arch/um/kernel/trap_kern.c

   1 /*
   2  * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/kernel.h"
   7 #include "asm/errno.h"
   8 #include "linux/sched.h"
   9 #include "linux/mm.h"
  10 #include "linux/spinlock.h"
  11 #include "linux/config.h"
  12 #include "linux/init.h"
  13 #include "linux/ptrace.h"
  14 #include "asm/semaphore.h"
  15 #include "asm/pgtable.h"
  16 #include "asm/tlbflush.h"
  17 #include "asm/a.out.h"
  18 #include "asm/current.h"
  19 #include "asm/irq.h"
  20 #include "user_util.h"
  21 #include "kern_util.h"
  22 #include "kern.h"
  23 #include "chan_kern.h"
  24 #include "mconsole_kern.h"
  25 #include "2_5compat.h"
  26 #include "mem.h"
  27 #include "mem_kern.h"
  28
  29 int handle_page_fault(unsigned long address, unsigned long ip,
  30                       int is_write, int is_user, int *code_out)
  31 {
  32         struct mm_struct *mm = current->mm;
  33         struct vm_area_struct *vma;
  34         pgd_t *pgd;
  35         pmd_t *pmd;
  36         pte_t *pte;
  37         unsigned long page;
  38         int err = -EFAULT;
  39
  40         *code_out = SEGV_MAPERR;
  41         down_read(&mm->mmap_sem);
  42         vma = find_vma(mm, address);
  43         if(!vma)
  44                 goto out;
  45         else if(vma->vm_start <= address)
  46                 goto good_area;
  47         else if(!(vma->vm_flags & VM_GROWSDOWN))
  48                 goto out;
  49         else if(expand_stack(vma, address))
  50                 goto out;
  51
  52  good_area:
  53         *code_out = SEGV_ACCERR;
  54         if(is_write && !(vma->vm_flags & VM_WRITE))
  55                 goto out;
  56         page = address & PAGE_MASK;
  57         pgd = pgd_offset(mm, page);
  58         pmd = pmd_offset(pgd, page);
  59         do {
  60  survive:
  61                 switch (handle_mm_fault(mm, vma, address, is_write)){
  62                 case VM_FAULT_MINOR:
  63                         current->min_flt++;
  64                         break;
  65                 case VM_FAULT_MAJOR:
  66                         current->maj_flt++;
  67                         break;
  68                 case VM_FAULT_SIGBUS:
  69                         err = -EACCES;
  70                         goto out;
  71                 case VM_FAULT_OOM:
  72                         err = -ENOMEM;
  73                         goto out_of_memory;
  74                 default:
  75                         BUG();
  76                 }
  77                 pte = pte_offset_kernel(pmd, page);
  78         } while(!pte_present(*pte));
  79         err = 0;
  80         *pte = pte_mkyoung(*pte);
  81         if(pte_write(*pte)) *pte = pte_mkdirty(*pte);
  82         flush_tlb_page(vma, page);
  83  out:
  84         up_read(&mm->mmap_sem);
  85         return(err);
  86
  87 /*
  88  * We ran out of memory, or some other thing happened to us that made
  89  * us unable to handle the page fault gracefully.
  90  */
  91 out_of_memory:
  92         if (current->pid == 1) {
  93                 up_read(&mm->mmap_sem);
  94                 yield();
  95                 down_read(&mm->mmap_sem);
  96                 goto survive;
  97         }
  98         goto out;
  99 }
 100
 101 LIST_HEAD(physmem_remappers);
 102
 103 void register_remapper(struct remapper *info)
 104 {
 105         list_add(&info->list, &physmem_remappers);
 106 }
 107
 108 static int check_remapped_addr(unsigned long address, int is_write)
 109 {
 110         struct remapper *remapper;
 111         struct list_head *ele;
 112         __u64 offset;
 113         int fd;
 114
 115         fd = phys_mapping(__pa(address), &offset);
 116         if(fd == -1)
 117                 return(0);
 118
 119         list_for_each(ele, &physmem_remappers){
 120                 remapper = list_entry(ele, struct remapper, list);
 121                 if((*remapper->proc)(fd, address, is_write, offset))
 122                         return(1);
 123         }
 124
 125         return(0);
 126 }
 127
 128 unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 129                    int is_user, void *sc)
 130 {
 131         struct siginfo si;
 132         void *catcher;
 133         int err;
 134
 135         if(!is_user && (address >= start_vm) && (address < end_vm)){
 136                 flush_tlb_kernel_vm();
 137                 return(0);
 138         }
 139         else if(check_remapped_addr(address & PAGE_MASK, is_write))
 140                 return(0);
 141         else if(current->mm == NULL)
 142                 panic("Segfault with no mm");
 143         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
 144
 145         catcher = current->thread.fault_catcher;
 146         if(!err)
 147                 return(0);
 148         else if(catcher != NULL){
 149                 current->thread.fault_addr = (void *) address;
 150                 do_longjmp(catcher, 1);
 151         }
 152         else if(current->thread.fault_addr != NULL)
 153                 panic("fault_addr set but no fault catcher");
 154         else if(arch_fixup(ip, sc))
 155                 return(0);
 156
 157         if(!is_user)
 158                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
 159                       address, ip);
 160
 161         if(err == -EACCES){
 162                 si.si_signo = SIGBUS;
 163                 si.si_errno = 0;
 164                 si.si_code = BUS_ADRERR;
 165                 si.si_addr = (void *)address;
 166                 force_sig_info(SIGBUS, &si, current);
 167         }
 168         else if(err == -ENOMEM){
 169                 printk("VM: killing process %s\n", current->comm);
 170                 do_exit(SIGKILL);
 171         }
 172         else {
 173                 si.si_signo = SIGSEGV;
 174                 si.si_addr = (void *) address;
 175                 current->thread.cr2 = address;
 176                 current->thread.err = is_write;
 177                 force_sig_info(SIGSEGV, &si, current);
 178         }
 179         return(0);
 180 }
 181
 182 void bad_segv(unsigned long address, unsigned long ip, int is_write)
 183 {
 184         struct siginfo si;
 185
 186         si.si_signo = SIGSEGV;
 187         si.si_code = SEGV_ACCERR;
 188         si.si_addr = (void *) address;
 189         current->thread.cr2 = address;
 190         current->thread.err = is_write;
 191         force_sig_info(SIGSEGV, &si, current);
 192 }
 193
 194 void relay_signal(int sig, union uml_pt_regs *regs)
 195 {
 196         if(arch_handle_signal(sig, regs)) return;
 197         if(!UPT_IS_USER(regs))
 198                 panic("Kernel mode signal %d", sig);
 199         force_sig(sig, current);
 200 }
 201
 202 void bus_handler(int sig, union uml_pt_regs *regs)
 203 {
 204         if(current->thread.fault_catcher != NULL)
 205                 do_longjmp(current->thread.fault_catcher, 1);
 206         else relay_signal(sig, regs);
 207 }
 208
 209 void winch(int sig, union uml_pt_regs *regs)
 210 {
 211         do_IRQ(WINCH_IRQ, regs);
 212 }
 213
 214 void trap_init(void)
 215 {
 216 }
 217
 218 spinlock_t trap_lock = SPIN_LOCK_UNLOCKED;
 219
 220 static int trap_index = 0;
 221
 222 int next_trap_index(int limit)
 223 {
 224         int ret;
 225
 226         spin_lock(&trap_lock);
 227         ret = trap_index;
 228         if(++trap_index == limit)
 229                 trap_index = 0;
 230         spin_unlock(&trap_lock);
 231         return(ret);
 232 }
 233
 234 /*
 235  * Overrides for Emacs so that we follow Linus's tabbing style.
 236  * Emacs will notice this stuff at the end of the file and automatically
 237  * adjust the settings for this buffer only.  This must remain at the end
 238  * of the file.
 239  * ---------------------------------------------------------------------------
 240  * Local variables:
 241  * c-file-style: "linux"
 242  * End:
 243  */