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(regs) != 0x0C00) 202 return; 203 204 /* error signalled ? */ 205 if (!(regs->ccr & 0x10000000)) 206 return; 207 208 switch (ret) { 209 case ERESTART_RESTARTBLOCK: 210 case ERESTARTNOHAND: 211 /* ERESTARTNOHAND means that the syscall should only be 212 * restarted if there was no handler for the signal, and since 213 * we only get here if there is a handler, we dont restart. 214 */ 215 restart = !has_handler; 216 break; 217 case ERESTARTSYS: 218 /* ERESTARTSYS means to restart the syscall if there is no 219 * handler or the handler was registered with SA_RESTART 220 */ 221 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 222 break; 223 case ERESTARTNOINTR: 224 /* ERESTARTNOINTR means that the syscall should be 225 * called again after the signal handler returns. 226 */ 227 break; 228 default: 229 return; 230 } 231 if (restart) { 232 if (ret == ERESTART_RESTARTBLOCK) 233 regs->gpr[0] = __NR_restart_syscall; 234 else 235 regs->gpr[3] = regs->orig_gpr3; 236 regs->nip -= 4; 237 regs->result = 0; 238 } else { 239 regs->result = -EINTR; 240 regs->gpr[3] = EINTR; 241 regs->ccr |= 0x10000000; 242 } 243 } 244 245 static void do_signal(struct task_struct *tsk) 246 { 247 sigset_t *oldset = sigmask_to_save(); 248 struct ksignal ksig = { .sig = 0 }; 249 int ret; 250 251 BUG_ON(tsk != current); 252 253 get_signal(&ksig); 254 255 /* Is there any syscall restart business here ? */ 256 check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0); 257 258 if (ksig.sig <= 0) { 259 /* No signal to deliver -- put the saved sigmask back */ 260 restore_saved_sigmask(); 261 tsk->thread.regs->trap = 0; 262 return; /* no signals delivered */ 263 } 264 265 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 266 /* 267 * Reenable the DABR before delivering the signal to 268 * user space. The DABR will have been cleared if it 269 * triggered inside the kernel. 270 */ 271 if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type) 272 __set_breakpoint(&tsk->thread.hw_brk); 273 #endif 274 /* Re-enable the breakpoints for the signal stack */ 275 thread_change_pc(tsk, tsk->thread.regs); 276 277 rseq_signal_deliver(&ksig, tsk->thread.regs); 278 279 if (is_32bit_task()) { 280 if (ksig.ka.sa.sa_flags & SA_SIGINFO) 281 ret = handle_rt_signal32(&ksig, oldset, tsk); 282 else 283 ret = handle_signal32(&ksig, oldset, tsk); 284 } else { 285 ret = handle_rt_signal64(&ksig, oldset, tsk); 286 } 287 288 tsk->thread.regs->trap = 0; 289 signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP)); 290 } 291 292 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 293 { 294 user_exit(); 295 296 /* Check valid addr_limit, TIF check is done there */ 297 addr_limit_user_check(); 298 299 if (thread_info_flags & _TIF_UPROBE) 300 uprobe_notify_resume(regs); 301 302 if (thread_info_flags & _TIF_PATCH_PENDING) 303 klp_update_patch_state(current); 304 305 if (thread_info_flags & _TIF_SIGPENDING) { 306 BUG_ON(regs != current->thread.regs); 307 do_signal(current); 308 } 309 310 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 311 clear_thread_flag(TIF_NOTIFY_RESUME); 312 tracehook_notify_resume(regs); 313 rseq_handle_notify_resume(NULL, regs); 314 } 315 316 user_enter(); 317 } 318 319 unsigned long get_tm_stackpointer(struct task_struct *tsk) 320 { 321 /* When in an active transaction that takes a signal, we need to be 322 * careful with the stack. It's possible that the stack has moved back 323 * up after the tbegin. The obvious case here is when the tbegin is 324 * called inside a function that returns before a tend. In this case, 325 * the stack is part of the checkpointed transactional memory state. 326 * If we write over this non transactionally or in suspend, we are in 327 * trouble because if we get a tm abort, the program counter and stack 328 * pointer will be back at the tbegin but our in memory stack won't be 329 * valid anymore. 330 * 331 * To avoid this, when taking a signal in an active transaction, we 332 * need to use the stack pointer from the checkpointed state, rather 333 * than the speculated state. This ensures that the signal context 334 * (written tm suspended) will be written below the stack required for 335 * the rollback. The transaction is aborted because of the treclaim, 336 * so any memory written between the tbegin and the signal will be 337 * rolled back anyway. 338 * 339 * For signals taken in non-TM or suspended mode, we use the 340 * normal/non-checkpointed stack pointer. 341 */ 342 343 unsigned long ret = tsk->thread.regs->gpr[1]; 344 345 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 346 BUG_ON(tsk != current); 347 348 if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) { 349 preempt_disable(); 350 tm_reclaim_current(TM_CAUSE_SIGNAL); 351 if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr)) 352 ret = tsk->thread.ckpt_regs.gpr[1]; 353 354 /* 355 * If we treclaim, we must clear the current thread's TM bits 356 * before re-enabling preemption. Otherwise we might be 357 * preempted and have the live MSR[TS] changed behind our back 358 * (tm_recheckpoint_new_task() would recheckpoint). Besides, we 359 * enter the signal handler in non-transactional state. 360 */ 361 tsk->thread.regs->msr &= ~MSR_TS_MASK; 362 preempt_enable(); 363 } 364 #endif 365 return ret; 366 } 367