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 void
229 release_thread(struct task_struct *dead_task)
230 {
231 }
232
233 /*
234 * Copy architecture-specific thread state
235 */
236 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
237 {
238 unsigned long clone_flags = args->flags;
239 unsigned long usp = args->stack;
240 unsigned long tls = args->tls;
241 extern void ret_from_fork(void);
242 extern void ret_from_kernel_thread(void);
243
244 struct thread_info *childti = task_thread_info(p);
245 struct pt_regs *childregs = task_pt_regs(p);
246 struct pt_regs *regs = current_pt_regs();
247 struct switch_stack *childstack, *stack;
248
249 childstack = ((struct switch_stack *) childregs) - 1;
250 childti->pcb.ksp = (unsigned long) childstack;
251 childti->pcb.flags = 1; /* set FEN, clear everything else */
252
253 if (unlikely(args->fn)) {
254 /* kernel thread */
255 memset(childstack, 0,
256 sizeof(struct switch_stack) + sizeof(struct pt_regs));
257 childstack->r26 = (unsigned long) ret_from_kernel_thread;
258 childstack->r9 = (unsigned long) args->fn;
259 childstack->r10 = (unsigned long) args->fn_arg;
260 childregs->hae = alpha_mv.hae_cache;
261 childti->pcb.usp = 0;
262 return 0;
263 }
264 /* Note: if CLONE_SETTLS is not set, then we must inherit the
265 value from the parent, which will have been set by the block
266 copy in dup_task_struct. This is non-intuitive, but is
267 required for proper operation in the case of a threaded
268 application calling fork. */
269 if (clone_flags & CLONE_SETTLS)
270 childti->pcb.unique = tls;
271 else
272 regs->r20 = 0; /* OSF/1 has some strange fork() semantics. */
273 childti->pcb.usp = usp ?: rdusp();
274 *childregs = *regs;
275 childregs->r0 = 0;
276 childregs->r19 = 0;
277 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
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 static 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
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
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