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_empty(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 /* 229 * Copy architecture-specific thread state 230 */ 231 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 232 { 233 unsigned long clone_flags = args->flags; 234 unsigned long usp = args->stack; 235 unsigned long tls = args->tls; 236 extern void ret_from_fork(void); 237 extern void ret_from_kernel_thread(void); 238 239 struct thread_info *childti = task_thread_info(p); 240 struct pt_regs *childregs = task_pt_regs(p); 241 struct pt_regs *regs = current_pt_regs(); 242 struct switch_stack *childstack, *stack; 243 244 childstack = ((struct switch_stack *) childregs) - 1; 245 childti->pcb.ksp = (unsigned long) childstack; 246 childti->pcb.flags = 1; /* set FEN, clear everything else */ 247 248 if (unlikely(args->fn)) { 249 /* kernel thread */ 250 memset(childstack, 0, 251 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 252 childstack->r26 = (unsigned long) ret_from_kernel_thread; 253 childstack->r9 = (unsigned long) args->fn; 254 childstack->r10 = (unsigned long) args->fn_arg; 255 childregs->hae = alpha_mv.hae_cache; 256 childti->pcb.usp = 0; 257 return 0; 258 } 259 /* Note: if CLONE_SETTLS is not set, then we must inherit the 260 value from the parent, which will have been set by the block 261 copy in dup_task_struct. This is non-intuitive, but is 262 required for proper operation in the case of a threaded 263 application calling fork. */ 264 if (clone_flags & CLONE_SETTLS) 265 childti->pcb.unique = tls; 266 else 267 regs->r20 = 0; /* OSF/1 has some strange fork() semantics. */ 268 childti->pcb.usp = usp ?: rdusp(); 269 *childregs = *regs; 270 childregs->r0 = 0; 271 childregs->r19 = 0; 272 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 273 stack = ((struct switch_stack *) regs) - 1; 274 *childstack = *stack; 275 childstack->r26 = (unsigned long) ret_from_fork; 276 return 0; 277 } 278 279 /* 280 * Fill in the user structure for a ELF core dump. 281 */ 282 void 283 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 284 { 285 /* switch stack follows right below pt_regs: */ 286 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 287 288 dest[ 0] = pt->r0; 289 dest[ 1] = pt->r1; 290 dest[ 2] = pt->r2; 291 dest[ 3] = pt->r3; 292 dest[ 4] = pt->r4; 293 dest[ 5] = pt->r5; 294 dest[ 6] = pt->r6; 295 dest[ 7] = pt->r7; 296 dest[ 8] = pt->r8; 297 dest[ 9] = sw->r9; 298 dest[10] = sw->r10; 299 dest[11] = sw->r11; 300 dest[12] = sw->r12; 301 dest[13] = sw->r13; 302 dest[14] = sw->r14; 303 dest[15] = sw->r15; 304 dest[16] = pt->r16; 305 dest[17] = pt->r17; 306 dest[18] = pt->r18; 307 dest[19] = pt->r19; 308 dest[20] = pt->r20; 309 dest[21] = pt->r21; 310 dest[22] = pt->r22; 311 dest[23] = pt->r23; 312 dest[24] = pt->r24; 313 dest[25] = pt->r25; 314 dest[26] = pt->r26; 315 dest[27] = pt->r27; 316 dest[28] = pt->r28; 317 dest[29] = pt->gp; 318 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 319 dest[31] = pt->pc; 320 321 /* Once upon a time this was the PS value. Which is stupid 322 since that is always 8 for usermode. Usurped for the more 323 useful value of the thread's UNIQUE field. */ 324 dest[32] = ti->pcb.unique; 325 } 326 EXPORT_SYMBOL(dump_elf_thread); 327 328 int 329 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 330 { 331 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 332 return 1; 333 } 334 EXPORT_SYMBOL(dump_elf_task); 335 336 int elf_core_copy_task_fpregs(struct task_struct *t, elf_fpregset_t *fpu) 337 { 338 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(t) - 1; 339 memcpy(fpu, sw->fp, 32 * 8); 340 return 1; 341 } 342 343 /* 344 * Return saved PC of a blocked thread. This assumes the frame 345 * pointer is the 6th saved long on the kernel stack and that the 346 * saved return address is the first long in the frame. This all 347 * holds provided the thread blocked through a call to schedule() ($15 348 * is the frame pointer in schedule() and $15 is saved at offset 48 by 349 * entry.S:do_switch_stack). 350 * 351 * Under heavy swap load I've seen this lose in an ugly way. So do 352 * some extra sanity checking on the ranges we expect these pointers 353 * to be in so that we can fail gracefully. This is just for ps after 354 * all. -- r~ 355 */ 356 357 static unsigned long 358 thread_saved_pc(struct task_struct *t) 359 { 360 unsigned long base = (unsigned long)task_stack_page(t); 361 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 362 363 if (sp > base && sp+6*8 < base + 16*1024) { 364 fp = ((unsigned long*)sp)[6]; 365 if (fp > sp && fp < base + 16*1024) 366 return *(unsigned long *)fp; 367 } 368 369 return 0; 370 } 371 372 unsigned long 373 __get_wchan(struct task_struct *p) 374 { 375 unsigned long schedule_frame; 376 unsigned long pc; 377 378 /* 379 * This one depends on the frame size of schedule(). Do a 380 * "disass schedule" in gdb to find the frame size. Also, the 381 * code assumes that sleep_on() follows immediately after 382 * interruptible_sleep_on() and that add_timer() follows 383 * immediately after interruptible_sleep(). Ugly, isn't it? 384 * Maybe adding a wchan field to task_struct would be better, 385 * after all... 386 */ 387 388 pc = thread_saved_pc(p); 389 if (in_sched_functions(pc)) { 390 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 391 return ((unsigned long *)schedule_frame)[12]; 392 } 393 return pc; 394 } 395