1 // SPDX-License-Identifier: GPL-2.0
2 /*  linux/arch/sparc/kernel/process.c
3  *
4  *  Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
5  *  Copyright (C) 1996 Eddie C. Dost   (ecd@skynet.be)
6  */
7 
8 /*
9  * This file handles the architecture-dependent parts of process handling..
10  */
11 #include <linux/elfcore.h>
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/stddef.h>
21 #include <linux/ptrace.h>
22 #include <linux/user.h>
23 #include <linux/smp.h>
24 #include <linux/reboot.h>
25 #include <linux/delay.h>
26 #include <linux/pm.h>
27 #include <linux/slab.h>
28 #include <linux/cpu.h>
29 
30 #include <asm/auxio.h>
31 #include <asm/oplib.h>
32 #include <linux/uaccess.h>
33 #include <asm/page.h>
34 #include <asm/delay.h>
35 #include <asm/processor.h>
36 #include <asm/psr.h>
37 #include <asm/elf.h>
38 #include <asm/prom.h>
39 #include <asm/unistd.h>
40 #include <asm/setup.h>
41 
42 #include "kernel.h"
43 
44 /*
45  * Power management idle function
46  * Set in pm platform drivers (apc.c and pmc.c)
47  */
48 void (*sparc_idle)(void);
49 
50 /*
51  * Power-off handler instantiation for pm.h compliance
52  * This is done via auxio, but could be used as a fallback
53  * handler when auxio is not present-- unused for now...
54  */
55 void (*pm_power_off)(void) = machine_power_off;
56 EXPORT_SYMBOL(pm_power_off);
57 
58 /*
59  * sysctl - toggle power-off restriction for serial console
60  * systems in machine_power_off()
61  */
62 int scons_pwroff = 1;
63 
64 extern void fpsave(unsigned long *, unsigned long *, void *, unsigned long *);
65 
66 struct task_struct *last_task_used_math = NULL;
67 struct thread_info *current_set[NR_CPUS];
68 
69 /* Idle loop support. */
arch_cpu_idle(void)70 void arch_cpu_idle(void)
71 {
72 	if (sparc_idle)
73 		(*sparc_idle)();
74 }
75 
76 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
machine_halt(void)77 void machine_halt(void)
78 {
79 	local_irq_enable();
80 	mdelay(8);
81 	local_irq_disable();
82 	prom_halt();
83 	panic("Halt failed!");
84 }
85 
machine_restart(char * cmd)86 void machine_restart(char * cmd)
87 {
88 	char *p;
89 
90 	local_irq_enable();
91 	mdelay(8);
92 	local_irq_disable();
93 
94 	p = strchr (reboot_command, '\n');
95 	if (p) *p = 0;
96 	if (cmd)
97 		prom_reboot(cmd);
98 	if (*reboot_command)
99 		prom_reboot(reboot_command);
100 	prom_feval ("reset");
101 	panic("Reboot failed!");
102 }
103 
machine_power_off(void)104 void machine_power_off(void)
105 {
106 	if (auxio_power_register &&
107 	    (!of_node_is_type(of_console_device, "serial") || scons_pwroff)) {
108 		u8 power_register = sbus_readb(auxio_power_register);
109 		power_register |= AUXIO_POWER_OFF;
110 		sbus_writeb(power_register, auxio_power_register);
111 	}
112 
113 	machine_halt();
114 }
115 
show_regs(struct pt_regs * r)116 void show_regs(struct pt_regs *r)
117 {
118 	struct reg_window32 *rw = (struct reg_window32 *) r->u_regs[14];
119 
120 	show_regs_print_info(KERN_DEFAULT);
121 
122         printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
123 	       r->psr, r->pc, r->npc, r->y, print_tainted());
124 	printk("PC: <%pS>\n", (void *) r->pc);
125 	printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
126 	       r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
127 	       r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
128 	printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
129 	       r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
130 	       r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
131 	printk("RPC: <%pS>\n", (void *) r->u_regs[15]);
132 
133 	printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
134 	       rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
135 	       rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
136 	printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
137 	       rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
138 	       rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
139 }
140 
141 /*
142  * The show_stack() is external API which we do not use ourselves.
143  * The oops is printed in die_if_kernel.
144  */
show_stack(struct task_struct * tsk,unsigned long * _ksp,const char * loglvl)145 void show_stack(struct task_struct *tsk, unsigned long *_ksp, const char *loglvl)
146 {
147 	unsigned long pc, fp;
148 	unsigned long task_base;
149 	struct reg_window32 *rw;
150 	int count = 0;
151 
152 	if (!tsk)
153 		tsk = current;
154 
155 	if (tsk == current && !_ksp)
156 		__asm__ __volatile__("mov	%%fp, %0" : "=r" (_ksp));
157 
158 	task_base = (unsigned long) task_stack_page(tsk);
159 	fp = (unsigned long) _ksp;
160 	do {
161 		/* Bogus frame pointer? */
162 		if (fp < (task_base + sizeof(struct thread_info)) ||
163 		    fp >= (task_base + (PAGE_SIZE << 1)))
164 			break;
165 		rw = (struct reg_window32 *) fp;
166 		pc = rw->ins[7];
167 		printk("%s[%08lx : ", loglvl, pc);
168 		printk("%s%pS ] ", loglvl, (void *) pc);
169 		fp = rw->ins[6];
170 	} while (++count < 16);
171 	printk("%s\n", loglvl);
172 }
173 
174 /*
175  * Free current thread data structures etc..
176  */
exit_thread(struct task_struct * tsk)177 void exit_thread(struct task_struct *tsk)
178 {
179 #ifndef CONFIG_SMP
180 	if (last_task_used_math == tsk) {
181 #else
182 	if (test_tsk_thread_flag(tsk, TIF_USEDFPU)) {
183 #endif
184 		/* Keep process from leaving FPU in a bogon state. */
185 		put_psr(get_psr() | PSR_EF);
186 		fpsave(&tsk->thread.float_regs[0], &tsk->thread.fsr,
187 		       &tsk->thread.fpqueue[0], &tsk->thread.fpqdepth);
188 #ifndef CONFIG_SMP
189 		last_task_used_math = NULL;
190 #else
191 		clear_ti_thread_flag(task_thread_info(tsk), TIF_USEDFPU);
192 #endif
193 	}
194 }
195 
196 void flush_thread(void)
197 {
198 	current_thread_info()->w_saved = 0;
199 
200 #ifndef CONFIG_SMP
201 	if(last_task_used_math == current) {
202 #else
203 	if (test_thread_flag(TIF_USEDFPU)) {
204 #endif
205 		/* Clean the fpu. */
206 		put_psr(get_psr() | PSR_EF);
207 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
208 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
209 #ifndef CONFIG_SMP
210 		last_task_used_math = NULL;
211 #else
212 		clear_thread_flag(TIF_USEDFPU);
213 #endif
214 	}
215 }
216 
217 static inline struct sparc_stackf __user *
218 clone_stackframe(struct sparc_stackf __user *dst,
219 		 struct sparc_stackf __user *src)
220 {
221 	unsigned long size, fp;
222 	struct sparc_stackf *tmp;
223 	struct sparc_stackf __user *sp;
224 
225 	if (get_user(tmp, &src->fp))
226 		return NULL;
227 
228 	fp = (unsigned long) tmp;
229 	size = (fp - ((unsigned long) src));
230 	fp = (unsigned long) dst;
231 	sp = (struct sparc_stackf __user *)(fp - size);
232 
233 	/* do_fork() grabs the parent semaphore, we must release it
234 	 * temporarily so we can build the child clone stack frame
235 	 * without deadlocking.
236 	 */
237 	if (__copy_user(sp, src, size))
238 		sp = NULL;
239 	else if (put_user(fp, &sp->fp))
240 		sp = NULL;
241 
242 	return sp;
243 }
244 
245 /* Copy a Sparc thread.  The fork() return value conventions
246  * under SunOS are nothing short of bletcherous:
247  * Parent -->  %o0 == childs  pid, %o1 == 0
248  * Child  -->  %o0 == parents pid, %o1 == 1
249  *
250  * NOTE: We have a separate fork kpsr/kwim because
251  *       the parent could change these values between
252  *       sys_fork invocation and when we reach here
253  *       if the parent should sleep while trying to
254  *       allocate the task_struct and kernel stack in
255  *       do_fork().
256  * XXX See comment above sys_vfork in sparc64. todo.
257  */
258 extern void ret_from_fork(void);
259 extern void ret_from_kernel_thread(void);
260 
261 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
262 {
263 	unsigned long clone_flags = args->flags;
264 	unsigned long sp = args->stack;
265 	unsigned long tls = args->tls;
266 	struct thread_info *ti = task_thread_info(p);
267 	struct pt_regs *childregs, *regs = current_pt_regs();
268 	char *new_stack;
269 
270 #ifndef CONFIG_SMP
271 	if(last_task_used_math == current) {
272 #else
273 	if (test_thread_flag(TIF_USEDFPU)) {
274 #endif
275 		put_psr(get_psr() | PSR_EF);
276 		fpsave(&p->thread.float_regs[0], &p->thread.fsr,
277 		       &p->thread.fpqueue[0], &p->thread.fpqdepth);
278 	}
279 
280 	/*
281 	 *  p->thread_info         new_stack   childregs stack bottom
282 	 *  !                      !           !             !
283 	 *  V                      V (stk.fr.) V  (pt_regs)  V
284 	 *  +----- - - - - - ------+===========+=============+
285 	 */
286 	new_stack = task_stack_page(p) + THREAD_SIZE;
287 	new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
288 	childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);
289 
290 	/*
291 	 * A new process must start with interrupts disabled, see schedule_tail()
292 	 * and finish_task_switch(). (If we do not do it and if a timer interrupt
293 	 * hits before we unlock and attempts to take the rq->lock, we deadlock.)
294 	 *
295 	 * Thus, kpsr |= PSR_PIL.
296 	 */
297 	ti->ksp = (unsigned long) new_stack;
298 	p->thread.kregs = childregs;
299 
300 	if (unlikely(args->fn)) {
301 		extern int nwindows;
302 		unsigned long psr;
303 		memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
304 		ti->kpc = (((unsigned long) ret_from_kernel_thread) - 0x8);
305 		childregs->u_regs[UREG_G1] = (unsigned long) args->fn;
306 		childregs->u_regs[UREG_G2] = (unsigned long) args->fn_arg;
307 		psr = childregs->psr = get_psr();
308 		ti->kpsr = psr | PSR_PIL;
309 		ti->kwim = 1 << (((psr & PSR_CWP) + 1) % nwindows);
310 		return 0;
311 	}
312 	memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
313 	childregs->u_regs[UREG_FP] = sp;
314 	ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
315 	ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
316 	ti->kwim = current->thread.fork_kwim;
317 
318 	if (sp != regs->u_regs[UREG_FP]) {
319 		struct sparc_stackf __user *childstack;
320 		struct sparc_stackf __user *parentstack;
321 
322 		/*
323 		 * This is a clone() call with supplied user stack.
324 		 * Set some valid stack frames to give to the child.
325 		 */
326 		childstack = (struct sparc_stackf __user *)
327 			(sp & ~0xfUL);
328 		parentstack = (struct sparc_stackf __user *)
329 			regs->u_regs[UREG_FP];
330 
331 #if 0
332 		printk("clone: parent stack:\n");
333 		show_stackframe(parentstack);
334 #endif
335 
336 		childstack = clone_stackframe(childstack, parentstack);
337 		if (!childstack)
338 			return -EFAULT;
339 
340 #if 0
341 		printk("clone: child stack:\n");
342 		show_stackframe(childstack);
343 #endif
344 
345 		childregs->u_regs[UREG_FP] = (unsigned long)childstack;
346 	}
347 
348 #ifdef CONFIG_SMP
349 	/* FPU must be disabled on SMP. */
350 	childregs->psr &= ~PSR_EF;
351 	clear_tsk_thread_flag(p, TIF_USEDFPU);
352 #endif
353 
354 	/* Set the return value for the child. */
355 	childregs->u_regs[UREG_I0] = current->pid;
356 	childregs->u_regs[UREG_I1] = 1;
357 
358 	/* Set the return value for the parent. */
359 	regs->u_regs[UREG_I1] = 0;
360 
361 	if (clone_flags & CLONE_SETTLS)
362 		childregs->u_regs[UREG_G7] = tls;
363 
364 	return 0;
365 }
366 
367 unsigned long __get_wchan(struct task_struct *task)
368 {
369 	unsigned long pc, fp, bias = 0;
370 	unsigned long task_base = (unsigned long) task;
371         unsigned long ret = 0;
372 	struct reg_window32 *rw;
373 	int count = 0;
374 
375 	fp = task_thread_info(task)->ksp + bias;
376 	do {
377 		/* Bogus frame pointer? */
378 		if (fp < (task_base + sizeof(struct thread_info)) ||
379 		    fp >= (task_base + (2 * PAGE_SIZE)))
380 			break;
381 		rw = (struct reg_window32 *) fp;
382 		pc = rw->ins[7];
383 		if (!in_sched_functions(pc)) {
384 			ret = pc;
385 			goto out;
386 		}
387 		fp = rw->ins[6] + bias;
388 	} while (++count < 16);
389 
390 out:
391 	return ret;
392 }
393 
394