James Hogan | f5df8e2 | 2012-10-09 10:54:17 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Meta page fault handling. |
| 3 | * |
| 4 | * Copyright (C) 2005-2012 Imagination Technologies Ltd. |
| 5 | */ |
| 6 | |
| 7 | #include <linux/mman.h> |
| 8 | #include <linux/mm.h> |
| 9 | #include <linux/kernel.h> |
| 10 | #include <linux/ptrace.h> |
| 11 | #include <linux/interrupt.h> |
| 12 | #include <linux/uaccess.h> |
| 13 | |
| 14 | #include <asm/tlbflush.h> |
| 15 | #include <asm/mmu.h> |
| 16 | #include <asm/traps.h> |
| 17 | |
| 18 | /* Clear any pending catch buffer state. */ |
| 19 | static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr, |
| 20 | unsigned int trapno) |
| 21 | { |
| 22 | PTBICTXEXTCB0 cbuf = regs->extcb0; |
| 23 | |
| 24 | switch (trapno) { |
| 25 | /* Instruction fetch faults leave no catch buffer state. */ |
| 26 | case TBIXXF_SIGNUM_IGF: |
| 27 | case TBIXXF_SIGNUM_IPF: |
| 28 | return; |
| 29 | default: |
| 30 | if (cbuf[0].CBAddr == addr) { |
| 31 | cbuf[0].CBAddr = 0; |
| 32 | cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS; |
| 33 | |
| 34 | /* And, as this is the ONLY catch entry, we |
| 35 | * need to clear the cbuf bit from the context! |
| 36 | */ |
| 37 | regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT | |
| 38 | TBICTX_XCBF_BIT); |
| 39 | |
| 40 | return; |
| 41 | } |
| 42 | pr_err("Failed to clear cbuf entry!\n"); |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | int show_unhandled_signals = 1; |
| 47 | |
| 48 | int do_page_fault(struct pt_regs *regs, unsigned long address, |
| 49 | unsigned int write_access, unsigned int trapno) |
| 50 | { |
| 51 | struct task_struct *tsk; |
| 52 | struct mm_struct *mm; |
| 53 | struct vm_area_struct *vma, *prev_vma; |
| 54 | siginfo_t info; |
| 55 | int fault; |
Johannes Weiner | 759496b | 2013-09-12 15:13:39 -0700 | [diff] [blame] | 56 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
James Hogan | f5df8e2 | 2012-10-09 10:54:17 +0100 | [diff] [blame] | 57 | |
| 58 | tsk = current; |
| 59 | |
| 60 | if ((address >= VMALLOC_START) && (address < VMALLOC_END)) { |
| 61 | /* |
| 62 | * Synchronize this task's top level page-table |
| 63 | * with the 'reference' page table. |
| 64 | * |
| 65 | * Do _not_ use "tsk" here. We might be inside |
| 66 | * an interrupt in the middle of a task switch.. |
| 67 | */ |
| 68 | int offset = pgd_index(address); |
| 69 | pgd_t *pgd, *pgd_k; |
| 70 | pud_t *pud, *pud_k; |
| 71 | pmd_t *pmd, *pmd_k; |
| 72 | pte_t *pte_k; |
| 73 | |
| 74 | pgd = ((pgd_t *)mmu_get_base()) + offset; |
| 75 | pgd_k = swapper_pg_dir + offset; |
| 76 | |
| 77 | /* This will never happen with the folded page table. */ |
| 78 | if (!pgd_present(*pgd)) { |
| 79 | if (!pgd_present(*pgd_k)) |
| 80 | goto bad_area_nosemaphore; |
| 81 | set_pgd(pgd, *pgd_k); |
| 82 | return 0; |
| 83 | } |
| 84 | |
| 85 | pud = pud_offset(pgd, address); |
| 86 | pud_k = pud_offset(pgd_k, address); |
| 87 | if (!pud_present(*pud_k)) |
| 88 | goto bad_area_nosemaphore; |
| 89 | set_pud(pud, *pud_k); |
| 90 | |
| 91 | pmd = pmd_offset(pud, address); |
| 92 | pmd_k = pmd_offset(pud_k, address); |
| 93 | if (!pmd_present(*pmd_k)) |
| 94 | goto bad_area_nosemaphore; |
| 95 | set_pmd(pmd, *pmd_k); |
| 96 | |
| 97 | pte_k = pte_offset_kernel(pmd_k, address); |
| 98 | if (!pte_present(*pte_k)) |
| 99 | goto bad_area_nosemaphore; |
| 100 | |
| 101 | /* May only be needed on Chorus2 */ |
| 102 | flush_tlb_all(); |
| 103 | return 0; |
| 104 | } |
| 105 | |
| 106 | mm = tsk->mm; |
| 107 | |
| 108 | if (in_atomic() || !mm) |
| 109 | goto no_context; |
| 110 | |
Johannes Weiner | 759496b | 2013-09-12 15:13:39 -0700 | [diff] [blame] | 111 | if (user_mode(regs)) |
| 112 | flags |= FAULT_FLAG_USER; |
James Hogan | f5df8e2 | 2012-10-09 10:54:17 +0100 | [diff] [blame] | 113 | retry: |
| 114 | down_read(&mm->mmap_sem); |
| 115 | |
| 116 | vma = find_vma_prev(mm, address, &prev_vma); |
| 117 | |
| 118 | if (!vma || address < vma->vm_start) |
| 119 | goto check_expansion; |
| 120 | |
| 121 | good_area: |
| 122 | if (write_access) { |
| 123 | if (!(vma->vm_flags & VM_WRITE)) |
| 124 | goto bad_area; |
Johannes Weiner | 759496b | 2013-09-12 15:13:39 -0700 | [diff] [blame] | 125 | flags |= FAULT_FLAG_WRITE; |
James Hogan | f5df8e2 | 2012-10-09 10:54:17 +0100 | [diff] [blame] | 126 | } else { |
| 127 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
| 128 | goto bad_area; |
| 129 | } |
| 130 | |
| 131 | /* |
| 132 | * If for any reason at all we couldn't handle the fault, |
| 133 | * make sure we exit gracefully rather than endlessly redo |
| 134 | * the fault. |
| 135 | */ |
| 136 | fault = handle_mm_fault(mm, vma, address, flags); |
| 137 | |
| 138 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) |
| 139 | return 0; |
| 140 | |
| 141 | if (unlikely(fault & VM_FAULT_ERROR)) { |
| 142 | if (fault & VM_FAULT_OOM) |
| 143 | goto out_of_memory; |
Linus Torvalds | 33692f2 | 2015-01-29 10:51:32 -0800 | [diff] [blame^] | 144 | else if (fault & VM_FAULT_SIGSEGV) |
| 145 | goto bad_area; |
James Hogan | f5df8e2 | 2012-10-09 10:54:17 +0100 | [diff] [blame] | 146 | else if (fault & VM_FAULT_SIGBUS) |
| 147 | goto do_sigbus; |
| 148 | BUG(); |
| 149 | } |
| 150 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
| 151 | if (fault & VM_FAULT_MAJOR) |
| 152 | tsk->maj_flt++; |
| 153 | else |
| 154 | tsk->min_flt++; |
| 155 | if (fault & VM_FAULT_RETRY) { |
| 156 | flags &= ~FAULT_FLAG_ALLOW_RETRY; |
| 157 | flags |= FAULT_FLAG_TRIED; |
| 158 | |
| 159 | /* |
| 160 | * No need to up_read(&mm->mmap_sem) as we would |
| 161 | * have already released it in __lock_page_or_retry |
| 162 | * in mm/filemap.c. |
| 163 | */ |
| 164 | |
| 165 | goto retry; |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | up_read(&mm->mmap_sem); |
| 170 | return 0; |
| 171 | |
| 172 | check_expansion: |
| 173 | vma = prev_vma; |
| 174 | if (vma && (expand_stack(vma, address) == 0)) |
| 175 | goto good_area; |
| 176 | |
| 177 | bad_area: |
| 178 | up_read(&mm->mmap_sem); |
| 179 | |
| 180 | bad_area_nosemaphore: |
| 181 | if (user_mode(regs)) { |
| 182 | info.si_signo = SIGSEGV; |
| 183 | info.si_errno = 0; |
| 184 | info.si_code = SEGV_MAPERR; |
| 185 | info.si_addr = (__force void __user *)address; |
| 186 | info.si_trapno = trapno; |
| 187 | |
| 188 | if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && |
| 189 | printk_ratelimit()) { |
| 190 | pr_info("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)", |
| 191 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, |
| 192 | tsk->comm, task_pid_nr(tsk), address, |
| 193 | regs->ctx.CurrPC, regs->ctx.AX[0].U0, |
| 194 | write_access, trapno, trap_name(trapno)); |
| 195 | print_vma_addr(" in ", regs->ctx.CurrPC); |
| 196 | print_vma_addr(" rtp in ", regs->ctx.DX[4].U1); |
| 197 | printk("\n"); |
| 198 | show_regs(regs); |
| 199 | } |
| 200 | force_sig_info(SIGSEGV, &info, tsk); |
| 201 | return 1; |
| 202 | } |
| 203 | goto no_context; |
| 204 | |
| 205 | do_sigbus: |
| 206 | up_read(&mm->mmap_sem); |
| 207 | |
| 208 | /* |
| 209 | * Send a sigbus, regardless of whether we were in kernel |
| 210 | * or user mode. |
| 211 | */ |
| 212 | info.si_signo = SIGBUS; |
| 213 | info.si_errno = 0; |
| 214 | info.si_code = BUS_ADRERR; |
| 215 | info.si_addr = (__force void __user *)address; |
| 216 | info.si_trapno = trapno; |
| 217 | force_sig_info(SIGBUS, &info, tsk); |
| 218 | |
| 219 | /* Kernel mode? Handle exceptions or die */ |
| 220 | if (!user_mode(regs)) |
| 221 | goto no_context; |
| 222 | |
| 223 | return 1; |
| 224 | |
| 225 | /* |
| 226 | * We ran out of memory, or some other thing happened to us that made |
| 227 | * us unable to handle the page fault gracefully. |
| 228 | */ |
| 229 | out_of_memory: |
| 230 | up_read(&mm->mmap_sem); |
Johannes Weiner | 609838c | 2013-07-08 15:59:50 -0700 | [diff] [blame] | 231 | if (user_mode(regs)) { |
| 232 | pagefault_out_of_memory(); |
| 233 | return 1; |
| 234 | } |
James Hogan | f5df8e2 | 2012-10-09 10:54:17 +0100 | [diff] [blame] | 235 | |
| 236 | no_context: |
| 237 | /* Are we prepared to handle this kernel fault? */ |
| 238 | if (fixup_exception(regs)) { |
| 239 | clear_cbuf_entry(regs, address, trapno); |
| 240 | return 1; |
| 241 | } |
| 242 | |
| 243 | die("Oops", regs, (write_access << 15) | trapno, address); |
| 244 | do_exit(SIGKILL); |
| 245 | } |