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/pgalloc.h"
  17 #include "asm/tlbflush.h"
  18 #include "asm/a.out.h"
  19 #include "asm/current.h"
  20 #include "asm/irq.h"
  21 #include "user_util.h"
  22 #include "kern_util.h"
  23 #include "kern.h"
  24 #include "chan_kern.h"
  25 #include "mconsole_kern.h"
  26 #include "2_5compat.h"
  27 #include "mem.h"
  28 #include "mem_kern.h"
  29
  30 int handle_page_fault(unsigned long address, unsigned long ip,
  31                       int is_write, int is_user, int *code_out)
  32 {
  33         struct mm_struct *mm = current->mm;
  34         struct vm_area_struct *vma;
  35         pgd_t *pgd;
  36         pud_t *pud;
  37         pmd_t *pmd;
  38         pte_t *pte;
  39         unsigned long page;
  40         int err = -EFAULT;
  41
  42         *code_out = SEGV_MAPERR;
  43         down_read(&mm->mmap_sem);
  44         vma = find_vma(mm, address);
  45         if(!vma)
  46                 goto out;
  47         else if(vma->vm_start <= address)
  48                 goto good_area;
  49         else if(!(vma->vm_flags & VM_GROWSDOWN))
  50                 goto out;
  51         else if(!ARCH_IS_STACKGROW(address))
  52                 goto out;
  53         else if(expand_stack(vma, address))
  54                 goto out;
  55
  56  good_area:
  57         *code_out = SEGV_ACCERR;
  58         if(is_write && !(vma->vm_flags & VM_WRITE))
  59                 goto out;
  60         page = address & PAGE_MASK;
  61         pgd = pgd_offset(mm, page);
  62         pud = pud_offset(pgd, page);
  63         pmd = pmd_offset(pud, page);
  64         do {
  65  survive:
  66                 switch (handle_mm_fault(mm, vma, address, is_write)){
  67                 case VM_FAULT_MINOR:
  68                         current->min_flt++;
  69                         break;
  70                 case VM_FAULT_MAJOR:
  71                         current->maj_flt++;
  72                         break;
  73                 case VM_FAULT_SIGBUS:
  74                         err = -EACCES;
  75                         goto out;
  76                 case VM_FAULT_OOM:
  77                         err = -ENOMEM;
  78                         goto out_of_memory;
  79                 default:
  80                         BUG();
  81                 }
  82                 pgd = pgd_offset(mm, page);
  83                 pud = pud_offset(pgd, page);
  84                 pmd = pmd_offset(pud, page);
  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         goto out;
 107 }
 108
 109 LIST_HEAD(physmem_remappers);
 110
 111 void register_remapper(struct remapper *info)
 112 {
 113         list_add(&info->list, &physmem_remappers);
 114 }
 115
 116 static int check_remapped_addr(unsigned long address, int is_write)
 117 {
 118         struct remapper *remapper;
 119         struct list_head *ele;
 120         __u64 offset;
 121         int fd;
 122
 123         fd = phys_mapping(__pa(address), &offset);
 124         if(fd == -1)
 125                 return(0);
 126
 127         list_for_each(ele, &physmem_remappers){
 128                 remapper = list_entry(ele, struct remapper, list);
 129                 if((*remapper->proc)(fd, address, is_write, offset))
 130                         return(1);
 131         }
 132
 133         return(0);
 134 }
 135
 136 unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 137                    int is_user, void *sc)
 138 {
 139         struct siginfo si;
 140         void *catcher;
 141         int err;
 142
 143         if(!is_user && (address >= start_vm) && (address < end_vm)){
 144                 flush_tlb_kernel_vm();
 145                 return(0);
 146         }
 147         else if(check_remapped_addr(address & PAGE_MASK, is_write))
 148                 return(0);
 149         else if(current->mm == NULL)
 150                 panic("Segfault with no mm");
 151         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
 152
 153         catcher = current->thread.fault_catcher;
 154         if(!err)
 155                 return(0);
 156         else if(catcher != NULL){
 157                 current->thread.fault_addr = (void *) address;
 158                 do_longjmp(catcher, 1);
 159         }
 160         else if(current->thread.fault_addr != NULL)
 161                 panic("fault_addr set but no fault catcher");
 162         else if(arch_fixup(ip, sc))
 163                 return(0);
 164
 165         if(!is_user)
 166                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
 167                       address, ip);
 168
 169         if(err == -EACCES){
 170                 si.si_signo = SIGBUS;
 171                 si.si_errno = 0;
 172                 si.si_code = BUS_ADRERR;
 173                 si.si_addr = (void *)address;
 174                 force_sig_info(SIGBUS, &si, current);
 175         }
 176         else if(err == -ENOMEM){
 177                 printk("VM: killing process %s\n", current->comm);
 178                 do_exit(SIGKILL);
 179         }
 180         else {
 181                 si.si_signo = SIGSEGV;
 182                 si.si_addr = (void *) address;
 183                 current->thread.cr2 = address;
 184                 current->thread.err = is_write;
 185                 force_sig_info(SIGSEGV, &si, current);
 186         }
 187         return(0);
 188 }
 189
 190 void bad_segv(unsigned long address, unsigned long ip, int is_write)
 191 {
 192         struct siginfo si;
 193
 194         si.si_signo = SIGSEGV;
 195         si.si_code = SEGV_ACCERR;
 196         si.si_addr = (void *) address;
 197         current->thread.cr2 = address;
 198         current->thread.err = is_write;
 199         force_sig_info(SIGSEGV, &si, current);
 200 }
 201
 202 void relay_signal(int sig, union uml_pt_regs *regs)
 203 {
 204         if(arch_handle_signal(sig, regs)) return;
 205         if(!UPT_IS_USER(regs))
 206                 panic("Kernel mode signal %d", sig);
 207         force_sig(sig, current);
 208 }
 209
 210 void bus_handler(int sig, union uml_pt_regs *regs)
 211 {
 212         if(current->thread.fault_catcher != NULL)
 213                 do_longjmp(current->thread.fault_catcher, 1);
 214         else relay_signal(sig, regs);
 215 }
 216
 217 void winch(int sig, union uml_pt_regs *regs)
 218 {
 219         do_IRQ(WINCH_IRQ, regs);
 220 }
 221
 222 void trap_init(void)
 223 {
 224 }
 225
 226 DEFINE_SPINLOCK(trap_lock);
 227
 228 static int trap_index = 0;
 229
 230 int next_trap_index(int limit)
 231 {
 232         int ret;
 233
 234         spin_lock(&trap_lock);
 235         ret = trap_index;
 236         if(++trap_index == limit)
 237                 trap_index = 0;
 238         spin_unlock(&trap_lock);
 239         return(ret);
 240 }
 241
 242 /*
 243  * Overrides for Emacs so that we follow Linus's tabbing style.
 244  * Emacs will notice this stuff at the end of the file and automatically
 245  * adjust the settings for this buffer only.  This must remain at the end
 246  * of the file.
 247  * ---------------------------------------------------------------------------
 248  * Local variables:
 249  * c-file-style: "linux"
 250  * End:
 251  */