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 	raw_local_irq_enable();
75 }
76 
77 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
machine_halt(void)78 void machine_halt(void)
79 {
80 	local_irq_enable();
81 	mdelay(8);
82 	local_irq_disable();
83 	prom_halt();
84 	panic("Halt failed!");
85 }
86 
machine_restart(char * cmd)87 void machine_restart(char * cmd)
88 {
89 	char *p;
90 
91 	local_irq_enable();
92 	mdelay(8);
93 	local_irq_disable();
94 
95 	p = strchr (reboot_command, '\n');
96 	if (p) *p = 0;
97 	if (cmd)
98 		prom_reboot(cmd);
99 	if (*reboot_command)
100 		prom_reboot(reboot_command);
101 	prom_feval ("reset");
102 	panic("Reboot failed!");
103 }
104 
machine_power_off(void)105 void machine_power_off(void)
106 {
107 	if (auxio_power_register &&
108 	    (!of_node_is_type(of_console_device, "serial") || scons_pwroff)) {
109 		u8 power_register = sbus_readb(auxio_power_register);
110 		power_register |= AUXIO_POWER_OFF;
111 		sbus_writeb(power_register, auxio_power_register);
112 	}
113 
114 	machine_halt();
115 }
116 
show_regs(struct pt_regs * r)117 void show_regs(struct pt_regs *r)
118 {
119 	struct reg_window32 *rw = (struct reg_window32 *) r->u_regs[14];
120 
121 	show_regs_print_info(KERN_DEFAULT);
122 
123         printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
124 	       r->psr, r->pc, r->npc, r->y, print_tainted());
125 	printk("PC: <%pS>\n", (void *) r->pc);
126 	printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
127 	       r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
128 	       r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
129 	printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
130 	       r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
131 	       r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
132 	printk("RPC: <%pS>\n", (void *) r->u_regs[15]);
133 
134 	printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
135 	       rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
136 	       rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
137 	printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
138 	       rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
139 	       rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
140 }
141 
142 /*
143  * The show_stack() is external API which we do not use ourselves.
144  * The oops is printed in die_if_kernel.
145  */
show_stack(struct task_struct * tsk,unsigned long * _ksp,const char * loglvl)146 void show_stack(struct task_struct *tsk, unsigned long *_ksp, const char *loglvl)
147 {
148 	unsigned long pc, fp;
149 	unsigned long task_base;
150 	struct reg_window32 *rw;
151 	int count = 0;
152 
153 	if (!tsk)
154 		tsk = current;
155 
156 	if (tsk == current && !_ksp)
157 		__asm__ __volatile__("mov	%%fp, %0" : "=r" (_ksp));
158 
159 	task_base = (unsigned long) task_stack_page(tsk);
160 	fp = (unsigned long) _ksp;
161 	do {
162 		/* Bogus frame pointer? */
163 		if (fp < (task_base + sizeof(struct thread_info)) ||
164 		    fp >= (task_base + (PAGE_SIZE << 1)))
165 			break;
166 		rw = (struct reg_window32 *) fp;
167 		pc = rw->ins[7];
168 		printk("%s[%08lx : ", loglvl, pc);
169 		printk("%s%pS ] ", loglvl, (void *) pc);
170 		fp = rw->ins[6];
171 	} while (++count < 16);
172 	printk("%s\n", loglvl);
173 }
174 
175 /*
176  * Free current thread data structures etc..
177  */
exit_thread(struct task_struct * tsk)178 void exit_thread(struct task_struct *tsk)
179 {
180 #ifndef CONFIG_SMP
181 	if (last_task_used_math == tsk) {
182 #else
183 	if (test_tsk_thread_flag(tsk, TIF_USEDFPU)) {
184 #endif
185 		/* Keep process from leaving FPU in a bogon state. */
186 		put_psr(get_psr() | PSR_EF);
187 		fpsave(&tsk->thread.float_regs[0], &tsk->thread.fsr,
188 		       &tsk->thread.fpqueue[0], &tsk->thread.fpqdepth);
189 #ifndef CONFIG_SMP
190 		last_task_used_math = NULL;
191 #else
192 		clear_ti_thread_flag(task_thread_info(tsk), TIF_USEDFPU);
193 #endif
194 	}
195 }
196 
197 void flush_thread(void)
198 {
199 	current_thread_info()->w_saved = 0;
200 
201 #ifndef CONFIG_SMP
202 	if(last_task_used_math == current) {
203 #else
204 	if (test_thread_flag(TIF_USEDFPU)) {
205 #endif
206 		/* Clean the fpu. */
207 		put_psr(get_psr() | PSR_EF);
208 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
209 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
210 #ifndef CONFIG_SMP
211 		last_task_used_math = NULL;
212 #else
213 		clear_thread_flag(TIF_USEDFPU);
214 #endif
215 	}
216 }
217 
218 static inline struct sparc_stackf __user *
219 clone_stackframe(struct sparc_stackf __user *dst,
220 		 struct sparc_stackf __user *src)
221 {
222 	unsigned long size, fp;
223 	struct sparc_stackf *tmp;
224 	struct sparc_stackf __user *sp;
225 
226 	if (get_user(tmp, &src->fp))
227 		return NULL;
228 
229 	fp = (unsigned long) tmp;
230 	size = (fp - ((unsigned long) src));
231 	fp = (unsigned long) dst;
232 	sp = (struct sparc_stackf __user *)(fp - size);
233 
234 	/* do_fork() grabs the parent semaphore, we must release it
235 	 * temporarily so we can build the child clone stack frame
236 	 * without deadlocking.
237 	 */
238 	if (__copy_user(sp, src, size))
239 		sp = NULL;
240 	else if (put_user(fp, &sp->fp))
241 		sp = NULL;
242 
243 	return sp;
244 }
245 
246 /* Copy a Sparc thread.  The fork() return value conventions
247  * under SunOS are nothing short of bletcherous:
248  * Parent -->  %o0 == childs  pid, %o1 == 0
249  * Child  -->  %o0 == parents pid, %o1 == 1
250  *
251  * NOTE: We have a separate fork kpsr/kwim because
252  *       the parent could change these values between
253  *       sys_fork invocation and when we reach here
254  *       if the parent should sleep while trying to
255  *       allocate the task_struct and kernel stack in
256  *       do_fork().
257  * XXX See comment above sys_vfork in sparc64. todo.
258  */
259 extern void ret_from_fork(void);
260 extern void ret_from_kernel_thread(void);
261 
262 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
263 {
264 	unsigned long clone_flags = args->flags;
265 	unsigned long sp = args->stack;
266 	unsigned long tls = args->tls;
267 	struct thread_info *ti = task_thread_info(p);
268 	struct pt_regs *childregs, *regs = current_pt_regs();
269 	char *new_stack;
270 
271 #ifndef CONFIG_SMP
272 	if(last_task_used_math == current) {
273 #else
274 	if (test_thread_flag(TIF_USEDFPU)) {
275 #endif
276 		put_psr(get_psr() | PSR_EF);
277 		fpsave(&p->thread.float_regs[0], &p->thread.fsr,
278 		       &p->thread.fpqueue[0], &p->thread.fpqdepth);
279 	}
280 
281 	/*
282 	 *  p->thread_info         new_stack   childregs stack bottom
283 	 *  !                      !           !             !
284 	 *  V                      V (stk.fr.) V  (pt_regs)  V
285 	 *  +----- - - - - - ------+===========+=============+
286 	 */
287 	new_stack = task_stack_page(p) + THREAD_SIZE;
288 	new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
289 	childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);
290 
291 	/*
292 	 * A new process must start with interrupts disabled, see schedule_tail()
293 	 * and finish_task_switch(). (If we do not do it and if a timer interrupt
294 	 * hits before we unlock and attempts to take the rq->lock, we deadlock.)
295 	 *
296 	 * Thus, kpsr |= PSR_PIL.
297 	 */
298 	ti->ksp = (unsigned long) new_stack;
299 	p->thread.kregs = childregs;
300 
301 	if (unlikely(args->fn)) {
302 		extern int nwindows;
303 		unsigned long psr;
304 		memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
305 		ti->kpc = (((unsigned long) ret_from_kernel_thread) - 0x8);
306 		childregs->u_regs[UREG_G1] = (unsigned long) args->fn;
307 		childregs->u_regs[UREG_G2] = (unsigned long) args->fn_arg;
308 		psr = childregs->psr = get_psr();
309 		ti->kpsr = psr | PSR_PIL;
310 		ti->kwim = 1 << (((psr & PSR_CWP) + 1) % nwindows);
311 		return 0;
312 	}
313 	memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
314 	childregs->u_regs[UREG_FP] = sp;
315 	ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
316 	ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
317 	ti->kwim = current->thread.fork_kwim;
318 
319 	if (sp != regs->u_regs[UREG_FP]) {
320 		struct sparc_stackf __user *childstack;
321 		struct sparc_stackf __user *parentstack;
322 
323 		/*
324 		 * This is a clone() call with supplied user stack.
325 		 * Set some valid stack frames to give to the child.
326 		 */
327 		childstack = (struct sparc_stackf __user *)
328 			(sp & ~0xfUL);
329 		parentstack = (struct sparc_stackf __user *)
330 			regs->u_regs[UREG_FP];
331 
332 #if 0
333 		printk("clone: parent stack:\n");
334 		show_stackframe(parentstack);
335 #endif
336 
337 		childstack = clone_stackframe(childstack, parentstack);
338 		if (!childstack)
339 			return -EFAULT;
340 
341 #if 0
342 		printk("clone: child stack:\n");
343 		show_stackframe(childstack);
344 #endif
345 
346 		childregs->u_regs[UREG_FP] = (unsigned long)childstack;
347 	}
348 
349 #ifdef CONFIG_SMP
350 	/* FPU must be disabled on SMP. */
351 	childregs->psr &= ~PSR_EF;
352 	clear_tsk_thread_flag(p, TIF_USEDFPU);
353 #endif
354 
355 	/* Set the return value for the child. */
356 	childregs->u_regs[UREG_I0] = current->pid;
357 	childregs->u_regs[UREG_I1] = 1;
358 
359 	/* Set the return value for the parent. */
360 	regs->u_regs[UREG_I1] = 0;
361 
362 	if (clone_flags & CLONE_SETTLS)
363 		childregs->u_regs[UREG_G7] = tls;
364 
365 	return 0;
366 }
367 
368 unsigned long __get_wchan(struct task_struct *task)
369 {
370 	unsigned long pc, fp, bias = 0;
371 	unsigned long task_base = (unsigned long) task;
372         unsigned long ret = 0;
373 	struct reg_window32 *rw;
374 	int count = 0;
375 
376 	fp = task_thread_info(task)->ksp + bias;
377 	do {
378 		/* Bogus frame pointer? */
379 		if (fp < (task_base + sizeof(struct thread_info)) ||
380 		    fp >= (task_base + (2 * PAGE_SIZE)))
381 			break;
382 		rw = (struct reg_window32 *) fp;
383 		pc = rw->ins[7];
384 		if (!in_sched_functions(pc)) {
385 			ret = pc;
386 			goto out;
387 		}
388 		fp = rw->ins[6] + bias;
389 	} while (++count < 16);
390 
391 out:
392 	return ret;
393 }
394 
395