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/cpu.h> 13 #include <linux/errno.h> 14 #include <linux/module.h> 15 #include <linux/sched.h> 16 #include <linux/sched/debug.h> 17 #include <linux/sched/task.h> 18 #include <linux/sched/task_stack.h> 19 #include <linux/kernel.h> 20 #include <linux/mm.h> 21 #include <linux/smp.h> 22 #include <linux/stddef.h> 23 #include <linux/unistd.h> 24 #include <linux/ptrace.h> 25 #include <linux/user.h> 26 #include <linux/time.h> 27 #include <linux/major.h> 28 #include <linux/stat.h> 29 #include <linux/vt.h> 30 #include <linux/mman.h> 31 #include <linux/elfcore.h> 32 #include <linux/reboot.h> 33 #include <linux/tty.h> 34 #include <linux/console.h> 35 #include <linux/slab.h> 36 #include <linux/rcupdate.h> 37 38 #include <asm/reg.h> 39 #include <linux/uaccess.h> 40 #include <asm/io.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 } 62 63 void __noreturn arch_cpu_idle_dead(void) 64 { 65 wtint(INT_MAX); 66 BUG(); 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 = 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_empty(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_hardirq()) 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 /* 230 * Copy architecture-specific thread state 231 */ 232 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 233 { 234 unsigned long clone_flags = args->flags; 235 unsigned long usp = args->stack; 236 unsigned long tls = args->tls; 237 extern void ret_from_fork(void); 238 extern void ret_from_kernel_thread(void); 239 240 struct thread_info *childti = task_thread_info(p); 241 struct pt_regs *childregs = task_pt_regs(p); 242 struct pt_regs *regs = current_pt_regs(); 243 struct switch_stack *childstack, *stack; 244 245 childstack = ((struct switch_stack *) childregs) - 1; 246 childti->pcb.ksp = (unsigned long) childstack; 247 childti->pcb.flags = 1; /* set FEN, clear everything else */ 248 childti->status |= TS_SAVED_FP | TS_RESTORE_FP; 249 250 if (unlikely(args->fn)) { 251 /* kernel thread */ 252 memset(childstack, 0, 253 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 254 childstack->r26 = (unsigned long) ret_from_kernel_thread; 255 childstack->r9 = (unsigned long) args->fn; 256 childstack->r10 = (unsigned long) args->fn_arg; 257 childregs->hae = alpha_mv.hae_cache; 258 memset(childti->fp, '\0', sizeof(childti->fp)); 259 childti->pcb.usp = 0; 260 return 0; 261 } 262 /* Note: if CLONE_SETTLS is not set, then we must inherit the 263 value from the parent, which will have been set by the block 264 copy in dup_task_struct. This is non-intuitive, but is 265 required for proper operation in the case of a threaded 266 application calling fork. */ 267 if (clone_flags & CLONE_SETTLS) 268 childti->pcb.unique = tls; 269 else 270 regs->r20 = 0; /* OSF/1 has some strange fork() semantics. */ 271 childti->pcb.usp = usp ?: rdusp(); 272 *childregs = *regs; 273 childregs->r0 = 0; 274 childregs->r19 = 0; 275 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 276 stack = ((struct switch_stack *) regs) - 1; 277 *childstack = *stack; 278 childstack->r26 = (unsigned long) ret_from_fork; 279 return 0; 280 } 281 282 /* 283 * Fill in the user structure for a ELF core dump. 284 */ 285 void 286 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 287 { 288 /* switch stack follows right below pt_regs: */ 289 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 290 291 dest[ 0] = pt->r0; 292 dest[ 1] = pt->r1; 293 dest[ 2] = pt->r2; 294 dest[ 3] = pt->r3; 295 dest[ 4] = pt->r4; 296 dest[ 5] = pt->r5; 297 dest[ 6] = pt->r6; 298 dest[ 7] = pt->r7; 299 dest[ 8] = pt->r8; 300 dest[ 9] = sw->r9; 301 dest[10] = sw->r10; 302 dest[11] = sw->r11; 303 dest[12] = sw->r12; 304 dest[13] = sw->r13; 305 dest[14] = sw->r14; 306 dest[15] = sw->r15; 307 dest[16] = pt->r16; 308 dest[17] = pt->r17; 309 dest[18] = pt->r18; 310 dest[19] = pt->r19; 311 dest[20] = pt->r20; 312 dest[21] = pt->r21; 313 dest[22] = pt->r22; 314 dest[23] = pt->r23; 315 dest[24] = pt->r24; 316 dest[25] = pt->r25; 317 dest[26] = pt->r26; 318 dest[27] = pt->r27; 319 dest[28] = pt->r28; 320 dest[29] = pt->gp; 321 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 322 dest[31] = pt->pc; 323 324 /* Once upon a time this was the PS value. Which is stupid 325 since that is always 8 for usermode. Usurped for the more 326 useful value of the thread's UNIQUE field. */ 327 dest[32] = ti->pcb.unique; 328 } 329 EXPORT_SYMBOL(dump_elf_thread); 330 331 int 332 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 333 { 334 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 335 return 1; 336 } 337 EXPORT_SYMBOL(dump_elf_task); 338 339 int elf_core_copy_task_fpregs(struct task_struct *t, elf_fpregset_t *fpu) 340 { 341 memcpy(fpu, task_thread_info(t)->fp, 32 * 8); 342 return 1; 343 } 344 345 /* 346 * Return saved PC of a blocked thread. This assumes the frame 347 * pointer is the 6th saved long on the kernel stack and that the 348 * saved return address is the first long in the frame. This all 349 * holds provided the thread blocked through a call to schedule() ($15 350 * is the frame pointer in schedule() and $15 is saved at offset 48 by 351 * entry.S:do_switch_stack). 352 * 353 * Under heavy swap load I've seen this lose in an ugly way. So do 354 * some extra sanity checking on the ranges we expect these pointers 355 * to be in so that we can fail gracefully. This is just for ps after 356 * all. -- r~ 357 */ 358 359 static unsigned long 360 thread_saved_pc(struct task_struct *t) 361 { 362 unsigned long base = (unsigned long)task_stack_page(t); 363 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 364 365 if (sp > base && sp+6*8 < base + 16*1024) { 366 fp = ((unsigned long*)sp)[6]; 367 if (fp > sp && fp < base + 16*1024) 368 return *(unsigned long *)fp; 369 } 370 371 return 0; 372 } 373 374 unsigned long 375 __get_wchan(struct task_struct *p) 376 { 377 unsigned long schedule_frame; 378 unsigned long pc; 379 380 /* 381 * This one depends on the frame size of schedule(). Do a 382 * "disass schedule" in gdb to find the frame size. Also, the 383 * code assumes that sleep_on() follows immediately after 384 * interruptible_sleep_on() and that add_timer() follows 385 * immediately after interruptible_sleep(). Ugly, isn't it? 386 * Maybe adding a wchan field to task_struct would be better, 387 * after all... 388 */ 389 390 pc = thread_saved_pc(p); 391 if (in_sched_functions(pc)) { 392 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 393 return ((unsigned long *)schedule_frame)[12]; 394 } 395 return pc; 396 } 397