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/resume_user_mode.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 #endif 137 138 /* Log an error when sending an unhandled signal to a process. Controlled 139 * through debug.exception-trace sysctl. 140 */ 141 142 int show_unhandled_signals = 1; 143 144 unsigned long get_min_sigframe_size(void) 145 { 146 if (IS_ENABLED(CONFIG_PPC64)) 147 return get_min_sigframe_size_64(); 148 else 149 return get_min_sigframe_size_32(); 150 } 151 152 #ifdef CONFIG_COMPAT 153 unsigned long get_min_sigframe_size_compat(void) 154 { 155 return get_min_sigframe_size_32(); 156 } 157 #endif 158 159 /* 160 * Allocate space for the signal frame 161 */ 162 static unsigned long get_tm_stackpointer(struct task_struct *tsk); 163 164 void __user *get_sigframe(struct ksignal *ksig, struct task_struct *tsk, 165 size_t frame_size, int is_32) 166 { 167 unsigned long oldsp, newsp; 168 unsigned long sp = get_tm_stackpointer(tsk); 169 170 /* Default to using normal stack */ 171 if (is_32) 172 oldsp = sp & 0x0ffffffffUL; 173 else 174 oldsp = sp; 175 oldsp = sigsp(oldsp, ksig); 176 newsp = (oldsp - frame_size) & ~0xFUL; 177 178 return (void __user *)newsp; 179 } 180 181 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 182 int has_handler) 183 { 184 unsigned long ret = regs->gpr[3]; 185 int restart = 1; 186 187 /* syscall ? */ 188 if (!trap_is_syscall(regs)) 189 return; 190 191 if (trap_norestart(regs)) 192 return; 193 194 /* error signalled ? */ 195 if (trap_is_scv(regs)) { 196 /* 32-bit compat mode sign extend? */ 197 if (!IS_ERR_VALUE(ret)) 198 return; 199 ret = -ret; 200 } else if (!(regs->ccr & 0x10000000)) { 201 return; 202 } 203 204 switch (ret) { 205 case ERESTART_RESTARTBLOCK: 206 case ERESTARTNOHAND: 207 /* ERESTARTNOHAND means that the syscall should only be 208 * restarted if there was no handler for the signal, and since 209 * we only get here if there is a handler, we dont restart. 210 */ 211 restart = !has_handler; 212 break; 213 case ERESTARTSYS: 214 /* ERESTARTSYS means to restart the syscall if there is no 215 * handler or the handler was registered with SA_RESTART 216 */ 217 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 218 break; 219 case ERESTARTNOINTR: 220 /* ERESTARTNOINTR means that the syscall should be 221 * called again after the signal handler returns. 222 */ 223 break; 224 default: 225 return; 226 } 227 if (restart) { 228 if (ret == ERESTART_RESTARTBLOCK) 229 regs->gpr[0] = __NR_restart_syscall; 230 else 231 regs->gpr[3] = regs->orig_gpr3; 232 regs_add_return_ip(regs, -4); 233 regs->result = 0; 234 } else { 235 if (trap_is_scv(regs)) { 236 regs->result = -EINTR; 237 regs->gpr[3] = -EINTR; 238 } else { 239 regs->result = -EINTR; 240 regs->gpr[3] = EINTR; 241 regs->ccr |= 0x10000000; 242 } 243 } 244 } 245 246 static void do_signal(struct task_struct *tsk) 247 { 248 sigset_t *oldset = sigmask_to_save(); 249 struct ksignal ksig = { .sig = 0 }; 250 int ret; 251 252 BUG_ON(tsk != current); 253 254 get_signal(&ksig); 255 256 /* Is there any syscall restart business here ? */ 257 check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0); 258 259 if (ksig.sig <= 0) { 260 /* No signal to deliver -- put the saved sigmask back */ 261 restore_saved_sigmask(); 262 set_trap_norestart(tsk->thread.regs); 263 return; /* no signals delivered */ 264 } 265 266 /* 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 (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) { 272 int i; 273 274 for (i = 0; i < nr_wp_slots(); i++) { 275 if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type) 276 __set_breakpoint(i, &tsk->thread.hw_brk[i]); 277 } 278 } 279 280 /* Re-enable the breakpoints for the signal stack */ 281 thread_change_pc(tsk, tsk->thread.regs); 282 283 rseq_signal_deliver(&ksig, tsk->thread.regs); 284 285 if (is_32bit_task()) { 286 if (ksig.ka.sa.sa_flags & SA_SIGINFO) 287 ret = handle_rt_signal32(&ksig, oldset, tsk); 288 else 289 ret = handle_signal32(&ksig, oldset, tsk); 290 } else { 291 ret = handle_rt_signal64(&ksig, oldset, tsk); 292 } 293 294 set_trap_norestart(tsk->thread.regs); 295 signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP)); 296 } 297 298 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 299 { 300 if (thread_info_flags & _TIF_UPROBE) 301 uprobe_notify_resume(regs); 302 303 if (thread_info_flags & _TIF_PATCH_PENDING) 304 klp_update_patch_state(current); 305 306 if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) { 307 BUG_ON(regs != current->thread.regs); 308 do_signal(current); 309 } 310 311 if (thread_info_flags & _TIF_NOTIFY_RESUME) 312 resume_user_mode_work(regs); 313 } 314 315 static unsigned long get_tm_stackpointer(struct task_struct *tsk) 316 { 317 /* When in an active transaction that takes a signal, we need to be 318 * careful with the stack. It's possible that the stack has moved back 319 * up after the tbegin. The obvious case here is when the tbegin is 320 * called inside a function that returns before a tend. In this case, 321 * the stack is part of the checkpointed transactional memory state. 322 * If we write over this non transactionally or in suspend, we are in 323 * trouble because if we get a tm abort, the program counter and stack 324 * pointer will be back at the tbegin but our in memory stack won't be 325 * valid anymore. 326 * 327 * To avoid this, when taking a signal in an active transaction, we 328 * need to use the stack pointer from the checkpointed state, rather 329 * than the speculated state. This ensures that the signal context 330 * (written tm suspended) will be written below the stack required for 331 * the rollback. The transaction is aborted because of the treclaim, 332 * so any memory written between the tbegin and the signal will be 333 * rolled back anyway. 334 * 335 * For signals taken in non-TM or suspended mode, we use the 336 * normal/non-checkpointed stack pointer. 337 */ 338 struct pt_regs *regs = tsk->thread.regs; 339 unsigned long ret = regs->gpr[1]; 340 341 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 342 BUG_ON(tsk != current); 343 344 if (MSR_TM_ACTIVE(regs->msr)) { 345 preempt_disable(); 346 tm_reclaim_current(TM_CAUSE_SIGNAL); 347 if (MSR_TM_TRANSACTIONAL(regs->msr)) 348 ret = tsk->thread.ckpt_regs.gpr[1]; 349 350 /* 351 * If we treclaim, we must clear the current thread's TM bits 352 * before re-enabling preemption. Otherwise we might be 353 * preempted and have the live MSR[TS] changed behind our back 354 * (tm_recheckpoint_new_task() would recheckpoint). Besides, we 355 * enter the signal handler in non-transactional state. 356 */ 357 regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK); 358 preempt_enable(); 359 } 360 #endif 361 return ret; 362 } 363 364 static const char fm32[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %08lx lr %08lx\n"; 365 static const char fm64[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %016lx lr %016lx\n"; 366 367 void signal_fault(struct task_struct *tsk, struct pt_regs *regs, 368 const char *where, void __user *ptr) 369 { 370 if (show_unhandled_signals) 371 printk_ratelimited(regs->msr & MSR_64BIT ? fm64 : fm32, tsk->comm, 372 task_pid_nr(tsk), where, ptr, regs->nip, regs->link); 373 } 374