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 if (!from_user && address >= PAGE_OFFSET) 147 goto no_context; 148 149 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 150 151 retry: 152 vma = lock_mm_and_find_vma(mm, address, regs); 153 if (!vma) 154 goto bad_area_nosemaphore; 155 /* 156 * Ok, we have a good vm_area for this memory access, so 157 * we can handle it.. 158 */ 159 code = SEGV_ACCERR; 160 if (write) { 161 if (!(vma->vm_flags & VM_WRITE)) 162 goto bad_area; 163 } else { 164 /* Allow reads even for write-only mappings */ 165 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 166 goto bad_area; 167 } 168 169 if (from_user) 170 flags |= FAULT_FLAG_USER; 171 if (write) 172 flags |= FAULT_FLAG_WRITE; 173 174 /* 175 * If for any reason at all we couldn't handle the fault, 176 * make sure we exit gracefully rather than endlessly redo 177 * the fault. 178 */ 179 fault = handle_mm_fault(vma, address, flags, regs); 180 181 if (fault_signal_pending(fault, regs)) { 182 if (!from_user) 183 goto no_context; 184 return; 185 } 186 187 /* The fault is fully completed (including releasing mmap lock) */ 188 if (fault & VM_FAULT_COMPLETED) 189 return; 190 191 if (unlikely(fault & VM_FAULT_ERROR)) { 192 if (fault & VM_FAULT_OOM) 193 goto out_of_memory; 194 else if (fault & VM_FAULT_SIGSEGV) 195 goto bad_area; 196 else if (fault & VM_FAULT_SIGBUS) 197 goto do_sigbus; 198 BUG(); 199 } 200 201 if (fault & VM_FAULT_RETRY) { 202 flags |= FAULT_FLAG_TRIED; 203 204 /* No need to mmap_read_unlock(mm) as we would 205 * have already released it in __lock_page_or_retry 206 * in mm/filemap.c. 207 */ 208 209 goto retry; 210 } 211 212 mmap_read_unlock(mm); 213 return; 214 215 /* 216 * Something tried to access memory that isn't in our memory map.. 217 * Fix it, but check if it's kernel or user first.. 218 */ 219 bad_area: 220 mmap_read_unlock(mm); 221 222 bad_area_nosemaphore: 223 /* User mode accesses just cause a SIGSEGV */ 224 if (from_user) { 225 do_fault_siginfo(code, SIGSEGV, regs, text_fault); 226 return; 227 } 228 229 /* Is this in ex_table? */ 230 no_context: 231 if (!from_user) { 232 const struct exception_table_entry *entry; 233 234 entry = search_exception_tables(regs->pc); 235 #ifdef DEBUG_EXCEPTIONS 236 printk("Exception: PC<%08lx> faddr<%08lx>\n", 237 regs->pc, address); 238 printk("EX_TABLE: insn<%08lx> fixup<%08x>\n", 239 regs->pc, entry->fixup); 240 #endif 241 regs->pc = entry->fixup; 242 regs->npc = regs->pc + 4; 243 return; 244 } 245 246 unhandled_fault(address, tsk, regs); 247 248 /* 249 * We ran out of memory, or some other thing happened to us that made 250 * us unable to handle the page fault gracefully. 251 */ 252 out_of_memory: 253 mmap_read_unlock(mm); 254 if (from_user) { 255 pagefault_out_of_memory(); 256 return; 257 } 258 goto no_context; 259 260 do_sigbus: 261 mmap_read_unlock(mm); 262 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault); 263 if (!from_user) 264 goto no_context; 265 266 vmalloc_fault: 267 { 268 /* 269 * Synchronize this task's top level page-table 270 * with the 'reference' page table. 271 */ 272 int offset = pgd_index(address); 273 pgd_t *pgd, *pgd_k; 274 p4d_t *p4d, *p4d_k; 275 pud_t *pud, *pud_k; 276 pmd_t *pmd, *pmd_k; 277 278 pgd = tsk->active_mm->pgd + offset; 279 pgd_k = init_mm.pgd + offset; 280 281 if (!pgd_present(*pgd)) { 282 if (!pgd_present(*pgd_k)) 283 goto bad_area_nosemaphore; 284 pgd_val(*pgd) = pgd_val(*pgd_k); 285 return; 286 } 287 288 p4d = p4d_offset(pgd, address); 289 pud = pud_offset(p4d, address); 290 pmd = pmd_offset(pud, address); 291 292 p4d_k = p4d_offset(pgd_k, address); 293 pud_k = pud_offset(p4d_k, address); 294 pmd_k = pmd_offset(pud_k, address); 295 296 if (pmd_present(*pmd) || !pmd_present(*pmd_k)) 297 goto bad_area_nosemaphore; 298 299 *pmd = *pmd_k; 300 return; 301 } 302 } 303 304 /* This always deals with user addresses. */ 305 static void force_user_fault(unsigned long address, int write) 306 { 307 struct vm_area_struct *vma; 308 struct task_struct *tsk = current; 309 struct mm_struct *mm = tsk->mm; 310 unsigned int flags = FAULT_FLAG_USER; 311 int code; 312 313 code = SEGV_MAPERR; 314 315 vma = lock_mm_and_find_vma(mm, address, NULL); 316 if (!vma) 317 goto bad_area_nosemaphore; 318 code = SEGV_ACCERR; 319 if (write) { 320 if (!(vma->vm_flags & VM_WRITE)) 321 goto bad_area; 322 flags |= FAULT_FLAG_WRITE; 323 } else { 324 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 325 goto bad_area; 326 } 327 switch (handle_mm_fault(vma, address, flags, NULL)) { 328 case VM_FAULT_SIGBUS: 329 case VM_FAULT_OOM: 330 goto do_sigbus; 331 } 332 mmap_read_unlock(mm); 333 return; 334 bad_area: 335 mmap_read_unlock(mm); 336 bad_area_nosemaphore: 337 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address); 338 return; 339 340 do_sigbus: 341 mmap_read_unlock(mm); 342 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address); 343 } 344 345 static void check_stack_aligned(unsigned long sp) 346 { 347 if (sp & 0x7UL) 348 force_sig(SIGILL); 349 } 350 351 void window_overflow_fault(void) 352 { 353 unsigned long sp; 354 355 sp = current_thread_info()->rwbuf_stkptrs[0]; 356 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 357 force_user_fault(sp + 0x38, 1); 358 force_user_fault(sp, 1); 359 360 check_stack_aligned(sp); 361 } 362 363 void window_underflow_fault(unsigned long sp) 364 { 365 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 366 force_user_fault(sp + 0x38, 0); 367 force_user_fault(sp, 0); 368 369 check_stack_aligned(sp); 370 } 371 372 void window_ret_fault(struct pt_regs *regs) 373 { 374 unsigned long sp; 375 376 sp = regs->u_regs[UREG_FP]; 377 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 378 force_user_fault(sp + 0x38, 0); 379 force_user_fault(sp, 0); 380 381 check_stack_aligned(sp); 382 } 383