252 lines
6.1 KiB
C
252 lines
6.1 KiB
C
/*
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* Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
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* Licensed under the GPL
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*/
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#include "linux/kernel.h"
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#include "asm/errno.h"
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#include "linux/sched.h"
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#include "linux/mm.h"
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#include "linux/spinlock.h"
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#include "linux/config.h"
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#include "linux/init.h"
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#include "linux/ptrace.h"
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#include "asm/semaphore.h"
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#include "asm/pgtable.h"
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#include "asm/pgalloc.h"
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#include "asm/tlbflush.h"
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#include "asm/a.out.h"
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#include "asm/current.h"
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#include "asm/irq.h"
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#include "sysdep/sigcontext.h"
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#include "user_util.h"
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#include "kern_util.h"
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#include "kern.h"
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#include "chan_kern.h"
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#include "mconsole_kern.h"
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#include "mem.h"
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#include "mem_kern.h"
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#include "sysdep/sigcontext.h"
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#include "sysdep/ptrace.h"
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#include "os.h"
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#ifdef CONFIG_MODE_SKAS
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#include "skas.h"
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#endif
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#include "os.h"
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/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
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int handle_page_fault(unsigned long address, unsigned long ip,
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int is_write, int is_user, int *code_out)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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pgd_t *pgd;
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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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int err = -EFAULT;
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*code_out = SEGV_MAPERR;
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/* If the fault was during atomic operation, don't take the fault, just
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* fail. */
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if (in_atomic())
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goto out_nosemaphore;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if(!vma)
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goto out;
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else if(vma->vm_start <= address)
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goto good_area;
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else if(!(vma->vm_flags & VM_GROWSDOWN))
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goto out;
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else if(is_user && !ARCH_IS_STACKGROW(address))
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goto out;
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else if(expand_stack(vma, address))
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goto out;
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good_area:
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*code_out = SEGV_ACCERR;
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if(is_write && !(vma->vm_flags & VM_WRITE))
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goto out;
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/* Don't require VM_READ|VM_EXEC for write faults! */
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if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
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goto out;
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do {
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survive:
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switch (handle_mm_fault(mm, vma, address, is_write)){
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case VM_FAULT_MINOR:
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current->min_flt++;
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break;
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case VM_FAULT_MAJOR:
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current->maj_flt++;
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break;
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case VM_FAULT_SIGBUS:
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err = -EACCES;
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goto out;
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case VM_FAULT_OOM:
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err = -ENOMEM;
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goto out_of_memory;
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default:
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BUG();
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}
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pgd = pgd_offset(mm, address);
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pud = pud_offset(pgd, address);
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pmd = pmd_offset(pud, address);
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pte = pte_offset_kernel(pmd, address);
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} while(!pte_present(*pte));
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err = 0;
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/* The below warning was added in place of
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* pte_mkyoung(); if (is_write) pte_mkdirty();
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* If it's triggered, we'd see normally a hang here (a clean pte is
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* marked read-only to emulate the dirty bit).
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* However, the generic code can mark a PTE writable but clean on a
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* concurrent read fault, triggering this harmlessly. So comment it out.
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*/
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#if 0
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WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
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#endif
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flush_tlb_page(vma, address);
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out:
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up_read(&mm->mmap_sem);
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out_nosemaphore:
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return(err);
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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if (current->pid == 1) {
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up_read(&mm->mmap_sem);
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yield();
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down_read(&mm->mmap_sem);
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goto survive;
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}
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goto out;
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}
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void segv_handler(int sig, union uml_pt_regs *regs)
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{
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struct faultinfo * fi = UPT_FAULTINFO(regs);
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if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
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bad_segv(*fi, UPT_IP(regs));
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return;
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}
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segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
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}
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struct kern_handlers handlinfo_kern = {
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.relay_signal = relay_signal,
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.winch = winch,
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.bus_handler = relay_signal,
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.page_fault = segv_handler,
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.sigio_handler = sigio_handler,
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.timer_handler = timer_handler
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};
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/*
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* We give a *copy* of the faultinfo in the regs to segv.
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* This must be done, since nesting SEGVs could overwrite
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* the info in the regs. A pointer to the info then would
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* give us bad data!
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*/
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unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
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{
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struct siginfo si;
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void *catcher;
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int err;
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int is_write = FAULT_WRITE(fi);
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unsigned long address = FAULT_ADDRESS(fi);
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if(!is_user && (address >= start_vm) && (address < end_vm)){
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flush_tlb_kernel_vm();
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return(0);
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}
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else if(current->mm == NULL)
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panic("Segfault with no mm");
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if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
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err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
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else {
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err = -EFAULT;
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/* A thread accessed NULL, we get a fault, but CR2 is invalid.
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* This code is used in __do_copy_from_user() of TT mode. */
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address = 0;
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}
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catcher = current->thread.fault_catcher;
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if(!err)
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return(0);
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else if(catcher != NULL){
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current->thread.fault_addr = (void *) address;
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do_longjmp(catcher, 1);
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}
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else if(current->thread.fault_addr != NULL)
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panic("fault_addr set but no fault catcher");
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else if(!is_user && arch_fixup(ip, sc))
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return(0);
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if(!is_user)
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panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
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address, ip);
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if (err == -EACCES) {
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si.si_signo = SIGBUS;
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si.si_errno = 0;
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si.si_code = BUS_ADRERR;
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si.si_addr = (void __user *)address;
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current->thread.arch.faultinfo = fi;
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force_sig_info(SIGBUS, &si, current);
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} else if (err == -ENOMEM) {
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printk("VM: killing process %s\n", current->comm);
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do_exit(SIGKILL);
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} else {
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BUG_ON(err != -EFAULT);
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si.si_signo = SIGSEGV;
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si.si_addr = (void __user *) address;
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current->thread.arch.faultinfo = fi;
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force_sig_info(SIGSEGV, &si, current);
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}
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return(0);
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}
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void bad_segv(struct faultinfo fi, unsigned long ip)
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{
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struct siginfo si;
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si.si_signo = SIGSEGV;
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si.si_code = SEGV_ACCERR;
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si.si_addr = (void __user *) FAULT_ADDRESS(fi);
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current->thread.arch.faultinfo = fi;
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force_sig_info(SIGSEGV, &si, current);
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}
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void relay_signal(int sig, union uml_pt_regs *regs)
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{
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if(arch_handle_signal(sig, regs)) return;
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if(!UPT_IS_USER(regs))
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panic("Kernel mode signal %d", sig);
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current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
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force_sig(sig, current);
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}
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void bus_handler(int sig, union uml_pt_regs *regs)
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{
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if(current->thread.fault_catcher != NULL)
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do_longjmp(current->thread.fault_catcher, 1);
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else relay_signal(sig, regs);
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}
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void winch(int sig, union uml_pt_regs *regs)
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{
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do_IRQ(WINCH_IRQ, regs);
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}
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void trap_init(void)
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{
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}
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