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306 lines
6.7 KiB
306 lines
6.7 KiB
// SPDX-License-Identifier: GPL-2.0 |
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// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd. |
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#include <linux/extable.h> |
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#include <linux/kprobes.h> |
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#include <linux/mmu_context.h> |
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#include <linux/perf_event.h> |
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int fixup_exception(struct pt_regs *regs) |
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{ |
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const struct exception_table_entry *fixup; |
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fixup = search_exception_tables(instruction_pointer(regs)); |
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if (fixup) { |
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regs->pc = fixup->nextinsn; |
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return 1; |
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} |
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return 0; |
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} |
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static inline bool is_write(struct pt_regs *regs) |
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{ |
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switch (trap_no(regs)) { |
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case VEC_TLBINVALIDS: |
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return true; |
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case VEC_TLBMODIFIED: |
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return true; |
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} |
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return false; |
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} |
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#ifdef CONFIG_CPU_HAS_LDSTEX |
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static inline void csky_cmpxchg_fixup(struct pt_regs *regs) |
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{ |
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return; |
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} |
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#else |
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extern unsigned long csky_cmpxchg_ldw; |
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extern unsigned long csky_cmpxchg_stw; |
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static inline void csky_cmpxchg_fixup(struct pt_regs *regs) |
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{ |
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if (trap_no(regs) != VEC_TLBMODIFIED) |
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return; |
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if (instruction_pointer(regs) == csky_cmpxchg_stw) |
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instruction_pointer_set(regs, csky_cmpxchg_ldw); |
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return; |
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} |
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#endif |
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static inline void no_context(struct pt_regs *regs, unsigned long addr) |
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{ |
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current->thread.trap_no = trap_no(regs); |
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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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/* |
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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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pr_alert("Unable to handle kernel paging request at virtual " |
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"addr 0x%08lx, pc: 0x%08lx\n", addr, regs->pc); |
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die(regs, "Oops"); |
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do_exit(SIGKILL); |
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} |
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static inline void mm_fault_error(struct pt_regs *regs, unsigned long addr, vm_fault_t fault) |
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{ |
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current->thread.trap_no = trap_no(regs); |
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if (fault & VM_FAULT_OOM) { |
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/* |
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* We ran out of memory, call the OOM killer, and return the userspace |
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* (which will retry the fault, or kill us if we got oom-killed). |
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*/ |
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if (!user_mode(regs)) { |
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no_context(regs, addr); |
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return; |
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} |
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pagefault_out_of_memory(); |
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return; |
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} else if (fault & VM_FAULT_SIGBUS) { |
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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, addr); |
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return; |
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} |
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do_trap(regs, SIGBUS, BUS_ADRERR, addr); |
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return; |
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} |
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BUG(); |
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} |
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static inline void bad_area(struct pt_regs *regs, struct mm_struct *mm, int code, unsigned long addr) |
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{ |
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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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/* User mode accesses just cause a SIGSEGV */ |
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if (user_mode(regs)) { |
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do_trap(regs, SIGSEGV, code, addr); |
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return; |
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} |
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no_context(regs, addr); |
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} |
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static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long addr) |
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{ |
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pgd_t *pgd, *pgd_k; |
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pud_t *pud, *pud_k; |
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pmd_t *pmd, *pmd_k; |
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pte_t *pte_k; |
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int offset; |
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/* User mode accesses just cause a SIGSEGV */ |
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if (user_mode(regs)) { |
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do_trap(regs, SIGSEGV, code, addr); |
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return; |
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} |
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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 "tsk" 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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offset = pgd_index(addr); |
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pgd = get_pgd() + offset; |
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pgd_k = init_mm.pgd + offset; |
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if (!pgd_present(*pgd_k)) { |
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no_context(regs, addr); |
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return; |
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} |
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set_pgd(pgd, *pgd_k); |
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pud = (pud_t *)pgd; |
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pud_k = (pud_t *)pgd_k; |
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if (!pud_present(*pud_k)) { |
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no_context(regs, addr); |
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return; |
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} |
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pmd = pmd_offset(pud, addr); |
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pmd_k = pmd_offset(pud_k, addr); |
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if (!pmd_present(*pmd_k)) { |
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no_context(regs, addr); |
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return; |
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} |
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set_pmd(pmd, *pmd_k); |
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pte_k = pte_offset_kernel(pmd_k, addr); |
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if (!pte_present(*pte_k)) { |
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no_context(regs, addr); |
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return; |
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} |
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flush_tlb_one(addr); |
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} |
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static inline bool access_error(struct pt_regs *regs, struct vm_area_struct *vma) |
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{ |
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if (is_write(regs)) { |
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if (!(vma->vm_flags & VM_WRITE)) |
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return true; |
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} else { |
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if (unlikely(!vma_is_accessible(vma))) |
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return true; |
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} |
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return false; |
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} |
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/* |
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* This routine handles page faults. It determines the address and the |
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* problem, and then passes it off to one of the appropriate routines. |
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*/ |
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asmlinkage void do_page_fault(struct pt_regs *regs) |
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{ |
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struct task_struct *tsk; |
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struct vm_area_struct *vma; |
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struct mm_struct *mm; |
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unsigned long addr = read_mmu_entryhi() & PAGE_MASK; |
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unsigned int flags = FAULT_FLAG_DEFAULT; |
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int code = SEGV_MAPERR; |
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vm_fault_t fault; |
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tsk = current; |
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mm = tsk->mm; |
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csky_cmpxchg_fixup(regs); |
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if (kprobe_page_fault(regs, tsk->thread.trap_no)) |
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return; |
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/* |
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* Fault-in kernel-space virtual memory on-demand. |
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* The '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((addr >= VMALLOC_START) && (addr <= VMALLOC_END))) { |
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vmalloc_fault(regs, code, addr); |
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return; |
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} |
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/* Enable interrupts if they were enabled in the parent context. */ |
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if (likely(regs->sr & BIT(6))) |
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local_irq_enable(); |
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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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* in an atomic region, then we must not take the fault. |
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*/ |
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if (unlikely(faulthandler_disabled() || !mm)) { |
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no_context(regs, addr); |
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return; |
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} |
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if (user_mode(regs)) |
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flags |= FAULT_FLAG_USER; |
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); |
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if (is_write(regs)) |
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flags |= FAULT_FLAG_WRITE; |
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retry: |
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mmap_read_lock(mm); |
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vma = find_vma(mm, addr); |
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if (unlikely(!vma)) { |
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bad_area(regs, mm, code, addr); |
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return; |
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} |
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if (likely(vma->vm_start <= addr)) |
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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, mm, code, addr); |
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return; |
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} |
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if (unlikely(expand_stack(vma, addr))) { |
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bad_area(regs, mm, code, addr); |
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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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code = SEGV_ACCERR; |
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if (unlikely(access_error(regs, vma))) { |
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bad_area(regs, mm, code, addr); |
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return; |
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} |
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/* |
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* If for any reason at all we could not 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, addr, flags, regs); |
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/* |
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* If we need to retry but a fatal signal is pending, handle the |
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* signal first. We do not need to release the mmap_lock because it |
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* would already be released in __lock_page_or_retry in mm/filemap.c. |
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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, addr); |
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return; |
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} |
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if (unlikely((fault & VM_FAULT_RETRY) && (flags & FAULT_FLAG_ALLOW_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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if (unlikely(fault & VM_FAULT_ERROR)) { |
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mm_fault_error(regs, addr, fault); |
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return; |
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} |
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return; |
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}
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