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/pgtable.h> 41 #include <asm/hwrpb.h> 42 #include <asm/fpu.h> 43 44 #include "proto.h" 45 #include "pci_impl.h" 46 47 /* 48 * Power off function, if any 49 */ 50 void (*pm_power_off)(void) = machine_power_off; 51 EXPORT_SYMBOL(pm_power_off); 52 53 #ifdef CONFIG_ALPHA_WTINT 54 /* 55 * Sleep the CPU. 56 * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts. 57 */ 58 void arch_cpu_idle(void) 59 { 60 wtint(0); 61 local_irq_enable(); 62 } 63 64 void arch_cpu_idle_dead(void) 65 { 66 wtint(INT_MAX); 67 } 68 #endif /* ALPHA_WTINT */ 69 70 struct halt_info { 71 int mode; 72 char *restart_cmd; 73 }; 74 75 static void 76 common_shutdown_1(void *generic_ptr) 77 { 78 struct halt_info *how = (struct halt_info *)generic_ptr; 79 struct percpu_struct *cpup; 80 unsigned long *pflags, flags; 81 int cpuid = smp_processor_id(); 82 83 /* No point in taking interrupts anymore. */ 84 local_irq_disable(); 85 86 cpup = (struct percpu_struct *) 87 ((unsigned long)hwrpb + hwrpb->processor_offset 88 + hwrpb->processor_size * cpuid); 89 pflags = &cpup->flags; 90 flags = *pflags; 91 92 /* Clear reason to "default"; clear "bootstrap in progress". */ 93 flags &= ~0x00ff0001UL; 94 95 #ifdef CONFIG_SMP 96 /* Secondaries halt here. */ 97 if (cpuid != boot_cpuid) { 98 flags |= 0x00040000UL; /* "remain halted" */ 99 *pflags = flags; 100 set_cpu_present(cpuid, false); 101 set_cpu_possible(cpuid, false); 102 halt(); 103 } 104 #endif 105 106 if (how->mode == LINUX_REBOOT_CMD_RESTART) { 107 if (!how->restart_cmd) { 108 flags |= 0x00020000UL; /* "cold bootstrap" */ 109 } else { 110 /* For SRM, we could probably set environment 111 variables to get this to work. We'd have to 112 delay this until after srm_paging_stop unless 113 we ever got srm_fixup working. 114 115 At the moment, SRM will use the last boot device, 116 but the file and flags will be the defaults, when 117 doing a "warm" bootstrap. */ 118 flags |= 0x00030000UL; /* "warm bootstrap" */ 119 } 120 } else { 121 flags |= 0x00040000UL; /* "remain halted" */ 122 } 123 *pflags = flags; 124 125 #ifdef CONFIG_SMP 126 /* Wait for the secondaries to halt. */ 127 set_cpu_present(boot_cpuid, false); 128 set_cpu_possible(boot_cpuid, false); 129 while (cpumask_weight(cpu_present_mask)) 130 barrier(); 131 #endif 132 133 /* If booted from SRM, reset some of the original environment. */ 134 if (alpha_using_srm) { 135 #ifdef CONFIG_DUMMY_CONSOLE 136 /* If we've gotten here after SysRq-b, leave interrupt 137 context before taking over the console. */ 138 if (in_interrupt()) 139 irq_exit(); 140 /* This has the effect of resetting the VGA video origin. */ 141 console_lock(); 142 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 143 console_unlock(); 144 #endif 145 pci_restore_srm_config(); 146 set_hae(srm_hae); 147 } 148 149 if (alpha_mv.kill_arch) 150 alpha_mv.kill_arch(how->mode); 151 152 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 153 /* Unfortunately, since MILO doesn't currently understand 154 the hwrpb bits above, we can't reliably halt the 155 processor and keep it halted. So just loop. */ 156 return; 157 } 158 159 if (alpha_using_srm) 160 srm_paging_stop(); 161 162 halt(); 163 } 164 165 static void 166 common_shutdown(int mode, char *restart_cmd) 167 { 168 struct halt_info args; 169 args.mode = mode; 170 args.restart_cmd = restart_cmd; 171 on_each_cpu(common_shutdown_1, &args, 0); 172 } 173 174 void 175 machine_restart(char *restart_cmd) 176 { 177 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 178 } 179 180 181 void 182 machine_halt(void) 183 { 184 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 185 } 186 187 188 void 189 machine_power_off(void) 190 { 191 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 192 } 193 194 195 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 196 saved in the context it's used. */ 197 198 void 199 show_regs(struct pt_regs *regs) 200 { 201 show_regs_print_info(KERN_DEFAULT); 202 dik_show_regs(regs, NULL); 203 } 204 205 /* 206 * Re-start a thread when doing execve() 207 */ 208 void 209 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 210 { 211 regs->pc = pc; 212 regs->ps = 8; 213 wrusp(sp); 214 } 215 EXPORT_SYMBOL(start_thread); 216 217 void 218 flush_thread(void) 219 { 220 /* Arrange for each exec'ed process to start off with a clean slate 221 with respect to the FPU. This is all exceptions disabled. */ 222 current_thread_info()->ieee_state = 0; 223 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 224 225 /* Clean slate for TLS. */ 226 current_thread_info()->pcb.unique = 0; 227 } 228 229 void 230 release_thread(struct task_struct *dead_task) 231 { 232 } 233 234 /* 235 * Copy architecture-specific thread state 236 */ 237 int 238 copy_thread(unsigned long clone_flags, unsigned long usp, 239 unsigned long kthread_arg, 240 struct task_struct *p) 241 { 242 extern void ret_from_fork(void); 243 extern void ret_from_kernel_thread(void); 244 245 struct thread_info *childti = task_thread_info(p); 246 struct pt_regs *childregs = task_pt_regs(p); 247 struct pt_regs *regs = current_pt_regs(); 248 struct switch_stack *childstack, *stack; 249 250 childstack = ((struct switch_stack *) childregs) - 1; 251 childti->pcb.ksp = (unsigned long) childstack; 252 childti->pcb.flags = 1; /* set FEN, clear everything else */ 253 254 if (unlikely(p->flags & PF_KTHREAD)) { 255 /* kernel thread */ 256 memset(childstack, 0, 257 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 258 childstack->r26 = (unsigned long) ret_from_kernel_thread; 259 childstack->r9 = usp; /* function */ 260 childstack->r10 = kthread_arg; 261 childregs->hae = alpha_mv.hae_cache, 262 childti->pcb.usp = 0; 263 return 0; 264 } 265 /* Note: if CLONE_SETTLS is not set, then we must inherit the 266 value from the parent, which will have been set by the block 267 copy in dup_task_struct. This is non-intuitive, but is 268 required for proper operation in the case of a threaded 269 application calling fork. */ 270 if (clone_flags & CLONE_SETTLS) 271 childti->pcb.unique = regs->r20; 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 regs->r20 = 0; 278 stack = ((struct switch_stack *) regs) - 1; 279 *childstack = *stack; 280 childstack->r26 = (unsigned long) ret_from_fork; 281 return 0; 282 } 283 284 /* 285 * Fill in the user structure for a ELF core dump. 286 */ 287 void 288 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 289 { 290 /* switch stack follows right below pt_regs: */ 291 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 292 293 dest[ 0] = pt->r0; 294 dest[ 1] = pt->r1; 295 dest[ 2] = pt->r2; 296 dest[ 3] = pt->r3; 297 dest[ 4] = pt->r4; 298 dest[ 5] = pt->r5; 299 dest[ 6] = pt->r6; 300 dest[ 7] = pt->r7; 301 dest[ 8] = pt->r8; 302 dest[ 9] = sw->r9; 303 dest[10] = sw->r10; 304 dest[11] = sw->r11; 305 dest[12] = sw->r12; 306 dest[13] = sw->r13; 307 dest[14] = sw->r14; 308 dest[15] = sw->r15; 309 dest[16] = pt->r16; 310 dest[17] = pt->r17; 311 dest[18] = pt->r18; 312 dest[19] = pt->r19; 313 dest[20] = pt->r20; 314 dest[21] = pt->r21; 315 dest[22] = pt->r22; 316 dest[23] = pt->r23; 317 dest[24] = pt->r24; 318 dest[25] = pt->r25; 319 dest[26] = pt->r26; 320 dest[27] = pt->r27; 321 dest[28] = pt->r28; 322 dest[29] = pt->gp; 323 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 324 dest[31] = pt->pc; 325 326 /* Once upon a time this was the PS value. Which is stupid 327 since that is always 8 for usermode. Usurped for the more 328 useful value of the thread's UNIQUE field. */ 329 dest[32] = ti->pcb.unique; 330 } 331 EXPORT_SYMBOL(dump_elf_thread); 332 333 int 334 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 335 { 336 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 337 return 1; 338 } 339 EXPORT_SYMBOL(dump_elf_task); 340 341 int 342 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 343 { 344 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 345 memcpy(dest, sw->fp, 32 * 8); 346 return 1; 347 } 348 EXPORT_SYMBOL(dump_elf_task_fp); 349 350 /* 351 * Return saved PC of a blocked thread. This assumes the frame 352 * pointer is the 6th saved long on the kernel stack and that the 353 * saved return address is the first long in the frame. This all 354 * holds provided the thread blocked through a call to schedule() ($15 355 * is the frame pointer in schedule() and $15 is saved at offset 48 by 356 * entry.S:do_switch_stack). 357 * 358 * Under heavy swap load I've seen this lose in an ugly way. So do 359 * some extra sanity checking on the ranges we expect these pointers 360 * to be in so that we can fail gracefully. This is just for ps after 361 * all. -- r~ 362 */ 363 364 unsigned long 365 thread_saved_pc(struct task_struct *t) 366 { 367 unsigned long base = (unsigned long)task_stack_page(t); 368 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 369 370 if (sp > base && sp+6*8 < base + 16*1024) { 371 fp = ((unsigned long*)sp)[6]; 372 if (fp > sp && fp < base + 16*1024) 373 return *(unsigned long *)fp; 374 } 375 376 return 0; 377 } 378 379 unsigned long 380 get_wchan(struct task_struct *p) 381 { 382 unsigned long schedule_frame; 383 unsigned long pc; 384 if (!p || p == current || p->state == TASK_RUNNING) 385 return 0; 386 /* 387 * This one depends on the frame size of schedule(). Do a 388 * "disass schedule" in gdb to find the frame size. Also, the 389 * code assumes that sleep_on() follows immediately after 390 * interruptible_sleep_on() and that add_timer() follows 391 * immediately after interruptible_sleep(). Ugly, isn't it? 392 * Maybe adding a wchan field to task_struct would be better, 393 * after all... 394 */ 395 396 pc = thread_saved_pc(p); 397 if (in_sched_functions(pc)) { 398 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 399 return ((unsigned long *)schedule_frame)[12]; 400 } 401 return pc; 402 } 403