![Peter Xu](/assets/img/avatar_default.png)
Use the general page fault accounting by passing regs into handle_mm_fault(). It naturally solve the issue of multiple page fault accounting when page fault retry happened. Fix PERF_COUNT_SW_PAGE_FAULTS perf event manually for page fault retries, by moving it before taking mmap_sem. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Vineet Gupta <vgupta@synopsys.com> Link: http://lkml.kernel.org/r/20200707225021.200906-4-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
189 lines
4.2 KiB
C
189 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Page Fault Handling for ARC (TLB Miss / ProtV)
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*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*/
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#include <linux/signal.h>
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#include <linux/interrupt.h>
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#include <linux/sched/signal.h>
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#include <linux/errno.h>
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#include <linux/ptrace.h>
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#include <linux/uaccess.h>
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#include <linux/kdebug.h>
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#include <linux/perf_event.h>
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#include <linux/mm_types.h>
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#include <asm/mmu.h>
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/*
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* kernel virtual address is required to implement vmalloc/pkmap/fixmap
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* Refer to asm/processor.h for System Memory Map
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*
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* It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
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* from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
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*/
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noinline static int handle_kernel_vaddr_fault(unsigned long address)
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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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pgd_t *pgd, *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 = pgd_offset_fast(current->active_mm, address);
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pgd_k = pgd_offset_k(address);
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if (!pgd_present(*pgd_k))
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goto bad_area;
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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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goto bad_area;
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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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goto bad_area;
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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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goto bad_area;
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set_pmd(pmd, *pmd_k);
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/* XXX: create the TLB entry here */
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return 0;
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bad_area:
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return 1;
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}
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void do_page_fault(unsigned long address, struct pt_regs *regs)
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{
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struct vm_area_struct *vma = NULL;
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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int sig, si_code = SEGV_MAPERR;
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unsigned int write = 0, exec = 0, mask;
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vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
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unsigned int flags; /* handle_mm_fault() input */
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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 (address >= VMALLOC_START && !user_mode(regs)) {
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if (unlikely(handle_kernel_vaddr_fault(address)))
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goto no_context;
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else
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return;
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}
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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if (faulthandler_disabled() || !mm)
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goto no_context;
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if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
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write = 1;
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else if ((regs->ecr_vec == ECR_V_PROTV) &&
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(regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
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exec = 1;
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flags = FAULT_FLAG_DEFAULT;
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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if (write)
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flags |= FAULT_FLAG_WRITE;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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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 (!vma)
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goto bad_area;
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if (unlikely(address < vma->vm_start)) {
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if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
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goto bad_area;
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}
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/*
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* vm_area is good, now check permissions for this memory access
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*/
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mask = VM_READ;
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if (write)
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mask = VM_WRITE;
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if (exec)
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mask = VM_EXEC;
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if (!(vma->vm_flags & mask)) {
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si_code = SEGV_ACCERR;
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goto bad_area;
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}
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fault = handle_mm_fault(vma, address, flags, regs);
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/* Quick path to respond to signals */
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if (fault_signal_pending(fault, regs)) {
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if (!user_mode(regs))
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goto no_context;
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return;
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}
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/*
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* Fault retry nuances, mmap_lock already relinquished by core mm
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*/
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if (unlikely((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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goto retry;
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}
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bad_area:
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mmap_read_unlock(mm);
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/*
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* Major/minor page fault accounting
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* (in case of retry we only land here once)
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*/
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if (likely(!(fault & VM_FAULT_ERROR)))
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/* Normal return path: fault Handled Gracefully */
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return;
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if (!user_mode(regs))
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goto no_context;
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if (fault & VM_FAULT_OOM) {
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pagefault_out_of_memory();
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return;
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}
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if (fault & VM_FAULT_SIGBUS) {
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sig = SIGBUS;
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si_code = BUS_ADRERR;
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}
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else {
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sig = SIGSEGV;
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}
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tsk->thread.fault_address = address;
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force_sig_fault(sig, si_code, (void __user *)address);
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return;
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no_context:
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if (fixup_exception(regs))
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return;
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die("Oops", regs, address);
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}
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