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                         if (current->pid == 1) {
  78                                 up_read(&mm->mmap_sem);
  79                                 yield();
  80                                 down_read(&mm->mmap_sem);
  81                                 goto survive;
  82                         }
  83                         goto out;
  84                 }
  85                 pte = pte_offset_kernel(pmd, page);
  86         } while(!pte_present(*pte));
  87         err = 0;
  88         *pte = pte_mkyoung(*pte);
  89         if(pte_write(*pte)) *pte = pte_mkdirty(*pte);
  90         flush_tlb_page(vma, page);
  91  out:
  92         up_read(&mm->mmap_sem);
  93         return(err);
  94
  95 /*
  96  * We ran out of memory, or some other thing happened to us that made
  97  * us unable to handle the page fault gracefully.
  98  */
  99 out_of_memory:
 100         if (current->pid == 1) {
 101                 up_read(&mm->mmap_sem);
 102                 yield();
 103                 down_read(&mm->mmap_sem);
 104                 goto survive;
 105         }
 106         err = -ENOMEM;
 107         goto out;
 108 }
 109
 110 LIST_HEAD(physmem_remappers);
 111
 112 void register_remapper(struct remapper *info)
 113 {
 114         list_add(&info->list, &physmem_remappers);
 115 }
 116
 117 static int check_remapped_addr(unsigned long address, int is_write)
 118 {
 119         struct remapper *remapper;
 120         struct list_head *ele;
 121         __u64 offset;
 122         int fd;
 123
 124         fd = phys_mapping(__pa(address), &offset);
 125         if(fd == -1)
 126                 return(0);
 127
 128         list_for_each(ele, &physmem_remappers){
 129                 remapper = list_entry(ele, struct remapper, list);
 130                 if((*remapper->proc)(fd, address, is_write, offset))
 131                         return(1);
 132         }
 133
 134         return(0);
 135 }
 136
 137 unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 138                    int is_user, void *sc)
 139 {
 140         struct siginfo si;
 141         void *catcher;
 142         int err;
 143
 144         if(!is_user && (address >= start_vm) && (address < end_vm)){
 145                 flush_tlb_kernel_vm();
 146                 return(0);
 147         }
 148         else if(check_remapped_addr(address & PAGE_MASK, is_write))
 149                 return(0);
 150         else if(current->mm == NULL)
 151                 panic("Segfault with no mm");
 152         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
 153
 154         catcher = current->thread.fault_catcher;
 155         if(!err)
 156                 return(0);
 157         else if(catcher != NULL){
 158                 current->thread.fault_addr = (void *) address;
 159                 do_longjmp(catcher, 1);
 160         }
 161         else if(current->thread.fault_addr != NULL)
 162                 panic("fault_addr set but no fault catcher");
 163         else if(arch_fixup(ip, sc))
 164                 return(0);
 165
 166         if(!is_user)
 167                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
 168                       address, ip);
 169
 170         if(err == -EACCES){
 171                 si.si_signo = SIGBUS;
 172                 si.si_errno = 0;
 173                 si.si_code = BUS_ADRERR;
 174                 si.si_addr = (void *)address;
 175                 force_sig_info(SIGBUS, &si, current);
 176         }
 177         else if(err == -ENOMEM){
 178                 printk("VM: killing process %s\n", current->comm);
 179                 do_exit(SIGKILL);
 180         }
 181         else {
 182                 si.si_signo = SIGSEGV;
 183                 si.si_addr = (void *) address;
 184                 current->thread.cr2 = address;
 185                 current->thread.err = is_write;
 186                 force_sig_info(SIGSEGV, &si, current);
 187         }
 188         return(0);
 189 }
 190
 191 void bad_segv(unsigned long address, unsigned long ip, int is_write)
 192 {
 193         struct siginfo si;
 194
 195         si.si_signo = SIGSEGV;
 196         si.si_code = SEGV_ACCERR;
 197         si.si_addr = (void *) address;
 198         current->thread.cr2 = address;
 199         current->thread.err = is_write;
 200         force_sig_info(SIGSEGV, &si, current);
 201 }
 202
 203 void relay_signal(int sig, union uml_pt_regs *regs)
 204 {
 205         if(arch_handle_signal(sig, regs)) return;
 206         if(!UPT_IS_USER(regs))
 207                 panic("Kernel mode signal %d", sig);
 208         force_sig(sig, current);
 209 }
 210
 211 void bus_handler(int sig, union uml_pt_regs *regs)
 212 {
 213         if(current->thread.fault_catcher != NULL)
 214                 do_longjmp(current->thread.fault_catcher, 1);
 215         else relay_signal(sig, regs);
 216 }
 217
 218 void winch(int sig, union uml_pt_regs *regs)
 219 {
 220         do_IRQ(WINCH_IRQ, regs);
 221 }
 222
 223 void trap_init(void)
 224 {
 225 }
 226
 227 spinlock_t trap_lock = SPIN_LOCK_UNLOCKED;
 228
 229 static int trap_index = 0;
 230
 231 int next_trap_index(int limit)
 232 {
 233         int ret;
 234
 235         spin_lock(&trap_lock);
 236         ret = trap_index;
 237         if(++trap_index == limit)
 238                 trap_index = 0;
 239         spin_unlock(&trap_lock);
 240         return(ret);
 241 }
 242
 243 /*
 244  * Overrides for Emacs so that we follow Linus's tabbing style.
 245  * Emacs will notice this stuff at the end of the file and automatically
 246  * adjust the settings for this buffer only.  This must remain at the end
 247  * of the file.
 248  * ---------------------------------------------------------------------------
 249  * Local variables:
 250  * c-file-style: "linux"
 251  * End:
 252  */