* + * 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: + mmap_read_unlock(mm); + if (!user_mode(regs)) + goto no_context; + pagefault_out_of_memory(); + return 0; + +no_context: + current->thread.signo = SIGBUS; + current->thread.faddr = address; + return send_fault_sig(regs); + +bus_err: + current->thread.signo = SIGBUS; + current->thread.code = BUS_ADRERR; + current->thread.faddr = address; + goto send_sig; + +map_err: + mmap_read_unlock(mm); +map_err_nosemaphore: + current->thread.signo = SIGSEGV; + current->thread.code = SEGV_MAPERR; + current->thread.faddr = address; + return send_fault_sig(regs); + +acc_err: + current->thread.signo = SIGSEGV; + current->thread.code = SEGV_ACCERR; + current->thread.faddr = address; + +send_sig: + mmap_read_unlock(mm); + return send_fault_sig(regs); +} |