1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * fault.c: Page fault handlers for the Sparc. 4 * 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be) 7 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 8 */ 9 10 #include <asm/head.h> 11 12 #include <linux/string.h> 13 #include <linux/types.h> 14 #include <linux/sched.h> 15 #include <linux/ptrace.h> 16 #include <linux/mman.h> 17 #include <linux/threads.h> 18 #include <linux/kernel.h> 19 #include <linux/signal.h> 20 #include <linux/mm.h> 21 #include <linux/smp.h> 22 #include <linux/perf_event.h> 23 #include <linux/interrupt.h> 24 #include <linux/kdebug.h> 25 #include <linux/uaccess.h> 26 #include <linux/extable.h> 27 28 #include <asm/page.h> 29 #include <asm/openprom.h> 30 #include <asm/oplib.h> 31 #include <asm/setup.h> 32 #include <asm/smp.h> 33 #include <asm/traps.h> 34 35 #include "mm_32.h" 36 37 int show_unhandled_signals = 1; 38 39 static void __noreturn unhandled_fault(unsigned long address, 40 struct task_struct *tsk, 41 struct pt_regs *regs) 42 { 43 if ((unsigned long) address < PAGE_SIZE) { 44 printk(KERN_ALERT 45 "Unable to handle kernel NULL pointer dereference\n"); 46 } else { 47 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n", 48 address); 49 } 50 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n", 51 (tsk->mm ? tsk->mm->context : tsk->active_mm->context)); 52 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n", 53 (tsk->mm ? (unsigned long) tsk->mm->pgd : 54 (unsigned long) tsk->active_mm->pgd)); 55 die_if_kernel("Oops", regs); 56 } 57 58 static inline void 59 show_signal_msg(struct pt_regs *regs, int sig, int code, 60 unsigned long address, struct task_struct *tsk) 61 { 62 if (!unhandled_signal(tsk, sig)) 63 return; 64 65 if (!printk_ratelimit()) 66 return; 67 68 printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x", 69 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 70 tsk->comm, task_pid_nr(tsk), address, 71 (void *)regs->pc, (void *)regs->u_regs[UREG_I7], 72 (void *)regs->u_regs[UREG_FP], code); 73 74 print_vma_addr(KERN_CONT " in ", regs->pc); 75 76 printk(KERN_CONT "\n"); 77 } 78 79 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs, 80 unsigned long addr) 81 { 82 if (unlikely(show_unhandled_signals)) 83 show_signal_msg(regs, sig, code, 84 addr, current); 85 86 force_sig_fault(sig, code, (void __user *) addr); 87 } 88 89 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault) 90 { 91 unsigned int insn; 92 93 if (text_fault) 94 return regs->pc; 95 96 if (regs->psr & PSR_PS) 97 insn = *(unsigned int *) regs->pc; 98 else 99 __get_user(insn, (unsigned int *) regs->pc); 100 101 return safe_compute_effective_address(regs, insn); 102 } 103 104 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 105 int text_fault) 106 { 107 unsigned long addr = compute_si_addr(regs, text_fault); 108 109 __do_fault_siginfo(code, sig, regs, addr); 110 } 111 112 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write, 113 unsigned long address) 114 { 115 struct vm_area_struct *vma; 116 struct task_struct *tsk = current; 117 struct mm_struct *mm = tsk->mm; 118 int from_user = !(regs->psr & PSR_PS); 119 int code; 120 vm_fault_t fault; 121 unsigned int flags = FAULT_FLAG_DEFAULT; 122 123 if (text_fault) 124 address = regs->pc; 125 126 /* 127 * We fault-in kernel-space virtual memory on-demand. The 128 * 'reference' page table is init_mm.pgd. 129 * 130 * NOTE! We MUST NOT take any locks for this case. We may 131 * be in an interrupt or a critical region, and should 132 * only copy the information from the master page table, 133 * nothing more. 134 */ 135 code = SEGV_MAPERR; 136 if (address >= TASK_SIZE) 137 goto vmalloc_fault; 138 139 /* 140 * If we're in an interrupt or have no user 141 * context, we must not take the fault.. 142 */ 143 if (pagefault_disabled() || !mm) 144 goto no_context; 145 146 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 147 148 retry: 149 mmap_read_lock(mm); 150 151 if (!from_user && address >= PAGE_OFFSET) 152 goto bad_area; 153 154 vma = find_vma(mm, address); 155 if (!vma) 156 goto bad_area; 157 if (vma->vm_start <= address) 158 goto good_area; 159 if (!(vma->vm_flags & VM_GROWSDOWN)) 160 goto bad_area; 161 if (expand_stack(vma, address)) 162 goto bad_area; 163 /* 164 * Ok, we have a good vm_area for this memory access, so 165 * we can handle it.. 166 */ 167 good_area: 168 code = SEGV_ACCERR; 169 if (write) { 170 if (!(vma->vm_flags & VM_WRITE)) 171 goto bad_area; 172 } else { 173 /* Allow reads even for write-only mappings */ 174 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 175 goto bad_area; 176 } 177 178 if (from_user) 179 flags |= FAULT_FLAG_USER; 180 if (write) 181 flags |= FAULT_FLAG_WRITE; 182 183 /* 184 * If for any reason at all we couldn't handle the fault, 185 * make sure we exit gracefully rather than endlessly redo 186 * the fault. 187 */ 188 fault = handle_mm_fault(vma, address, flags, regs); 189 190 if (fault_signal_pending(fault, regs)) 191 return; 192 193 /* The fault is fully completed (including releasing mmap lock) */ 194 if (fault & VM_FAULT_COMPLETED) 195 return; 196 197 if (unlikely(fault & VM_FAULT_ERROR)) { 198 if (fault & VM_FAULT_OOM) 199 goto out_of_memory; 200 else if (fault & VM_FAULT_SIGSEGV) 201 goto bad_area; 202 else if (fault & VM_FAULT_SIGBUS) 203 goto do_sigbus; 204 BUG(); 205 } 206 207 if (fault & VM_FAULT_RETRY) { 208 flags |= FAULT_FLAG_TRIED; 209 210 /* No need to mmap_read_unlock(mm) as we would 211 * have already released it in __lock_page_or_retry 212 * in mm/filemap.c. 213 */ 214 215 goto retry; 216 } 217 218 mmap_read_unlock(mm); 219 return; 220 221 /* 222 * Something tried to access memory that isn't in our memory map.. 223 * Fix it, but check if it's kernel or user first.. 224 */ 225 bad_area: 226 mmap_read_unlock(mm); 227 228 bad_area_nosemaphore: 229 /* User mode accesses just cause a SIGSEGV */ 230 if (from_user) { 231 do_fault_siginfo(code, SIGSEGV, regs, text_fault); 232 return; 233 } 234 235 /* Is this in ex_table? */ 236 no_context: 237 if (!from_user) { 238 const struct exception_table_entry *entry; 239 240 entry = search_exception_tables(regs->pc); 241 #ifdef DEBUG_EXCEPTIONS 242 printk("Exception: PC<%08lx> faddr<%08lx>\n", 243 regs->pc, address); 244 printk("EX_TABLE: insn<%08lx> fixup<%08x>\n", 245 regs->pc, entry->fixup); 246 #endif 247 regs->pc = entry->fixup; 248 regs->npc = regs->pc + 4; 249 return; 250 } 251 252 unhandled_fault(address, tsk, regs); 253 254 /* 255 * We ran out of memory, or some other thing happened to us that made 256 * us unable to handle the page fault gracefully. 257 */ 258 out_of_memory: 259 mmap_read_unlock(mm); 260 if (from_user) { 261 pagefault_out_of_memory(); 262 return; 263 } 264 goto no_context; 265 266 do_sigbus: 267 mmap_read_unlock(mm); 268 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault); 269 if (!from_user) 270 goto no_context; 271 272 vmalloc_fault: 273 { 274 /* 275 * Synchronize this task's top level page-table 276 * with the 'reference' page table. 277 */ 278 int offset = pgd_index(address); 279 pgd_t *pgd, *pgd_k; 280 p4d_t *p4d, *p4d_k; 281 pud_t *pud, *pud_k; 282 pmd_t *pmd, *pmd_k; 283 284 pgd = tsk->active_mm->pgd + offset; 285 pgd_k = init_mm.pgd + offset; 286 287 if (!pgd_present(*pgd)) { 288 if (!pgd_present(*pgd_k)) 289 goto bad_area_nosemaphore; 290 pgd_val(*pgd) = pgd_val(*pgd_k); 291 return; 292 } 293 294 p4d = p4d_offset(pgd, address); 295 pud = pud_offset(p4d, address); 296 pmd = pmd_offset(pud, address); 297 298 p4d_k = p4d_offset(pgd_k, address); 299 pud_k = pud_offset(p4d_k, address); 300 pmd_k = pmd_offset(pud_k, address); 301 302 if (pmd_present(*pmd) || !pmd_present(*pmd_k)) 303 goto bad_area_nosemaphore; 304 305 *pmd = *pmd_k; 306 return; 307 } 308 } 309 310 /* This always deals with user addresses. */ 311 static void force_user_fault(unsigned long address, int write) 312 { 313 struct vm_area_struct *vma; 314 struct task_struct *tsk = current; 315 struct mm_struct *mm = tsk->mm; 316 unsigned int flags = FAULT_FLAG_USER; 317 int code; 318 319 code = SEGV_MAPERR; 320 321 mmap_read_lock(mm); 322 vma = find_vma(mm, address); 323 if (!vma) 324 goto bad_area; 325 if (vma->vm_start <= address) 326 goto good_area; 327 if (!(vma->vm_flags & VM_GROWSDOWN)) 328 goto bad_area; 329 if (expand_stack(vma, address)) 330 goto bad_area; 331 good_area: 332 code = SEGV_ACCERR; 333 if (write) { 334 if (!(vma->vm_flags & VM_WRITE)) 335 goto bad_area; 336 flags |= FAULT_FLAG_WRITE; 337 } else { 338 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 339 goto bad_area; 340 } 341 switch (handle_mm_fault(vma, address, flags, NULL)) { 342 case VM_FAULT_SIGBUS: 343 case VM_FAULT_OOM: 344 goto do_sigbus; 345 } 346 mmap_read_unlock(mm); 347 return; 348 bad_area: 349 mmap_read_unlock(mm); 350 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address); 351 return; 352 353 do_sigbus: 354 mmap_read_unlock(mm); 355 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address); 356 } 357 358 static void check_stack_aligned(unsigned long sp) 359 { 360 if (sp & 0x7UL) 361 force_sig(SIGILL); 362 } 363 364 void window_overflow_fault(void) 365 { 366 unsigned long sp; 367 368 sp = current_thread_info()->rwbuf_stkptrs[0]; 369 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 370 force_user_fault(sp + 0x38, 1); 371 force_user_fault(sp, 1); 372 373 check_stack_aligned(sp); 374 } 375 376 void window_underflow_fault(unsigned long sp) 377 { 378 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 379 force_user_fault(sp + 0x38, 0); 380 force_user_fault(sp, 0); 381 382 check_stack_aligned(sp); 383 } 384 385 void window_ret_fault(struct pt_regs *regs) 386 { 387 unsigned long sp; 388 389 sp = regs->u_regs[UREG_FP]; 390 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 391 force_user_fault(sp + 0x38, 0); 392 force_user_fault(sp, 0); 393 394 check_stack_aligned(sp); 395 } 396