1 /* 2 * Common signal handling code for both 32 and 64 bits 3 * 4 * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation 5 * Extracted from signal_32.c and signal_64.c 6 * 7 * This file is subject to the terms and conditions of the GNU General 8 * Public License. See the file README.legal in the main directory of 9 * this archive for more details. 10 */ 11 12 #include <linux/tracehook.h> 13 #include <linux/signal.h> 14 #include <linux/uprobes.h> 15 #include <linux/key.h> 16 #include <linux/context_tracking.h> 17 #include <linux/livepatch.h> 18 #include <linux/syscalls.h> 19 #include <asm/hw_breakpoint.h> 20 #include <linux/uaccess.h> 21 #include <asm/switch_to.h> 22 #include <asm/unistd.h> 23 #include <asm/debug.h> 24 #include <asm/tm.h> 25 26 #include "signal.h" 27 28 #ifdef CONFIG_VSX 29 unsigned long copy_fpr_to_user(void __user *to, 30 struct task_struct *task) 31 { 32 u64 buf[ELF_NFPREG]; 33 int i; 34 35 /* save FPR copy to local buffer then write to the thread_struct */ 36 for (i = 0; i < (ELF_NFPREG - 1) ; i++) 37 buf[i] = task->thread.TS_FPR(i); 38 buf[i] = task->thread.fp_state.fpscr; 39 return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double)); 40 } 41 42 unsigned long copy_fpr_from_user(struct task_struct *task, 43 void __user *from) 44 { 45 u64 buf[ELF_NFPREG]; 46 int i; 47 48 if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double))) 49 return 1; 50 for (i = 0; i < (ELF_NFPREG - 1) ; i++) 51 task->thread.TS_FPR(i) = buf[i]; 52 task->thread.fp_state.fpscr = buf[i]; 53 54 return 0; 55 } 56 57 unsigned long copy_vsx_to_user(void __user *to, 58 struct task_struct *task) 59 { 60 u64 buf[ELF_NVSRHALFREG]; 61 int i; 62 63 /* save FPR copy to local buffer then write to the thread_struct */ 64 for (i = 0; i < ELF_NVSRHALFREG; i++) 65 buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET]; 66 return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double)); 67 } 68 69 unsigned long copy_vsx_from_user(struct task_struct *task, 70 void __user *from) 71 { 72 u64 buf[ELF_NVSRHALFREG]; 73 int i; 74 75 if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double))) 76 return 1; 77 for (i = 0; i < ELF_NVSRHALFREG ; i++) 78 task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i]; 79 return 0; 80 } 81 82 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 83 unsigned long copy_ckfpr_to_user(void __user *to, 84 struct task_struct *task) 85 { 86 u64 buf[ELF_NFPREG]; 87 int i; 88 89 /* save FPR copy to local buffer then write to the thread_struct */ 90 for (i = 0; i < (ELF_NFPREG - 1) ; i++) 91 buf[i] = task->thread.TS_CKFPR(i); 92 buf[i] = task->thread.ckfp_state.fpscr; 93 return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double)); 94 } 95 96 unsigned long copy_ckfpr_from_user(struct task_struct *task, 97 void __user *from) 98 { 99 u64 buf[ELF_NFPREG]; 100 int i; 101 102 if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double))) 103 return 1; 104 for (i = 0; i < (ELF_NFPREG - 1) ; i++) 105 task->thread.TS_CKFPR(i) = buf[i]; 106 task->thread.ckfp_state.fpscr = buf[i]; 107 108 return 0; 109 } 110 111 unsigned long copy_ckvsx_to_user(void __user *to, 112 struct task_struct *task) 113 { 114 u64 buf[ELF_NVSRHALFREG]; 115 int i; 116 117 /* save FPR copy to local buffer then write to the thread_struct */ 118 for (i = 0; i < ELF_NVSRHALFREG; i++) 119 buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET]; 120 return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double)); 121 } 122 123 unsigned long copy_ckvsx_from_user(struct task_struct *task, 124 void __user *from) 125 { 126 u64 buf[ELF_NVSRHALFREG]; 127 int i; 128 129 if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double))) 130 return 1; 131 for (i = 0; i < ELF_NVSRHALFREG ; i++) 132 task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i]; 133 return 0; 134 } 135 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ 136 #else 137 inline unsigned long copy_fpr_to_user(void __user *to, 138 struct task_struct *task) 139 { 140 return __copy_to_user(to, task->thread.fp_state.fpr, 141 ELF_NFPREG * sizeof(double)); 142 } 143 144 inline unsigned long copy_fpr_from_user(struct task_struct *task, 145 void __user *from) 146 { 147 return __copy_from_user(task->thread.fp_state.fpr, from, 148 ELF_NFPREG * sizeof(double)); 149 } 150 151 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 152 inline unsigned long copy_ckfpr_to_user(void __user *to, 153 struct task_struct *task) 154 { 155 return __copy_to_user(to, task->thread.ckfp_state.fpr, 156 ELF_NFPREG * sizeof(double)); 157 } 158 159 inline unsigned long copy_ckfpr_from_user(struct task_struct *task, 160 void __user *from) 161 { 162 return __copy_from_user(task->thread.ckfp_state.fpr, from, 163 ELF_NFPREG * sizeof(double)); 164 } 165 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ 166 #endif 167 168 /* Log an error when sending an unhandled signal to a process. Controlled 169 * through debug.exception-trace sysctl. 170 */ 171 172 int show_unhandled_signals = 1; 173 174 /* 175 * Allocate space for the signal frame 176 */ 177 void __user *get_sigframe(struct ksignal *ksig, unsigned long sp, 178 size_t frame_size, int is_32) 179 { 180 unsigned long oldsp, newsp; 181 182 /* Default to using normal stack */ 183 oldsp = get_clean_sp(sp, is_32); 184 oldsp = sigsp(oldsp, ksig); 185 newsp = (oldsp - frame_size) & ~0xFUL; 186 187 /* Check access */ 188 if (!access_ok((void __user *)newsp, oldsp - newsp)) 189 return NULL; 190 191 return (void __user *)newsp; 192 } 193 194 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 195 int has_handler) 196 { 197 unsigned long ret = regs->gpr[3]; 198 int restart = 1; 199 200 /* syscall ? */ 201 if (!trap_is_syscall(regs)) 202 return; 203 204 if (trap_norestart(regs)) 205 return; 206 207 /* error signalled ? */ 208 if (trap_is_scv(regs)) { 209 /* 32-bit compat mode sign extend? */ 210 if (!IS_ERR_VALUE(ret)) 211 return; 212 ret = -ret; 213 } else if (!(regs->ccr & 0x10000000)) { 214 return; 215 } 216 217 switch (ret) { 218 case ERESTART_RESTARTBLOCK: 219 case ERESTARTNOHAND: 220 /* ERESTARTNOHAND means that the syscall should only be 221 * restarted if there was no handler for the signal, and since 222 * we only get here if there is a handler, we dont restart. 223 */ 224 restart = !has_handler; 225 break; 226 case ERESTARTSYS: 227 /* ERESTARTSYS means to restart the syscall if there is no 228 * handler or the handler was registered with SA_RESTART 229 */ 230 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 231 break; 232 case ERESTARTNOINTR: 233 /* ERESTARTNOINTR means that the syscall should be 234 * called again after the signal handler returns. 235 */ 236 break; 237 default: 238 return; 239 } 240 if (restart) { 241 if (ret == ERESTART_RESTARTBLOCK) 242 regs->gpr[0] = __NR_restart_syscall; 243 else 244 regs->gpr[3] = regs->orig_gpr3; 245 regs->nip -= 4; 246 regs->result = 0; 247 } else { 248 if (trap_is_scv(regs)) { 249 regs->result = -EINTR; 250 regs->gpr[3] = -EINTR; 251 } else { 252 regs->result = -EINTR; 253 regs->gpr[3] = EINTR; 254 regs->ccr |= 0x10000000; 255 } 256 } 257 } 258 259 static void do_signal(struct task_struct *tsk) 260 { 261 sigset_t *oldset = sigmask_to_save(); 262 struct ksignal ksig = { .sig = 0 }; 263 int ret; 264 265 BUG_ON(tsk != current); 266 267 get_signal(&ksig); 268 269 /* Is there any syscall restart business here ? */ 270 check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0); 271 272 if (ksig.sig <= 0) { 273 /* No signal to deliver -- put the saved sigmask back */ 274 restore_saved_sigmask(); 275 set_trap_norestart(tsk->thread.regs); 276 return; /* no signals delivered */ 277 } 278 279 /* 280 * Reenable the DABR before delivering the signal to 281 * user space. The DABR will have been cleared if it 282 * triggered inside the kernel. 283 */ 284 if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) { 285 int i; 286 287 for (i = 0; i < nr_wp_slots(); i++) { 288 if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type) 289 __set_breakpoint(i, &tsk->thread.hw_brk[i]); 290 } 291 } 292 293 /* Re-enable the breakpoints for the signal stack */ 294 thread_change_pc(tsk, tsk->thread.regs); 295 296 rseq_signal_deliver(&ksig, tsk->thread.regs); 297 298 if (is_32bit_task()) { 299 if (ksig.ka.sa.sa_flags & SA_SIGINFO) 300 ret = handle_rt_signal32(&ksig, oldset, tsk); 301 else 302 ret = handle_signal32(&ksig, oldset, tsk); 303 } else { 304 ret = handle_rt_signal64(&ksig, oldset, tsk); 305 } 306 307 set_trap_norestart(tsk->thread.regs); 308 signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP)); 309 } 310 311 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 312 { 313 user_exit(); 314 315 /* Check valid addr_limit, TIF check is done there */ 316 addr_limit_user_check(); 317 318 if (thread_info_flags & _TIF_UPROBE) 319 uprobe_notify_resume(regs); 320 321 if (thread_info_flags & _TIF_PATCH_PENDING) 322 klp_update_patch_state(current); 323 324 if (thread_info_flags & _TIF_SIGPENDING) { 325 BUG_ON(regs != current->thread.regs); 326 do_signal(current); 327 } 328 329 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 330 clear_thread_flag(TIF_NOTIFY_RESUME); 331 tracehook_notify_resume(regs); 332 rseq_handle_notify_resume(NULL, regs); 333 } 334 335 user_enter(); 336 } 337 338 unsigned long get_tm_stackpointer(struct task_struct *tsk) 339 { 340 /* When in an active transaction that takes a signal, we need to be 341 * careful with the stack. It's possible that the stack has moved back 342 * up after the tbegin. The obvious case here is when the tbegin is 343 * called inside a function that returns before a tend. In this case, 344 * the stack is part of the checkpointed transactional memory state. 345 * If we write over this non transactionally or in suspend, we are in 346 * trouble because if we get a tm abort, the program counter and stack 347 * pointer will be back at the tbegin but our in memory stack won't be 348 * valid anymore. 349 * 350 * To avoid this, when taking a signal in an active transaction, we 351 * need to use the stack pointer from the checkpointed state, rather 352 * than the speculated state. This ensures that the signal context 353 * (written tm suspended) will be written below the stack required for 354 * the rollback. The transaction is aborted because of the treclaim, 355 * so any memory written between the tbegin and the signal will be 356 * rolled back anyway. 357 * 358 * For signals taken in non-TM or suspended mode, we use the 359 * normal/non-checkpointed stack pointer. 360 */ 361 362 unsigned long ret = tsk->thread.regs->gpr[1]; 363 364 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 365 BUG_ON(tsk != current); 366 367 if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) { 368 preempt_disable(); 369 tm_reclaim_current(TM_CAUSE_SIGNAL); 370 if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr)) 371 ret = tsk->thread.ckpt_regs.gpr[1]; 372 373 /* 374 * If we treclaim, we must clear the current thread's TM bits 375 * before re-enabling preemption. Otherwise we might be 376 * preempted and have the live MSR[TS] changed behind our back 377 * (tm_recheckpoint_new_task() would recheckpoint). Besides, we 378 * enter the signal handler in non-transactional state. 379 */ 380 tsk->thread.regs->msr &= ~MSR_TS_MASK; 381 preempt_enable(); 382 } 383 #endif 384 return ret; 385 } 386