process.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *    PARISC Architecture-dependent parts of process handling
  4 *    based on the work for i386
  5 *
  6 *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
  7 *    Copyright (C) 2000 Martin K Petersen <mkp at mkp.net>
  8 *    Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
  9 *    Copyright (C) 2000 David Huggins-Daines <dhd with pobox.org>
 10 *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
 11 *    Copyright (C) 2000 Philipp Rumpf <prumpf with tux.org>
 12 *    Copyright (C) 2000 David Kennedy <dkennedy with linuxcare.com>
 13 *    Copyright (C) 2000 Richard Hirst <rhirst with parisc-linux.org>
 14 *    Copyright (C) 2000 Grant Grundler <grundler with parisc-linux.org>
 15 *    Copyright (C) 2001 Alan Modra <amodra at parisc-linux.org>
 16 *    Copyright (C) 2001-2002 Ryan Bradetich <rbrad at parisc-linux.org>
 17 *    Copyright (C) 2001-2014 Helge Deller <deller@gmx.de>
 18 *    Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
 19 */
 20#include <linux/elf.h>
 21#include <linux/errno.h>
 22#include <linux/kernel.h>
 23#include <linux/mm.h>
 24#include <linux/fs.h>
 25#include <linux/cpu.h>
 26#include <linux/module.h>
 27#include <linux/personality.h>
 28#include <linux/ptrace.h>
 29#include <linux/reboot.h>
 30#include <linux/sched.h>
 31#include <linux/sched/debug.h>
 32#include <linux/sched/task.h>
 33#include <linux/sched/task_stack.h>
 34#include <linux/slab.h>
 35#include <linux/stddef.h>
 36#include <linux/unistd.h>
 37#include <linux/kallsyms.h>
 38#include <linux/uaccess.h>
 39#include <linux/rcupdate.h>
 40#include <linux/random.h>
 41#include <linux/nmi.h>
 42#include <linux/sched/hotplug.h>
 43
 44#include <asm/io.h>
 45#include <asm/asm-offsets.h>
 46#include <asm/assembly.h>
 47#include <asm/pdc.h>
 48#include <asm/pdc_chassis.h>
 49#include <asm/unwind.h>
 50#include <asm/sections.h>
 51#include <asm/cacheflush.h>
 52
 53#define COMMAND_GLOBAL  F_EXTEND(0xfffe0030)
 54#define CMD_RESET       5       /* reset any module */
 55
 56/*
 57** The Wright Brothers and Gecko systems have a H/W problem
 58** (Lasi...'nuf said) may cause a broadcast reset to lockup
 59** the system. An HVERSION dependent PDC call was developed
 60** to perform a "safe", platform specific broadcast reset instead
 61** of kludging up all the code.
 62**
 63** Older machines which do not implement PDC_BROADCAST_RESET will
 64** return (with an error) and the regular broadcast reset can be
 65** issued. Obviously, if the PDC does implement PDC_BROADCAST_RESET
 66** the PDC call will not return (the system will be reset).
 67*/
 68void machine_restart(char *cmd)
 69{
 70#ifdef FASTBOOT_SELFTEST_SUPPORT
 71	/*
 72	 ** If user has modified the Firmware Selftest Bitmap,
 73	 ** run the tests specified in the bitmap after the
 74	 ** system is rebooted w/PDC_DO_RESET.
 75	 **
 76	 ** ftc_bitmap = 0x1AUL "Skip destructive memory tests"
 77	 **
 78	 ** Using "directed resets" at each processor with the MEM_TOC
 79	 ** vector cleared will also avoid running destructive
 80	 ** memory self tests. (Not implemented yet)
 81	 */
 82	if (ftc_bitmap) {
 83		pdc_do_firm_test_reset(ftc_bitmap);
 84	}
 85#endif
 86	/* set up a new led state on systems shipped with a LED State panel */
 87	pdc_chassis_send_status(PDC_CHASSIS_DIRECT_SHUTDOWN);
 88
 89	/* prevent interrupts during reboot */
 90	set_eiem(0);
 91	
 92	/* "Normal" system reset */
 93	pdc_do_reset();
 94
 95	/* Nope...box should reset with just CMD_RESET now */
 96	gsc_writel(CMD_RESET, COMMAND_GLOBAL);
 97
 98	/* Wait for RESET to lay us to rest. */
 99	while (1) ;
100
101}
102
103/*
104 * This routine is called from sys_reboot to actually turn off the
105 * machine 
106 */
107void machine_power_off(void)
108{
109	/* Put the soft power button back under hardware control.
110	 * If the user had already pressed the power button, the
111	 * following call will immediately power off. */
112	pdc_soft_power_button(0);
113	
114	pdc_chassis_send_status(PDC_CHASSIS_DIRECT_SHUTDOWN);
115
116	/* ipmi_poweroff may have been installed. */
117	do_kernel_power_off();
118		
119	/* It seems we have no way to power the system off via
120	 * software. The user has to press the button himself. */
121
122	printk("Power off or press RETURN to reboot.\n");
123
124	/* prevent soft lockup/stalled CPU messages for endless loop. */
125	rcu_sysrq_start();
126	lockup_detector_soft_poweroff();
127	while (1) {
128		/* reboot if user presses RETURN key */
129		if (pdc_iodc_getc() == 13) {
130			printk("Rebooting...\n");
131			machine_restart(NULL);
132		}
133	}
134}
135
136void (*pm_power_off)(void);
137EXPORT_SYMBOL(pm_power_off);
138
139void machine_halt(void)
140{
141	machine_power_off();
142}
143
144void flush_thread(void)
145{
146	/* Only needs to handle fpu stuff or perf monitors.
147	** REVISIT: several arches implement a "lazy fpu state".
148	*/
149}
150
151/*
152 * Idle thread support
153 *
154 * Detect when running on QEMU with SeaBIOS PDC Firmware and let
155 * QEMU idle the host too.
156 */
157
158int running_on_qemu __ro_after_init;
159EXPORT_SYMBOL(running_on_qemu);
160
161/*
162 * Called from the idle thread for the CPU which has been shutdown.
163 */
164void __noreturn arch_cpu_idle_dead(void)
165{
166#ifdef CONFIG_HOTPLUG_CPU
167	idle_task_exit();
168
169	local_irq_disable();
170
171	/* Tell the core that this CPU is now safe to dispose of. */
172	cpuhp_ap_report_dead();
173
174	/* Ensure that the cache lines are written out. */
175	flush_cache_all_local();
176	flush_tlb_all_local(NULL);
177
178	/* Let PDC firmware put CPU into firmware idle loop. */
179	__pdc_cpu_rendezvous();
180
181	pr_warn("PDC does not provide rendezvous function.\n");
182#endif
183	while (1);
184}
185
186void __cpuidle arch_cpu_idle(void)
187{
188	/* nop on real hardware, qemu will idle sleep. */
189	asm volatile("or %%r10,%%r10,%%r10\n":::);
190}
191
192static int __init parisc_idle_init(void)
193{
194	if (!running_on_qemu)
195		cpu_idle_poll_ctrl(1);
196
197	return 0;
198}
199arch_initcall(parisc_idle_init);
200
201/*
202 * Copy architecture-specific thread state
203 */
204int
205copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
206{
207	u64 clone_flags = args->flags;
208	unsigned long usp = args->stack;
209	unsigned long tls = args->tls;
210	struct pt_regs *cregs = &(p->thread.regs);
211	void *stack = task_stack_page(p);
212	
213	/* We have to use void * instead of a function pointer, because
214	 * function pointers aren't a pointer to the function on 64-bit.
215	 * Make them const so the compiler knows they live in .text */
216	extern void * const ret_from_kernel_thread;
217	extern void * const child_return;
218
219	if (unlikely(args->fn)) {
220		/* kernel thread */
221		memset(cregs, 0, sizeof(struct pt_regs));
222		if (args->idle) /* idle thread */
223			return 0;
224		/* Must exit via ret_from_kernel_thread in order
225		 * to call schedule_tail()
226		 */
227		cregs->ksp = (unsigned long) stack + FRAME_SIZE + PT_SZ_ALGN;
228		cregs->kpc = (unsigned long) &ret_from_kernel_thread;
229		/*
230		 * Copy function and argument to be called from
231		 * ret_from_kernel_thread.
232		 */
233#ifdef CONFIG_64BIT
234		cregs->gr[27] = ((unsigned long *)args->fn)[3];
235		cregs->gr[26] = ((unsigned long *)args->fn)[2];
236#else
237		cregs->gr[26] = (unsigned long) args->fn;
238#endif
239		cregs->gr[25] = (unsigned long) args->fn_arg;
240	} else {
241		/* user thread */
242		/* usp must be word aligned.  This also prevents users from
243		 * passing in the value 1 (which is the signal for a special
244		 * return for a kernel thread) */
245		if (usp) {
246			usp = ALIGN(usp, 4);
247			if (likely(usp))
248				cregs->gr[30] = usp;
249		}
250		cregs->ksp = (unsigned long) stack + FRAME_SIZE;
251		cregs->kpc = (unsigned long) &child_return;
252
253		/* Setup thread TLS area */
254		if (clone_flags & CLONE_SETTLS)
255			cregs->cr27 = tls;
256	}
257
258	return 0;
259}
260
261unsigned long
262__get_wchan(struct task_struct *p)
263{
264	struct unwind_frame_info info;
265	unsigned long ip;
266	int count = 0;
267
268	/*
269	 * These bracket the sleeping functions..
270	 */
271
272	unwind_frame_init_from_blocked_task(&info, p);
273	do {
274		if (unwind_once(&info) < 0)
275			return 0;
276		if (task_is_running(p))
277                        return 0;
278		ip = info.ip;
279		if (!in_sched_functions(ip))
280			return ip;
281	} while (count++ < MAX_UNWIND_ENTRIES);
282	return 0;
283}