520 lines
11 KiB
C
520 lines
11 KiB
C
/*
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* Page fault handler for SH with an MMU.
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*
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* Copyright (C) 1999 Niibe Yutaka
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* Copyright (C) 2003 - 2012 Paul Mundt
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*
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* Based on linux/arch/i386/mm/fault.c:
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* Copyright (C) 1995 Linus Torvalds
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <linux/perf_event.h>
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#include <linux/kdebug.h>
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#include <linux/uaccess.h>
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#include <asm/io_trapped.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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#include <asm/traps.h>
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static inline int notify_page_fault(struct pt_regs *regs, int trap)
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{
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int ret = 0;
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if (kprobes_built_in() && !user_mode(regs)) {
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, trap))
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ret = 1;
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preempt_enable();
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}
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return ret;
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}
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static void
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force_sig_info_fault(int si_signo, int si_code, unsigned long address,
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struct task_struct *tsk)
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{
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siginfo_t info;
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info.si_signo = si_signo;
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info.si_errno = 0;
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info.si_code = si_code;
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info.si_addr = (void __user *)address;
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force_sig_info(si_signo, &info, tsk);
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}
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/*
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* This is useful to dump out the page tables associated with
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* 'addr' in mm 'mm'.
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*/
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static void show_pte(struct mm_struct *mm, unsigned long addr)
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{
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pgd_t *pgd;
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if (mm) {
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pgd = mm->pgd;
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} else {
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pgd = get_TTB();
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if (unlikely(!pgd))
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pgd = swapper_pg_dir;
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}
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printk(KERN_ALERT "pgd = %p\n", pgd);
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pgd += pgd_index(addr);
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printk(KERN_ALERT "[%08lx] *pgd=%0*Lx", addr,
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(u32)(sizeof(*pgd) * 2), (u64)pgd_val(*pgd));
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do {
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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if (pgd_none(*pgd))
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break;
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if (pgd_bad(*pgd)) {
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printk("(bad)");
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break;
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}
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pud = pud_offset(pgd, addr);
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if (PTRS_PER_PUD != 1)
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printk(", *pud=%0*Lx", (u32)(sizeof(*pud) * 2),
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(u64)pud_val(*pud));
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if (pud_none(*pud))
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break;
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if (pud_bad(*pud)) {
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printk("(bad)");
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break;
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}
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pmd = pmd_offset(pud, addr);
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if (PTRS_PER_PMD != 1)
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printk(", *pmd=%0*Lx", (u32)(sizeof(*pmd) * 2),
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(u64)pmd_val(*pmd));
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if (pmd_none(*pmd))
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break;
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if (pmd_bad(*pmd)) {
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printk("(bad)");
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break;
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}
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/* We must not map this if we have highmem enabled */
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if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
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break;
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pte = pte_offset_kernel(pmd, addr);
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printk(", *pte=%0*Lx", (u32)(sizeof(*pte) * 2),
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(u64)pte_val(*pte));
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} while (0);
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printk("\n");
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}
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static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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{
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unsigned index = pgd_index(address);
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pgd_t *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pgd += index;
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pgd_k = init_mm.pgd + index;
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if (!pgd_present(*pgd_k))
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return NULL;
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pud = pud_offset(pgd, address);
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pud_k = pud_offset(pgd_k, address);
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if (!pud_present(*pud_k))
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return NULL;
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if (!pud_present(*pud))
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set_pud(pud, *pud_k);
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pmd = pmd_offset(pud, address);
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pmd_k = pmd_offset(pud_k, address);
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if (!pmd_present(*pmd_k))
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return NULL;
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if (!pmd_present(*pmd))
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set_pmd(pmd, *pmd_k);
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else {
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/*
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* The page tables are fully synchronised so there must
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* be another reason for the fault. Return NULL here to
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* signal that we have not taken care of the fault.
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*/
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BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
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return NULL;
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}
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return pmd_k;
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}
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#ifdef CONFIG_SH_STORE_QUEUES
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#define __FAULT_ADDR_LIMIT P3_ADDR_MAX
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#else
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#define __FAULT_ADDR_LIMIT VMALLOC_END
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#endif
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/*
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* Handle a fault on the vmalloc or module mapping area
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*/
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static noinline int vmalloc_fault(unsigned long address)
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{
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pgd_t *pgd_k;
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pmd_t *pmd_k;
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pte_t *pte_k;
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/* Make sure we are in vmalloc/module/P3 area: */
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if (!(address >= VMALLOC_START && address < __FAULT_ADDR_LIMIT))
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return -1;
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/*
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* Synchronize this task's top level page-table
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* with the 'reference' page table.
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*
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* Do _not_ use "current" here. We might be inside
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* an interrupt in the middle of a task switch..
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*/
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pgd_k = get_TTB();
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pmd_k = vmalloc_sync_one(pgd_k, address);
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if (!pmd_k)
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return -1;
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pte_k = pte_offset_kernel(pmd_k, address);
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if (!pte_present(*pte_k))
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return -1;
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return 0;
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}
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static void
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show_fault_oops(struct pt_regs *regs, unsigned long address)
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{
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if (!oops_may_print())
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return;
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printk(KERN_ALERT "BUG: unable to handle kernel ");
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if (address < PAGE_SIZE)
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printk(KERN_CONT "NULL pointer dereference");
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else
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printk(KERN_CONT "paging request");
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printk(KERN_CONT " at %08lx\n", address);
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printk(KERN_ALERT "PC:");
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printk_address(regs->pc, 1);
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show_pte(NULL, address);
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}
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static noinline void
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no_context(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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/* Are we prepared to handle this kernel fault? */
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if (fixup_exception(regs))
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return;
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if (handle_trapped_io(regs, address))
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return;
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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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bust_spinlocks(1);
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show_fault_oops(regs, address);
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die("Oops", regs, error_code);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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}
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static void
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__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int si_code)
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{
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struct task_struct *tsk = current;
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/* User mode accesses just cause a SIGSEGV */
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if (user_mode(regs)) {
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/*
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* It's possible to have interrupts off here:
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*/
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local_irq_enable();
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force_sig_info_fault(SIGSEGV, si_code, address, tsk);
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return;
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}
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no_context(regs, error_code, address);
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}
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static noinline void
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bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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__bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
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}
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static void
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__bad_area(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int si_code)
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{
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struct mm_struct *mm = current->mm;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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up_read(&mm->mmap_sem);
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__bad_area_nosemaphore(regs, error_code, address, si_code);
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}
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static noinline void
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bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
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{
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__bad_area(regs, error_code, address, SEGV_MAPERR);
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}
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static noinline void
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bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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__bad_area(regs, error_code, address, SEGV_ACCERR);
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}
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static void
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do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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up_read(&mm->mmap_sem);
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/* Kernel mode? Handle exceptions or die: */
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if (!user_mode(regs))
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no_context(regs, error_code, address);
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force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
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}
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static noinline int
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mm_fault_error(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, unsigned int fault)
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{
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/*
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* Pagefault was interrupted by SIGKILL. We have no reason to
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* continue pagefault.
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*/
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if (fatal_signal_pending(current)) {
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if (!(fault & VM_FAULT_RETRY))
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up_read(¤t->mm->mmap_sem);
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if (!user_mode(regs))
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no_context(regs, error_code, address);
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return 1;
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}
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if (!(fault & VM_FAULT_ERROR))
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return 0;
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if (fault & VM_FAULT_OOM) {
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/* Kernel mode? Handle exceptions or die: */
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if (!user_mode(regs)) {
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up_read(¤t->mm->mmap_sem);
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no_context(regs, error_code, address);
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return 1;
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}
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up_read(¤t->mm->mmap_sem);
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/*
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* We ran out of memory, call the OOM killer, and return the
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* userspace (which will retry the fault, or kill us if we got
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* oom-killed):
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*/
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pagefault_out_of_memory();
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} else {
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if (fault & VM_FAULT_SIGBUS)
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do_sigbus(regs, error_code, address);
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else if (fault & VM_FAULT_SIGSEGV)
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bad_area(regs, error_code, address);
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else
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BUG();
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}
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return 1;
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}
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static inline int access_error(int error_code, struct vm_area_struct *vma)
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{
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if (error_code & FAULT_CODE_WRITE) {
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/* write, present and write, not present: */
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if (unlikely(!(vma->vm_flags & VM_WRITE)))
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return 1;
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return 0;
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}
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/* ITLB miss on NX page */
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if (unlikely((error_code & FAULT_CODE_ITLB) &&
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!(vma->vm_flags & VM_EXEC)))
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return 1;
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/* read, not present: */
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if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
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return 1;
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return 0;
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}
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static int fault_in_kernel_space(unsigned long address)
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{
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return address >= TASK_SIZE;
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*/
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asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
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unsigned long error_code,
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unsigned long address)
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{
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unsigned long vec;
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct * vma;
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int fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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tsk = current;
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mm = tsk->mm;
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vec = lookup_exception_vector();
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/*
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* We fault-in kernel-space virtual memory on-demand. The
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* 'reference' page table is init_mm.pgd.
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*
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* NOTE! We MUST NOT take any locks for this case. We may
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* be in an interrupt or a critical region, and should
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* only copy the information from the master page table,
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* nothing more.
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*/
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if (unlikely(fault_in_kernel_space(address))) {
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if (vmalloc_fault(address) >= 0)
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return;
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if (notify_page_fault(regs, vec))
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return;
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bad_area_nosemaphore(regs, error_code, address);
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return;
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}
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if (unlikely(notify_page_fault(regs, vec)))
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return;
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/* Only enable interrupts if they were on before the fault */
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if ((regs->sr & SR_IMASK) != SR_IMASK)
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local_irq_enable();
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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/*
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* If we're in an interrupt, have no user context or are running
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* with pagefaults disabled then we must not take the fault:
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*/
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if (unlikely(faulthandler_disabled() || !mm)) {
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bad_area_nosemaphore(regs, error_code, address);
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return;
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}
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retry:
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (unlikely(!vma)) {
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bad_area(regs, error_code, address);
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return;
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}
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if (likely(vma->vm_start <= address))
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goto good_area;
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if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
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bad_area(regs, error_code, address);
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return;
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}
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if (unlikely(expand_stack(vma, address))) {
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bad_area(regs, error_code, address);
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return;
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}
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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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if (unlikely(access_error(error_code, vma))) {
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bad_area_access_error(regs, error_code, address);
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return;
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}
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set_thread_fault_code(error_code);
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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if (error_code & FAULT_CODE_WRITE)
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flags |= FAULT_FLAG_WRITE;
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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);
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if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
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if (mm_fault_error(regs, error_code, address, fault))
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return;
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if (flags & FAULT_FLAG_ALLOW_RETRY) {
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if (fault & VM_FAULT_MAJOR) {
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tsk->maj_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
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regs, address);
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} else {
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tsk->min_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
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regs, address);
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}
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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* No need to up_read(&mm->mmap_sem) 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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}
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up_read(&mm->mmap_sem);
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}
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