diff options
Diffstat (limited to 'arch/metag/mm/fault.c')
| -rw-r--r-- | arch/metag/mm/fault.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c new file mode 100644 index 000000000000..2c75bf7357c5 --- /dev/null +++ b/arch/metag/mm/fault.c @@ -0,0 +1,239 @@ +/* + * Meta page fault handling. + * + * Copyright (C) 2005-2012 Imagination Technologies Ltd. + */ + +#include <linux/mman.h> +#include <linux/mm.h> +#include <linux/kernel.h> +#include <linux/ptrace.h> +#include <linux/interrupt.h> +#include <linux/uaccess.h> + +#include <asm/tlbflush.h> +#include <asm/mmu.h> +#include <asm/traps.h> + +/* Clear any pending catch buffer state. */ +static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr, + unsigned int trapno) +{ + PTBICTXEXTCB0 cbuf = regs->extcb0; + + switch (trapno) { + /* Instruction fetch faults leave no catch buffer state. */ + case TBIXXF_SIGNUM_IGF: + case TBIXXF_SIGNUM_IPF: + return; + default: + if (cbuf[0].CBAddr == addr) { + cbuf[0].CBAddr = 0; + cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS; + + /* And, as this is the ONLY catch entry, we + * need to clear the cbuf bit from the context! + */ + regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT | + TBICTX_XCBF_BIT); + + return; + } + pr_err("Failed to clear cbuf entry!\n"); + } +} + +int show_unhandled_signals = 1; + +int do_page_fault(struct pt_regs *regs, unsigned long address, + unsigned int write_access, unsigned int trapno) +{ + struct task_struct *tsk; + struct mm_struct *mm; + struct vm_area_struct *vma, *prev_vma; + siginfo_t info; + int fault; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | + (write_access ? FAULT_FLAG_WRITE : 0); + + tsk = current; + + if ((address >= VMALLOC_START) && (address < VMALLOC_END)) { + /* + * 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_index(address); + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + + pgd = ((pgd_t *)mmu_get_base()) + offset; + pgd_k = swapper_pg_dir + offset; + + /* This will never happen with the folded page table. */ + if (!pgd_present(*pgd)) { + if (!pgd_present(*pgd_k)) + goto bad_area_nosemaphore; + set_pgd(pgd, *pgd_k); + return 0; + } + + pud = pud_offset(pgd, address); + pud_k = pud_offset(pgd_k, address); + if (!pud_present(*pud_k)) + goto bad_area_nosemaphore; + set_pud(pud, *pud_k); + + 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); + + pte_k = pte_offset_kernel(pmd_k, address); + if (!pte_present(*pte_k)) + goto bad_area_nosemaphore; + + /* May only be needed on Chorus2 */ + flush_tlb_all(); + return 0; + } + + mm = tsk->mm; + + if (in_atomic() || !mm) + goto no_context; + +retry: + down_read(&mm->mmap_sem); + + vma = find_vma_prev(mm, address, &prev_vma); + + if (!vma || address < vma->vm_start) + goto check_expansion; + +good_area: + if (write_access) { + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + } else { + if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) + 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 0; + + if (unlikely(fault & VM_FAULT_ERROR)) { + if (fault & VM_FAULT_OOM) + goto out_of_memory; + else if (fault & VM_FAULT_SIGBUS) + goto do_sigbus; + BUG(); + } + if (flags & FAULT_FLAG_ALLOW_RETRY) { + 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 0; + +check_expansion: + vma = prev_vma; + if (vma && (expand_stack(vma, address) == 0)) + goto good_area; + +bad_area: + up_read(&mm->mmap_sem); + +bad_area_nosemaphore: + if (user_mode(regs)) { + info.si_signo = SIGSEGV; + info.si_errno = 0; + info.si_code = SEGV_MAPERR; + info.si_addr = (__force void __user *)address; + info.si_trapno = trapno; + + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && + printk_ratelimit()) { + pr_info("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)", + task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, + tsk->comm, task_pid_nr(tsk), address, + regs->ctx.CurrPC, regs->ctx.AX[0].U0, + write_access, trapno, trap_name(trapno)); + print_vma_addr(" in ", regs->ctx.CurrPC); + print_vma_addr(" rtp in ", regs->ctx.DX[4].U1); + printk("\n"); + show_regs(regs); + } + force_sig_info(SIGSEGV, &info, tsk); + return 1; + } + goto no_context; + +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 = (__force void __user *)address; + info.si_trapno = trapno; + force_sig_info(SIGBUS, &info, tsk); + + /* Kernel mode? Handle exceptions or die */ + if (!user_mode(regs)) + goto no_context; + + return 1; + + /* + * 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: + up_read(&mm->mmap_sem); + if (user_mode(regs)) + do_group_exit(SIGKILL); + +no_context: + /* Are we prepared to handle this kernel fault? */ + if (fixup_exception(regs)) { + clear_cbuf_entry(regs, address, trapno); + return 1; + } + + die("Oops", regs, (write_access << 15) | trapno, address); + do_exit(SIGKILL); +} |