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500 lines
11 KiB
500 lines
11 KiB
/* |
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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/sched/signal.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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|
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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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{ |
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force_sig_fault(si_signo, si_code, (void __user *)address); |
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} |
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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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|
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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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pr_alert("pgd = %p\n", pgd); |
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pgd += pgd_index(addr); |
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pr_alert("[%08lx] *pgd=%0*llx", addr, (u32)(sizeof(*pgd) * 2), |
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(u64)pgd_val(*pgd)); |
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do { |
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p4d_t *p4d; |
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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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pr_cont("(bad)"); |
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break; |
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} |
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p4d = p4d_offset(pgd, addr); |
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if (PTRS_PER_P4D != 1) |
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pr_cont(", *p4d=%0*Lx", (u32)(sizeof(*p4d) * 2), |
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(u64)p4d_val(*p4d)); |
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if (p4d_none(*p4d)) |
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break; |
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if (p4d_bad(*p4d)) { |
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pr_cont("(bad)"); |
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break; |
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} |
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pud = pud_offset(p4d, addr); |
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if (PTRS_PER_PUD != 1) |
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pr_cont(", *pud=%0*llx", (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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pr_cont("(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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pr_cont(", *pmd=%0*llx", (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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pr_cont("(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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pr_cont(", *pte=%0*llx", (u32)(sizeof(*pte) * 2), |
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(u64)pte_val(*pte)); |
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} while (0); |
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pr_cont("\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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p4d_t *p4d, *p4d_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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p4d = p4d_offset(pgd, address); |
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p4d_k = p4d_offset(pgd_k, address); |
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if (!p4d_present(*p4d_k)) |
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return NULL; |
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pud = pud_offset(p4d, address); |
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pud_k = pud_offset(p4d_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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pr_alert("BUG: unable to handle kernel %s at %08lx\n", |
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address < PAGE_SIZE ? "NULL pointer dereference" |
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: "paging request", |
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address); |
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pr_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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} |
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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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/* 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); |
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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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mmap_read_unlock(mm); |
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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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mmap_read_unlock(mm); |
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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); |
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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, vm_fault_t 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 (fault_signal_pending(fault, regs)) { |
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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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/* Release mmap_lock first if necessary */ |
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if (!(fault & VM_FAULT_RETRY)) |
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mmap_read_unlock(current->mm); |
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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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no_context(regs, error_code, address); |
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return 1; |
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} |
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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_is_accessible(vma))) |
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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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vm_fault_t fault; |
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unsigned int flags = FAULT_FLAG_DEFAULT; |
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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 (kprobe_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(kprobe_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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mmap_read_lock(mm); |
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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, regs); |
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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 (fault & VM_FAULT_RETRY) { |
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flags |= FAULT_FLAG_TRIED; |
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/* |
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* No need to mmap_read_unlock(mm) 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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mmap_read_unlock(mm); |
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}
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