forked from Minki/linux
f3f09d5a44
Commitd065bd810b(mm: retry page fault when blocking on disk transfer) and commit37b23e0525(x86,mm: make pagefault killable) The above commits introduced changes into the x86 pagefault handler for making the page fault handler retryable as well as killable. These changes reduce the mmap_sem hold time, which is crucial during OOM killer invocation. Port these changes to unicore32. Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
496 lines
12 KiB
C
496 lines
12 KiB
C
/*
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* linux/arch/unicore32/mm/fault.c
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*
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* Code specific to PKUnity SoC and UniCore ISA
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*
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* Copyright (C) 2001-2010 GUAN Xue-tao
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/signal.h>
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#include <linux/mm.h>
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#include <linux/hardirq.h>
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#include <linux/init.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <linux/page-flags.h>
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#include <linux/sched.h>
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#include <linux/io.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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/*
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* Fault status register encodings. We steal bit 31 for our own purposes.
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*/
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#define FSR_LNX_PF (1 << 31)
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static inline int fsr_fs(unsigned int fsr)
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{
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/* xyabcde will be abcde+xy */
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return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
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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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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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mm = &init_mm;
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printk(KERN_ALERT "pgd = %p\n", mm->pgd);
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pgd = pgd_offset(mm, addr);
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printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
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do {
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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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pmd = pmd_offset((pud_t *) pgd, addr);
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if (PTRS_PER_PMD != 1)
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printk(", *pmd=%08lx", 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_map(pmd, addr);
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printk(", *pte=%08lx", pte_val(*pte));
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pte_unmap(pte);
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} while (0);
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printk("\n");
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}
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/*
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* Oops. The kernel tried to access some page that wasn't present.
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*/
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static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
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unsigned int fsr, struct pt_regs *regs)
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{
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/*
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* Are we prepared to handle this kernel fault?
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*/
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if (fixup_exception(regs))
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return;
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/*
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* No handler, we'll have to terminate things with extreme prejudice.
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*/
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bust_spinlocks(1);
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printk(KERN_ALERT
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"Unable to handle kernel %s at virtual address %08lx\n",
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(addr < PAGE_SIZE) ? "NULL pointer dereference" :
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"paging request", addr);
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show_pte(mm, addr);
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die("Oops", regs, fsr);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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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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* User mode accesses just cause a SIGSEGV
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*/
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static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
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unsigned int fsr, unsigned int sig, int code,
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struct pt_regs *regs)
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{
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struct siginfo si;
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tsk->thread.address = addr;
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tsk->thread.error_code = fsr;
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tsk->thread.trap_no = 14;
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si.si_signo = sig;
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si.si_errno = 0;
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si.si_code = code;
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si.si_addr = (void __user *)addr;
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force_sig_info(sig, &si, tsk);
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}
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void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->active_mm;
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/*
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* If we are in kernel mode at this point, we
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* have no context to handle this fault with.
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*/
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if (user_mode(regs))
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__do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
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else
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__do_kernel_fault(mm, addr, fsr, regs);
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}
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#define VM_FAULT_BADMAP 0x010000
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#define VM_FAULT_BADACCESS 0x020000
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/*
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* Check that the permissions on the VMA allow for the fault which occurred.
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* If we encountered a write fault, we must have write permission, otherwise
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* we allow any permission.
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*/
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static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
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{
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unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
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if (!(fsr ^ 0x12)) /* write? */
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mask = VM_WRITE;
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if (fsr & FSR_LNX_PF)
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mask = VM_EXEC;
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return vma->vm_flags & mask ? false : true;
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}
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static int __do_pf(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
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unsigned int flags, struct task_struct *tsk)
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{
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struct vm_area_struct *vma;
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int fault;
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vma = find_vma(mm, addr);
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fault = VM_FAULT_BADMAP;
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if (unlikely(!vma))
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goto out;
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if (unlikely(vma->vm_start > addr))
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goto check_stack;
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/*
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* Ok, we have a good vm_area for this
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* memory access, so we can handle it.
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*/
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good_area:
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if (access_error(fsr, vma)) {
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fault = VM_FAULT_BADACCESS;
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goto out;
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}
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/*
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* If for any reason at all we couldn't handle the fault, make
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* sure we exit gracefully rather than endlessly redo the fault.
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*/
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fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
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return fault;
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check_stack:
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if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
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goto good_area;
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out:
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return fault;
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}
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static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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int fault, sig, code;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
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((!(fsr ^ 0x12)) ? FAULT_FLAG_WRITE : 0);
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tsk = current;
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mm = tsk->mm;
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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 (in_atomic() || !mm)
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goto no_context;
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/*
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* As per x86, we may deadlock here. However, since the kernel only
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* validly references user space from well defined areas of the code,
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* we can bug out early if this is from code which shouldn't.
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*/
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if (!down_read_trylock(&mm->mmap_sem)) {
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if (!user_mode(regs)
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&& !search_exception_tables(regs->UCreg_pc))
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goto no_context;
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retry:
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down_read(&mm->mmap_sem);
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} else {
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/*
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* The above down_read_trylock() might have succeeded in
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* which case, we'll have missed the might_sleep() from
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* down_read()
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*/
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might_sleep();
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#ifdef CONFIG_DEBUG_VM
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if (!user_mode(regs) &&
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!search_exception_tables(regs->UCreg_pc))
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goto no_context;
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#endif
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}
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fault = __do_pf(mm, addr, fsr, flags, tsk);
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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_sem because
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* it would already be released in __lock_page_or_retry in
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* mm/filemap.c. */
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return 0;
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if (!(fault & VM_FAULT_ERROR) && (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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else
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tsk->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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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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* Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
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*/
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if (likely(!(fault &
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(VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
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return 0;
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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 to
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* userspace (which will retry the fault, or kill us if we
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* got oom-killed)
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*/
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pagefault_out_of_memory();
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return 0;
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}
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/*
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* If we are in kernel mode at this point, we
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* have no context to handle this fault with.
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*/
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if (!user_mode(regs))
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goto no_context;
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if (fault & VM_FAULT_SIGBUS) {
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/*
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* We had some memory, but were unable to
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* successfully fix up this page fault.
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*/
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sig = SIGBUS;
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code = BUS_ADRERR;
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} else {
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/*
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* Something tried to access memory that
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* isn't in our memory map..
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*/
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sig = SIGSEGV;
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code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
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}
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__do_user_fault(tsk, addr, fsr, sig, code, regs);
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return 0;
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no_context:
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__do_kernel_fault(mm, addr, fsr, regs);
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return 0;
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}
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/*
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* First Level Translation Fault Handler
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*
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* We enter here because the first level page table doesn't contain
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* a valid entry for the address.
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*
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* If the address is in kernel space (>= TASK_SIZE), then we are
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* probably faulting in the vmalloc() area.
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*
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* If the init_task's first level page tables contains the relevant
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* entry, we copy the it to this task. If not, we send the process
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* a signal, fixup the exception, or oops the kernel.
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*
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* NOTE! We MUST NOT take any locks for this case. We may be in an
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* interrupt or a critical region, and should only copy the information
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* from the master page table, nothing more.
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*/
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static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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unsigned int index;
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pgd_t *pgd, *pgd_k;
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pmd_t *pmd, *pmd_k;
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if (addr < TASK_SIZE)
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return do_pf(addr, fsr, regs);
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if (user_mode(regs))
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goto bad_area;
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index = pgd_index(addr);
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pgd = cpu_get_pgd() + index;
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pgd_k = init_mm.pgd + index;
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if (pgd_none(*pgd_k))
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goto bad_area;
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pmd_k = pmd_offset((pud_t *) pgd_k, addr);
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pmd = pmd_offset((pud_t *) pgd, addr);
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if (pmd_none(*pmd_k))
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goto bad_area;
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set_pmd(pmd, *pmd_k);
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flush_pmd_entry(pmd);
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return 0;
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bad_area:
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do_bad_area(addr, fsr, regs);
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return 0;
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}
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/*
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* This abort handler always returns "fault".
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*/
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static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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return 1;
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}
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static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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unsigned int res1, res2;
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printk("dabt exception but no error!\n");
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__asm__ __volatile__(
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"mff %0,f0\n"
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"mff %1,f1\n"
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: "=r"(res1), "=r"(res2)
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:
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: "memory");
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printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2);
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panic("shut up\n");
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return 0;
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}
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static struct fsr_info {
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int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
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int sig;
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int code;
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const char *name;
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} fsr_info[] = {
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/*
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* The following are the standard Unicore-I and UniCore-II aborts.
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*/
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{ do_good, SIGBUS, 0, "no error" },
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{ do_bad, SIGBUS, BUS_ADRALN, "alignment exception" },
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{ do_bad, SIGBUS, BUS_OBJERR, "external exception" },
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{ do_bad, SIGBUS, 0, "burst operation" },
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{ do_bad, SIGBUS, 0, "unknown 00100" },
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{ do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"},
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{ do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" },
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{ do_bad, SIGBUS, 0, "invalid pte" },
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{ do_pf, SIGSEGV, SEGV_MAPERR, "page miss" },
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{ do_bad, SIGBUS, 0, "middle page miss" },
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{ do_bad, SIGBUS, 0, "large page miss" },
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{ do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" },
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{ do_bad, SIGBUS, 0, "unknown 01100" },
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{ do_bad, SIGBUS, 0, "unknown 01101" },
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{ do_bad, SIGBUS, 0, "unknown 01110" },
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{ do_bad, SIGBUS, 0, "unknown 01111" },
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{ do_bad, SIGBUS, 0, "addr: up 3G or IO" },
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{ do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" },
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{ do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"},
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{ do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"},
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{ do_bad, SIGBUS, 0, "unknown 10100" },
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{ do_bad, SIGBUS, 0, "unknown 10101" },
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{ do_bad, SIGBUS, 0, "unknown 10110" },
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{ do_bad, SIGBUS, 0, "unknown 10111" },
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{ do_bad, SIGBUS, 0, "unknown 11000" },
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{ do_bad, SIGBUS, 0, "unknown 11001" },
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{ do_bad, SIGBUS, 0, "unknown 11010" },
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{ do_bad, SIGBUS, 0, "unknown 11011" },
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{ do_bad, SIGBUS, 0, "unknown 11100" },
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{ do_bad, SIGBUS, 0, "unknown 11101" },
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{ do_bad, SIGBUS, 0, "unknown 11110" },
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{ do_bad, SIGBUS, 0, "unknown 11111" }
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};
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void __init hook_fault_code(int nr,
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int (*fn) (unsigned long, unsigned int, struct pt_regs *),
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int sig, int code, const char *name)
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{
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if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
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BUG();
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fsr_info[nr].fn = fn;
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fsr_info[nr].sig = sig;
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fsr_info[nr].code = code;
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fsr_info[nr].name = name;
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}
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/*
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* Dispatch a data abort to the relevant handler.
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*/
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asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
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struct pt_regs *regs)
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{
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const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
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struct siginfo info;
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if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
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return;
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printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
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inf->name, fsr, addr);
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info.si_signo = inf->sig;
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info.si_errno = 0;
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info.si_code = inf->code;
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info.si_addr = (void __user *)addr;
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uc32_notify_die("", regs, &info, fsr, 0);
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}
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asmlinkage void do_PrefetchAbort(unsigned long addr,
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unsigned int ifsr, struct pt_regs *regs)
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{
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const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
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struct siginfo info;
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if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
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return;
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printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
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inf->name, ifsr, addr);
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info.si_signo = inf->sig;
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info.si_errno = 0;
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info.si_code = inf->code;
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info.si_addr = (void __user *)addr;
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uc32_notify_die("", regs, &info, ifsr, 0);
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}
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