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         if(page == (unsigned long) current_thread + PAGE_SIZE)
  58                 panic("Kernel stack overflow");
  59         pgd = pgd_offset(mm, page);
  60         pmd = pmd_offset(pgd, page);
  61         do {
  62  survive:
  63                 switch (handle_mm_fault(mm, vma, address, is_write)){
  64                 case VM_FAULT_MINOR:
  65                         current->min_flt++;
  66                         break;
  67                 case VM_FAULT_MAJOR:
  68                         current->maj_flt++;
  69                         break;
  70                 case VM_FAULT_SIGBUS:
  71                         err = -EACCES;
  72                         goto out;
  73                 case VM_FAULT_OOM:
  74                         err = -ENOMEM;
  75                         goto out_of_memory;
  76                 default:
  77                         BUG();
  78                 }
  79                 pte = pte_offset_kernel(pmd, page);
  80         } while(!pte_present(*pte));
  81         err = 0;
  82         *pte = pte_mkyoung(*pte);
  83         if(pte_write(*pte)) *pte = pte_mkdirty(*pte);
  84         flush_tlb_page(vma, page);
  85  out:
  86         up_read(&mm->mmap_sem);
  87         return(err);
  88
  89 /*
  90  * We ran out of memory, or some other thing happened to us that made
  91  * us unable to handle the page fault gracefully.
  92  */
  93 out_of_memory:
  94         if (current->pid == 1) {
  95                 up_read(&mm->mmap_sem);
  96                 yield();
  97                 down_read(&mm->mmap_sem);
  98                 goto survive;
  99         }
 100         goto out;
 101 }
 102
 103 LIST_HEAD(physmem_remappers);
 104
 105 void register_remapper(struct remapper *info)
 106 {
 107         list_add(&info->list, &physmem_remappers);
 108 }
 109
 110 static int check_remapped_addr(unsigned long address, int is_write, int is_user)
 111 {
 112         struct remapper *remapper;
 113         struct list_head *ele;
 114         __u64 offset;
 115         int fd;
 116
 117         fd = phys_mapping(__pa(address), &offset);
 118         if(fd == -1)
 119                 return(0);
 120
 121         list_for_each(ele, &physmem_remappers){
 122                 remapper = list_entry(ele, struct remapper, list);
 123                 if((*remapper->proc)(fd, address, is_write, offset, is_user))
 124                         return(1);
 125         }
 126
 127         return(0);
 128 }
 129
 130 unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 131                    int is_user, void *sc)
 132 {
 133         struct siginfo si;
 134         void *catcher;
 135         int err;
 136
 137         if(!is_user && (address >= start_vm) && (address < end_vm)){
 138                 flush_tlb_kernel_vm();
 139                 return(0);
 140         }
 141         else if(check_remapped_addr(address & PAGE_MASK, is_write, is_user))
 142                 return(0);
 143         else if(current->mm == NULL)
 144                 panic("Segfault with no mm");
 145         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
 146
 147         catcher = current->thread.fault_catcher;
 148         if(!err)
 149                 return(0);
 150         else if(catcher != NULL){
 151                 current->thread.fault_addr = (void *) address;
 152                 do_longjmp(catcher, 1);
 153         }
 154         else if(current->thread.fault_addr != NULL)
 155                 panic("fault_addr set but no fault catcher");
 156         else if(arch_fixup(ip, sc))
 157                 return(0);
 158
 159         if(!is_user)
 160                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
 161                       address, ip);
 162
 163         if(err == -EACCES){
 164                 si.si_signo = SIGBUS;
 165                 si.si_errno = 0;
 166                 si.si_code = BUS_ADRERR;
 167                 si.si_addr = (void *)address;
 168                 force_sig_info(SIGBUS, &si, current);
 169         }
 170         else if(err == -ENOMEM){
 171                 printk("VM: killing process %s\n", current->comm);
 172                 do_exit(SIGKILL);
 173         }
 174         else {
 175                 si.si_signo = SIGSEGV;
 176                 si.si_addr = (void *) address;
 177                 current->thread.cr2 = address;
 178                 current->thread.err = is_write;
 179                 force_sig_info(SIGSEGV, &si, current);
 180         }
 181         return(0);
 182 }
 183
 184 void bad_segv(unsigned long address, unsigned long ip, int is_write)
 185 {
 186         struct siginfo si;
 187
 188         si.si_signo = SIGSEGV;
 189         si.si_code = SEGV_ACCERR;
 190         si.si_addr = (void *) address;
 191         current->thread.cr2 = address;
 192         current->thread.err = is_write;
 193         force_sig_info(SIGSEGV, &si, current);
 194 }
 195
 196 void relay_signal(int sig, union uml_pt_regs *regs)
 197 {
 198         if(arch_handle_signal(sig, regs)) return;
 199         if(!UPT_IS_USER(regs))
 200                 panic("Kernel mode signal %d", sig);
 201         force_sig(sig, current);
 202 }
 203
 204 void bus_handler(int sig, union uml_pt_regs *regs)
 205 {
 206         if(current->thread.fault_catcher != NULL)
 207                 do_longjmp(current->thread.fault_catcher, 1);
 208         else relay_signal(sig, regs);
 209 }
 210
 211 void winch(int sig, union uml_pt_regs *regs)
 212 {
 213         do_IRQ(WINCH_IRQ, regs);
 214 }
 215
 216 void trap_init(void)
 217 {
 218 }
 219
 220 spinlock_t trap_lock = SPIN_LOCK_UNLOCKED;
 221
 222 static int trap_index = 0;
 223
 224 int next_trap_index(int limit)
 225 {
 226         int ret;
 227
 228         spin_lock(&trap_lock);
 229         ret = trap_index;
 230         if(++trap_index == limit)
 231                 trap_index = 0;
 232         spin_unlock(&trap_lock);
 233         return(ret);
 234 }
 235
 236 /*
 237  * Overrides for Emacs so that we follow Linus's tabbing style.
 238  * Emacs will notice this stuff at the end of the file and automatically
 239  * adjust the settings for this buffer only.  This must remain at the end
 240  * of the file.
 241  * ---------------------------------------------------------------------------
 242  * Local variables:
 243  * c-file-style: "linux"
 244  * End:
 245  */