1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/arch/alpha/kernel/process.c 4 * 5 * Copyright (C) 1995 Linus Torvalds 6 */ 7 8 /* 9 * This file handles the architecture-dependent parts of process handling. 10 */ 11 12 #include <linux/errno.h> 13 #include <linux/module.h> 14 #include <linux/sched.h> 15 #include <linux/sched/debug.h> 16 #include <linux/sched/task.h> 17 #include <linux/sched/task_stack.h> 18 #include <linux/kernel.h> 19 #include <linux/mm.h> 20 #include <linux/smp.h> 21 #include <linux/stddef.h> 22 #include <linux/unistd.h> 23 #include <linux/ptrace.h> 24 #include <linux/user.h> 25 #include <linux/time.h> 26 #include <linux/major.h> 27 #include <linux/stat.h> 28 #include <linux/vt.h> 29 #include <linux/mman.h> 30 #include <linux/elfcore.h> 31 #include <linux/reboot.h> 32 #include <linux/tty.h> 33 #include <linux/console.h> 34 #include <linux/slab.h> 35 #include <linux/rcupdate.h> 36 37 #include <asm/reg.h> 38 #include <linux/uaccess.h> 39 #include <asm/io.h> 40 #include <asm/hwrpb.h> 41 #include <asm/fpu.h> 42 43 #include "proto.h" 44 #include "pci_impl.h" 45 46 /* 47 * Power off function, if any 48 */ 49 void (*pm_power_off)(void) = machine_power_off; 50 EXPORT_SYMBOL(pm_power_off); 51 52 #ifdef CONFIG_ALPHA_WTINT 53 /* 54 * Sleep the CPU. 55 * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts. 56 */ 57 void arch_cpu_idle(void) 58 { 59 wtint(0); 60 raw_local_irq_enable(); 61 } 62 63 void arch_cpu_idle_dead(void) 64 { 65 wtint(INT_MAX); 66 } 67 #endif /* ALPHA_WTINT */ 68 69 struct halt_info { 70 int mode; 71 char *restart_cmd; 72 }; 73 74 static void 75 common_shutdown_1(void *generic_ptr) 76 { 77 struct halt_info *how = (struct halt_info *)generic_ptr; 78 struct percpu_struct *cpup; 79 unsigned long *pflags, flags; 80 int cpuid = smp_processor_id(); 81 82 /* No point in taking interrupts anymore. */ 83 local_irq_disable(); 84 85 cpup = (struct percpu_struct *) 86 ((unsigned long)hwrpb + hwrpb->processor_offset 87 + hwrpb->processor_size * cpuid); 88 pflags = &cpup->flags; 89 flags = *pflags; 90 91 /* Clear reason to "default"; clear "bootstrap in progress". */ 92 flags &= ~0x00ff0001UL; 93 94 #ifdef CONFIG_SMP 95 /* Secondaries halt here. */ 96 if (cpuid != boot_cpuid) { 97 flags |= 0x00040000UL; /* "remain halted" */ 98 *pflags = flags; 99 set_cpu_present(cpuid, false); 100 set_cpu_possible(cpuid, false); 101 halt(); 102 } 103 #endif 104 105 if (how->mode == LINUX_REBOOT_CMD_RESTART) { 106 if (!how->restart_cmd) { 107 flags |= 0x00020000UL; /* "cold bootstrap" */ 108 } else { 109 /* For SRM, we could probably set environment 110 variables to get this to work. We'd have to 111 delay this until after srm_paging_stop unless 112 we ever got srm_fixup working. 113 114 At the moment, SRM will use the last boot device, 115 but the file and flags will be the defaults, when 116 doing a "warm" bootstrap. */ 117 flags |= 0x00030000UL; /* "warm bootstrap" */ 118 } 119 } else { 120 flags |= 0x00040000UL; /* "remain halted" */ 121 } 122 *pflags = flags; 123 124 #ifdef CONFIG_SMP 125 /* Wait for the secondaries to halt. */ 126 set_cpu_present(boot_cpuid, false); 127 set_cpu_possible(boot_cpuid, false); 128 while (cpumask_weight(cpu_present_mask)) 129 barrier(); 130 #endif 131 132 /* If booted from SRM, reset some of the original environment. */ 133 if (alpha_using_srm) { 134 #ifdef CONFIG_DUMMY_CONSOLE 135 /* If we've gotten here after SysRq-b, leave interrupt 136 context before taking over the console. */ 137 if (in_irq()) 138 irq_exit(); 139 /* This has the effect of resetting the VGA video origin. */ 140 console_lock(); 141 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 142 console_unlock(); 143 #endif 144 pci_restore_srm_config(); 145 set_hae(srm_hae); 146 } 147 148 if (alpha_mv.kill_arch) 149 alpha_mv.kill_arch(how->mode); 150 151 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 152 /* Unfortunately, since MILO doesn't currently understand 153 the hwrpb bits above, we can't reliably halt the 154 processor and keep it halted. So just loop. */ 155 return; 156 } 157 158 if (alpha_using_srm) 159 srm_paging_stop(); 160 161 halt(); 162 } 163 164 static void 165 common_shutdown(int mode, char *restart_cmd) 166 { 167 struct halt_info args; 168 args.mode = mode; 169 args.restart_cmd = restart_cmd; 170 on_each_cpu(common_shutdown_1, &args, 0); 171 } 172 173 void 174 machine_restart(char *restart_cmd) 175 { 176 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 177 } 178 179 180 void 181 machine_halt(void) 182 { 183 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 184 } 185 186 187 void 188 machine_power_off(void) 189 { 190 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 191 } 192 193 194 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 195 saved in the context it's used. */ 196 197 void 198 show_regs(struct pt_regs *regs) 199 { 200 show_regs_print_info(KERN_DEFAULT); 201 dik_show_regs(regs, NULL); 202 } 203 204 /* 205 * Re-start a thread when doing execve() 206 */ 207 void 208 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 209 { 210 regs->pc = pc; 211 regs->ps = 8; 212 wrusp(sp); 213 } 214 EXPORT_SYMBOL(start_thread); 215 216 void 217 flush_thread(void) 218 { 219 /* Arrange for each exec'ed process to start off with a clean slate 220 with respect to the FPU. This is all exceptions disabled. */ 221 current_thread_info()->ieee_state = 0; 222 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 223 224 /* Clean slate for TLS. */ 225 current_thread_info()->pcb.unique = 0; 226 } 227 228 void 229 release_thread(struct task_struct *dead_task) 230 { 231 } 232 233 /* 234 * Copy architecture-specific thread state 235 */ 236 int copy_thread(unsigned long clone_flags, unsigned long usp, 237 unsigned long kthread_arg, struct task_struct *p, 238 unsigned long tls) 239 { 240 extern void ret_from_fork(void); 241 extern void ret_from_kernel_thread(void); 242 243 struct thread_info *childti = task_thread_info(p); 244 struct pt_regs *childregs = task_pt_regs(p); 245 struct pt_regs *regs = current_pt_regs(); 246 struct switch_stack *childstack, *stack; 247 248 childstack = ((struct switch_stack *) childregs) - 1; 249 childti->pcb.ksp = (unsigned long) childstack; 250 childti->pcb.flags = 1; /* set FEN, clear everything else */ 251 252 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { 253 /* kernel thread */ 254 memset(childstack, 0, 255 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 256 childstack->r26 = (unsigned long) ret_from_kernel_thread; 257 childstack->r9 = usp; /* function */ 258 childstack->r10 = kthread_arg; 259 childregs->hae = alpha_mv.hae_cache, 260 childti->pcb.usp = 0; 261 return 0; 262 } 263 /* Note: if CLONE_SETTLS is not set, then we must inherit the 264 value from the parent, which will have been set by the block 265 copy in dup_task_struct. This is non-intuitive, but is 266 required for proper operation in the case of a threaded 267 application calling fork. */ 268 if (clone_flags & CLONE_SETTLS) 269 childti->pcb.unique = tls; 270 else 271 regs->r20 = 0; /* OSF/1 has some strange fork() semantics. */ 272 childti->pcb.usp = usp ?: rdusp(); 273 *childregs = *regs; 274 childregs->r0 = 0; 275 childregs->r19 = 0; 276 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 277 stack = ((struct switch_stack *) regs) - 1; 278 *childstack = *stack; 279 childstack->r26 = (unsigned long) ret_from_fork; 280 return 0; 281 } 282 283 /* 284 * Fill in the user structure for a ELF core dump. 285 */ 286 void 287 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 288 { 289 /* switch stack follows right below pt_regs: */ 290 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 291 292 dest[ 0] = pt->r0; 293 dest[ 1] = pt->r1; 294 dest[ 2] = pt->r2; 295 dest[ 3] = pt->r3; 296 dest[ 4] = pt->r4; 297 dest[ 5] = pt->r5; 298 dest[ 6] = pt->r6; 299 dest[ 7] = pt->r7; 300 dest[ 8] = pt->r8; 301 dest[ 9] = sw->r9; 302 dest[10] = sw->r10; 303 dest[11] = sw->r11; 304 dest[12] = sw->r12; 305 dest[13] = sw->r13; 306 dest[14] = sw->r14; 307 dest[15] = sw->r15; 308 dest[16] = pt->r16; 309 dest[17] = pt->r17; 310 dest[18] = pt->r18; 311 dest[19] = pt->r19; 312 dest[20] = pt->r20; 313 dest[21] = pt->r21; 314 dest[22] = pt->r22; 315 dest[23] = pt->r23; 316 dest[24] = pt->r24; 317 dest[25] = pt->r25; 318 dest[26] = pt->r26; 319 dest[27] = pt->r27; 320 dest[28] = pt->r28; 321 dest[29] = pt->gp; 322 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 323 dest[31] = pt->pc; 324 325 /* Once upon a time this was the PS value. Which is stupid 326 since that is always 8 for usermode. Usurped for the more 327 useful value of the thread's UNIQUE field. */ 328 dest[32] = ti->pcb.unique; 329 } 330 EXPORT_SYMBOL(dump_elf_thread); 331 332 int 333 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 334 { 335 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 336 return 1; 337 } 338 EXPORT_SYMBOL(dump_elf_task); 339 340 int 341 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 342 { 343 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 344 memcpy(dest, sw->fp, 32 * 8); 345 return 1; 346 } 347 EXPORT_SYMBOL(dump_elf_task_fp); 348 349 /* 350 * Return saved PC of a blocked thread. This assumes the frame 351 * pointer is the 6th saved long on the kernel stack and that the 352 * saved return address is the first long in the frame. This all 353 * holds provided the thread blocked through a call to schedule() ($15 354 * is the frame pointer in schedule() and $15 is saved at offset 48 by 355 * entry.S:do_switch_stack). 356 * 357 * Under heavy swap load I've seen this lose in an ugly way. So do 358 * some extra sanity checking on the ranges we expect these pointers 359 * to be in so that we can fail gracefully. This is just for ps after 360 * all. -- r~ 361 */ 362 363 static unsigned long 364 thread_saved_pc(struct task_struct *t) 365 { 366 unsigned long base = (unsigned long)task_stack_page(t); 367 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 368 369 if (sp > base && sp+6*8 < base + 16*1024) { 370 fp = ((unsigned long*)sp)[6]; 371 if (fp > sp && fp < base + 16*1024) 372 return *(unsigned long *)fp; 373 } 374 375 return 0; 376 } 377 378 unsigned long 379 get_wchan(struct task_struct *p) 380 { 381 unsigned long schedule_frame; 382 unsigned long pc; 383 if (!p || p == current || p->state == TASK_RUNNING) 384 return 0; 385 /* 386 * This one depends on the frame size of schedule(). Do a 387 * "disass schedule" in gdb to find the frame size. Also, the 388 * code assumes that sleep_on() follows immediately after 389 * interruptible_sleep_on() and that add_timer() follows 390 * immediately after interruptible_sleep(). Ugly, isn't it? 391 * Maybe adding a wchan field to task_struct would be better, 392 * after all... 393 */ 394 395 pc = thread_saved_pc(p); 396 if (in_sched_functions(pc)) { 397 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 398 return ((unsigned long *)schedule_frame)[12]; 399 } 400 return pc; 401 } 402