+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0
-/*
- * 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/sched/debug.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;
-
- 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 (faulthandler_disabled() || !mm)
- goto no_context;
-
- if (user_mode(regs))
- flags |= FAULT_FLAG_USER;
-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;
- flags |= FAULT_FLAG_WRITE;
- } 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(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_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)
- 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()) {
- printk("%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)) {
- pagefault_out_of_memory();
- return 1;
- }
-
-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);
-}
git.samba.org / sfrench / cifs-2.6.git / blobdiff