From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/mips/mm/fault.c | 342 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 342 insertions(+) create mode 100644 arch/mips/mm/fault.c (limited to 'arch/mips/mm/fault.c') diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c new file mode 100644 index 000000000..7ff8637e5 --- /dev/null +++ b/arch/mips/mm/fault.c @@ -0,0 +1,342 @@ +/* + * 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. + * + * Copyright (C) 1995 - 2000 by Ralf Baechle + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include /* For VMALLOC_END */ +#include + +int show_unhandled_signals = 1; + +/* + * This routine handles page faults. It determines the address, + * and the problem, and then passes it off to one of the appropriate + * routines. + */ +static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write, + unsigned long address) +{ + struct vm_area_struct * vma = NULL; + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + const int field = sizeof(unsigned long) * 2; + siginfo_t info; + int fault; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + + static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); + +#if 0 + printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), + current->comm, current->pid, field, address, write, + field, regs->cp0_epc); +#endif + +#ifdef CONFIG_KPROBES + /* + * This is to notify the fault handler of the kprobes. The + * exception code is redundant as it is also carried in REGS, + * but we pass it anyhow. + */ + if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1, + (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP) + return; +#endif + + info.si_code = SEGV_MAPERR; + + /* + * 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. + */ +#ifdef CONFIG_64BIT +# define VMALLOC_FAULT_TARGET no_context +#else +# define VMALLOC_FAULT_TARGET vmalloc_fault +#endif + + if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) + goto VMALLOC_FAULT_TARGET; +#ifdef MODULE_START + if (unlikely(address >= MODULE_START && address < MODULE_END)) + goto VMALLOC_FAULT_TARGET; +#endif + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_atomic() || !mm) + goto bad_area_nosemaphore; + + 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: + info.si_code = SEGV_ACCERR; + + if (write) { + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + flags |= FAULT_FLAG_WRITE; + } else { + if (cpu_has_rixi) { + if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) { +#if 0 + pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n", + raw_smp_processor_id(), + current->comm, current->pid, + field, address, write, + field, regs->cp0_epc); +#endif + goto bad_area; + } + if (!(vma->vm_flags & VM_READ)) { +#if 0 + pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n", + raw_smp_processor_id(), + current->comm, current->pid, + field, address, write, + field, regs->cp0_epc); +#endif + goto bad_area; + } + } else { + if (!(vma->vm_flags & (VM_READ | VM_WRITE | 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(mm, vma, address, flags); + + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + return; + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + 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) { + if (fault & VM_FAULT_MAJOR) { + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, + regs, address); + tsk->maj_flt++; + } else { + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, + regs, address); + 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)) { + tsk->thread.cp0_badvaddr = address; + tsk->thread.error_code = write; + if (show_unhandled_signals && + unhandled_signal(tsk, SIGSEGV) && + __ratelimit(&ratelimit_state)) { + pr_info("\ndo_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx", + tsk->comm, + write ? "write access to" : "read access from", + field, address); + pr_info("epc = %0*lx in", field, + (unsigned long) regs->cp0_epc); + print_vma_addr(" ", regs->cp0_epc); + pr_info("ra = %0*lx in", field, + (unsigned long) regs->regs[31]); + print_vma_addr(" ", regs->regs[31]); + pr_info("\n"); + } + info.si_signo = SIGSEGV; + info.si_errno = 0; + /* info.si_code has been set above */ + info.si_addr = (void __user *) address; + force_sig_info(SIGSEGV, &info, tsk); + return; + } + +no_context: + /* Are we prepared to handle this kernel fault? */ + if (fixup_exception(regs)) { + current->thread.cp0_baduaddr = address; + return; + } + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + bust_spinlocks(1); + + printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " + "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", + raw_smp_processor_id(), field, address, field, regs->cp0_epc, + field, regs->regs[31]); + die("Oops", regs); + +out_of_memory: + /* + * We ran out of memory, call the OOM killer, and return the userspace + * (which will retry the fault, or kill us if we got oom-killed). + */ + up_read(&mm->mmap_sem); + if (!user_mode(regs)) + goto no_context; + pagefault_out_of_memory(); + return; + +do_sigbus: + up_read(&mm->mmap_sem); + + /* Kernel mode? Handle exceptions or die */ + if (!user_mode(regs)) + goto no_context; + else + /* + * Send a sigbus, regardless of whether we were in kernel + * or user mode. + */ +#if 0 + printk("do_page_fault() #3: sending SIGBUS to %s for " + "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", + tsk->comm, + write ? "write access to" : "read access from", + field, address, + field, (unsigned long) regs->cp0_epc, + field, (unsigned long) regs->regs[31]); +#endif + tsk->thread.cp0_badvaddr = address; + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = BUS_ADRERR; + info.si_addr = (void __user *) address; + force_sig_info(SIGBUS, &info, tsk); + + return; +#ifndef CONFIG_64BIT +vmalloc_fault: + { + /* + * 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_offset(address); + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + + pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; + pgd_k = init_mm.pgd + offset; + + if (!pgd_present(*pgd_k)) + goto no_context; + set_pgd(pgd, *pgd_k); + + 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 no_context; + set_pmd(pmd, *pmd_k); + + pte_k = pte_offset_kernel(pmd_k, address); + if (!pte_present(*pte_k)) + goto no_context; + return; + } +#endif +} + +asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, + unsigned long write, unsigned long address) +{ + enum ctx_state prev_state; + + prev_state = exception_enter(); + __do_page_fault(regs, write, address); + exception_exit(prev_state); +} -- cgit v1.2.3-54-g00ecf