cregit-Linux how code gets into the kernel

Release 4.7 arch/score/mm/fault.c

Directory: arch/score/mm
/*
 * arch/score/mm/fault.c
 *
 * Score Processor version.
 *
 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
 *  Lennox Wu <lennox.wu@sunplusct.com>
 *  Chen Liqin <liqin.chen@sunplusct.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>

/*
 * This routine handles page faults.  It determines the address,
 * and the problem, and then passes it off to one of the appropriate
 * routines.
 */

asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write, unsigned long address) { struct vm_area_struct *vma = NULL; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; const int field = sizeof(unsigned long) * 2; unsigned long flags = 0; siginfo_t info; int fault; info.si_code = SEGV_MAPERR; /* * We fault-in kernel-space virtual memory on-demand. The * 'reference' page table is init_mm.pgd. * * NOTE! We MUST NOT take any locks for this case. We may * be in an interrupt or a critical region, and should * only copy the information from the master page table, * nothing more. */ if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) goto vmalloc_fault; #ifdef MODULE_START if (unlikely(address >= MODULE_START && address < MODULE_END)) goto vmalloc_fault; #endif /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (pagefault_disabled() || !mm) goto bad_area_nosemaphore; if (user_mode(regs)) flags |= FAULT_FLAG_USER; down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) goto bad_area; if (vma->vm_start <= address) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; if (expand_stack(vma, address)) goto bad_area; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: info.si_code = SEGV_ACCERR; if (write) { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; flags |= FAULT_FLAG_WRITE; } else { if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) goto bad_area; } /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ fault = handle_mm_fault(mm, vma, address, flags); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) goto out_of_memory; else if (fault & VM_FAULT_SIGSEGV) goto bad_area; else if (fault & VM_FAULT_SIGBUS) goto do_sigbus; BUG(); } if (fault & VM_FAULT_MAJOR) tsk->maj_flt++; else tsk->min_flt++; up_read(&mm->mmap_sem); return; /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ bad_area: up_read(&mm->mmap_sem); bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (user_mode(regs)) { tsk->thread.cp0_badvaddr = address; tsk->thread.error_code = write; info.si_signo = SIGSEGV; info.si_errno = 0; /* info.si_code has been set above */ info.si_addr = (void __user *) address; force_sig_info(SIGSEGV, &info, tsk); return; } no_context: /* Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) { current->thread.cp0_baduaddr = address; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ bust_spinlocks(1); printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", 0, field, address, field, regs->cp0_epc, field, regs->regs[3]); die("Oops", regs); /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. */ out_of_memory: up_read(&mm->mmap_sem); if (!user_mode(regs)) goto no_context; pagefault_out_of_memory(); return; do_sigbus: up_read(&mm->mmap_sem); /* Kernel mode? Handle exceptions or die */ if (!user_mode(regs)) goto no_context; else /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ tsk->thread.cp0_badvaddr = address; info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = BUS_ADRERR; info.si_addr = (void __user *) address; force_sig_info(SIGBUS, &info, tsk); return; vmalloc_fault: { /* * Synchronize this task's top level page-table * with the 'reference' page table. * * Do _not_ use "tsk" here. We might be inside * an interrupt in the middle of a task switch.. */ int offset = __pgd_offset(address); pgd_t *pgd, *pgd_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; pte_t *pte_k; pgd = (pgd_t *) pgd_current + offset; pgd_k = init_mm.pgd + offset; if (!pgd_present(*pgd_k)) goto no_context; set_pgd(pgd, *pgd_k); pud = pud_offset(pgd, address); pud_k = pud_offset(pgd_k, address); if (!pud_present(*pud_k)) goto no_context; pmd = pmd_offset(pud, address); pmd_k = pmd_offset(pud_k, address); if (!pmd_present(*pmd_k)) goto no_context; set_pmd(pmd, *pmd_k); pte_k = pte_offset_kernel(pmd_k, address); if (!pte_present(*pte_k)) goto no_context; return; } }

Contributors

PersonTokensPropCommitsCommitProp
chen liqinchen liqin69694.82%120.00%
johannes weinerjohannes weiner273.68%240.00%
linus torvaldslinus torvalds101.36%120.00%
david hildenbranddavid hildenbrand10.14%120.00%
Total734100.00%5100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
chen liqinchen liqin73194.69%120.00%
johannes weinerjohannes weiner273.50%240.00%
linus torvaldslinus torvalds101.30%120.00%
david hildenbranddavid hildenbrand40.52%120.00%
Total772100.00%5100.00%
Directory: arch/score/mm
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