Chris Zankel | 3f65ce4 | 2005-06-23 22:01:24 -0700 | [diff] [blame] | 1 | // TODO VM_EXEC flag work-around, cache aliasing |
| 2 | /* |
| 3 | * arch/xtensa/mm/fault.c |
| 4 | * |
| 5 | * This file is subject to the terms and conditions of the GNU General Public |
| 6 | * License. See the file "COPYING" in the main directory of this archive |
| 7 | * for more details. |
| 8 | * |
| 9 | * Copyright (C) 2001 - 2005 Tensilica Inc. |
| 10 | * |
| 11 | * Chris Zankel <chris@zankel.net> |
| 12 | * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com> |
| 13 | */ |
| 14 | |
| 15 | #include <linux/mm.h> |
| 16 | #include <linux/module.h> |
| 17 | #include <asm/mmu_context.h> |
| 18 | #include <asm/cacheflush.h> |
| 19 | #include <asm/hardirq.h> |
| 20 | #include <asm/uaccess.h> |
| 21 | #include <asm/system.h> |
| 22 | #include <asm/pgalloc.h> |
| 23 | |
Chris Zankel | 173d668 | 2006-12-10 02:18:48 -0800 | [diff] [blame^] | 24 | unsigned long asid_cache = ASID_USER_FIRST; |
Chris Zankel | 3f65ce4 | 2005-06-23 22:01:24 -0700 | [diff] [blame] | 25 | void bad_page_fault(struct pt_regs*, unsigned long, int); |
| 26 | |
| 27 | /* |
| 28 | * This routine handles page faults. It determines the address, |
| 29 | * and the problem, and then passes it off to one of the appropriate |
| 30 | * routines. |
| 31 | * |
| 32 | * Note: does not handle Miss and MultiHit. |
| 33 | */ |
| 34 | |
| 35 | void do_page_fault(struct pt_regs *regs) |
| 36 | { |
| 37 | struct vm_area_struct * vma; |
| 38 | struct mm_struct *mm = current->mm; |
| 39 | unsigned int exccause = regs->exccause; |
| 40 | unsigned int address = regs->excvaddr; |
| 41 | siginfo_t info; |
| 42 | |
| 43 | int is_write, is_exec; |
| 44 | |
| 45 | info.si_code = SEGV_MAPERR; |
| 46 | |
| 47 | /* We fault-in kernel-space virtual memory on-demand. The |
| 48 | * 'reference' page table is init_mm.pgd. |
| 49 | */ |
| 50 | if (address >= TASK_SIZE && !user_mode(regs)) |
| 51 | goto vmalloc_fault; |
| 52 | |
| 53 | /* If we're in an interrupt or have no user |
| 54 | * context, we must not take the fault.. |
| 55 | */ |
| 56 | if (in_atomic() || !mm) { |
| 57 | bad_page_fault(regs, address, SIGSEGV); |
| 58 | return; |
| 59 | } |
| 60 | |
Chris Zankel | 173d668 | 2006-12-10 02:18:48 -0800 | [diff] [blame^] | 61 | is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0; |
| 62 | is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE || |
| 63 | exccause == EXCCAUSE_ITLB_MISS || |
| 64 | exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0; |
Chris Zankel | 3f65ce4 | 2005-06-23 22:01:24 -0700 | [diff] [blame] | 65 | |
| 66 | #if 0 |
| 67 | printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid, |
| 68 | address, exccause, regs->pc, is_write? "w":"", is_exec? "x":""); |
| 69 | #endif |
| 70 | |
| 71 | down_read(&mm->mmap_sem); |
| 72 | vma = find_vma(mm, address); |
| 73 | |
| 74 | if (!vma) |
| 75 | goto bad_area; |
| 76 | if (vma->vm_start <= address) |
| 77 | goto good_area; |
| 78 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 79 | goto bad_area; |
| 80 | if (expand_stack(vma, address)) |
| 81 | goto bad_area; |
| 82 | |
| 83 | /* Ok, we have a good vm_area for this memory access, so |
| 84 | * we can handle it.. |
| 85 | */ |
| 86 | |
| 87 | good_area: |
| 88 | info.si_code = SEGV_ACCERR; |
| 89 | |
| 90 | if (is_write) { |
| 91 | if (!(vma->vm_flags & VM_WRITE)) |
| 92 | goto bad_area; |
| 93 | } else if (is_exec) { |
| 94 | if (!(vma->vm_flags & VM_EXEC)) |
| 95 | goto bad_area; |
| 96 | } else /* Allow read even from write-only pages. */ |
| 97 | if (!(vma->vm_flags & (VM_READ | VM_WRITE))) |
| 98 | goto bad_area; |
| 99 | |
| 100 | /* If for any reason at all we couldn't handle the fault, |
| 101 | * make sure we exit gracefully rather than endlessly redo |
| 102 | * the fault. |
| 103 | */ |
| 104 | survive: |
| 105 | switch (handle_mm_fault(mm, vma, address, is_write)) { |
| 106 | case VM_FAULT_MINOR: |
| 107 | current->min_flt++; |
| 108 | break; |
| 109 | case VM_FAULT_MAJOR: |
| 110 | current->maj_flt++; |
| 111 | break; |
| 112 | case VM_FAULT_SIGBUS: |
| 113 | goto do_sigbus; |
| 114 | case VM_FAULT_OOM: |
| 115 | goto out_of_memory; |
| 116 | default: |
| 117 | BUG(); |
| 118 | } |
| 119 | |
| 120 | up_read(&mm->mmap_sem); |
| 121 | return; |
| 122 | |
| 123 | /* Something tried to access memory that isn't in our memory map.. |
| 124 | * Fix it, but check if it's kernel or user first.. |
| 125 | */ |
| 126 | bad_area: |
| 127 | up_read(&mm->mmap_sem); |
| 128 | if (user_mode(regs)) { |
| 129 | current->thread.bad_vaddr = address; |
| 130 | current->thread.error_code = is_write; |
| 131 | info.si_signo = SIGSEGV; |
| 132 | info.si_errno = 0; |
| 133 | /* info.si_code has been set above */ |
| 134 | info.si_addr = (void *) address; |
| 135 | force_sig_info(SIGSEGV, &info, current); |
| 136 | return; |
| 137 | } |
| 138 | bad_page_fault(regs, address, SIGSEGV); |
| 139 | return; |
| 140 | |
| 141 | |
| 142 | /* We ran out of memory, or some other thing happened to us that made |
| 143 | * us unable to handle the page fault gracefully. |
| 144 | */ |
| 145 | out_of_memory: |
| 146 | up_read(&mm->mmap_sem); |
Sukadev Bhattiprolu | f400e19 | 2006-09-29 02:00:07 -0700 | [diff] [blame] | 147 | if (is_init(current)) { |
Chris Zankel | 3f65ce4 | 2005-06-23 22:01:24 -0700 | [diff] [blame] | 148 | yield(); |
| 149 | down_read(&mm->mmap_sem); |
| 150 | goto survive; |
| 151 | } |
| 152 | printk("VM: killing process %s\n", current->comm); |
| 153 | if (user_mode(regs)) |
| 154 | do_exit(SIGKILL); |
| 155 | bad_page_fault(regs, address, SIGKILL); |
| 156 | return; |
| 157 | |
| 158 | do_sigbus: |
| 159 | up_read(&mm->mmap_sem); |
| 160 | |
| 161 | /* Send a sigbus, regardless of whether we were in kernel |
| 162 | * or user mode. |
| 163 | */ |
| 164 | current->thread.bad_vaddr = address; |
| 165 | info.si_code = SIGBUS; |
| 166 | info.si_errno = 0; |
| 167 | info.si_code = BUS_ADRERR; |
| 168 | info.si_addr = (void *) address; |
| 169 | force_sig_info(SIGBUS, &info, current); |
| 170 | |
| 171 | /* Kernel mode? Handle exceptions or die */ |
| 172 | if (!user_mode(regs)) |
| 173 | bad_page_fault(regs, address, SIGBUS); |
| 174 | |
| 175 | vmalloc_fault: |
| 176 | { |
| 177 | /* Synchronize this task's top level page-table |
| 178 | * with the 'reference' page table. |
| 179 | */ |
| 180 | struct mm_struct *act_mm = current->active_mm; |
| 181 | int index = pgd_index(address); |
| 182 | pgd_t *pgd, *pgd_k; |
| 183 | pmd_t *pmd, *pmd_k; |
| 184 | pte_t *pte_k; |
| 185 | |
| 186 | if (act_mm == NULL) |
| 187 | goto bad_page_fault; |
| 188 | |
| 189 | pgd = act_mm->pgd + index; |
| 190 | pgd_k = init_mm.pgd + index; |
| 191 | |
| 192 | if (!pgd_present(*pgd_k)) |
| 193 | goto bad_page_fault; |
| 194 | |
| 195 | pgd_val(*pgd) = pgd_val(*pgd_k); |
| 196 | |
| 197 | pmd = pmd_offset(pgd, address); |
| 198 | pmd_k = pmd_offset(pgd_k, address); |
| 199 | if (!pmd_present(*pmd) || !pmd_present(*pmd_k)) |
| 200 | goto bad_page_fault; |
| 201 | |
| 202 | pmd_val(*pmd) = pmd_val(*pmd_k); |
| 203 | pte_k = pte_offset_kernel(pmd_k, address); |
| 204 | |
| 205 | if (!pte_present(*pte_k)) |
| 206 | goto bad_page_fault; |
| 207 | return; |
| 208 | } |
| 209 | bad_page_fault: |
| 210 | bad_page_fault(regs, address, SIGKILL); |
| 211 | return; |
| 212 | } |
| 213 | |
| 214 | |
| 215 | void |
| 216 | bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) |
| 217 | { |
| 218 | extern void die(const char*, struct pt_regs*, long); |
| 219 | const struct exception_table_entry *entry; |
| 220 | |
| 221 | /* Are we prepared to handle this kernel fault? */ |
| 222 | if ((entry = search_exception_tables(regs->pc)) != NULL) { |
| 223 | #if 1 |
| 224 | printk(KERN_DEBUG "%s: Exception at pc=%#010lx (%lx)\n", |
| 225 | current->comm, regs->pc, entry->fixup); |
| 226 | #endif |
| 227 | current->thread.bad_uaddr = address; |
| 228 | regs->pc = entry->fixup; |
| 229 | return; |
| 230 | } |
| 231 | |
| 232 | /* Oops. The kernel tried to access some bad page. We'll have to |
| 233 | * terminate things with extreme prejudice. |
| 234 | */ |
| 235 | printk(KERN_ALERT "Unable to handle kernel paging request at virtual " |
| 236 | "address %08lx\n pc = %08lx, ra = %08lx\n", |
| 237 | address, regs->pc, regs->areg[0]); |
| 238 | die("Oops", regs, sig); |
| 239 | do_exit(sig); |
| 240 | } |
| 241 | |