1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * OpenRISC process.c
4 *
5 * Linux architectural port borrowing liberally from similar works of
6 * others. All original copyrights apply as per the original source
7 * declaration.
8 *
9 * Modifications for the OpenRISC architecture:
10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
11 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
12 *
13 * This file handles the architecture-dependent parts of process handling...
14 */
15
16 #define __KERNEL_SYSCALLS__
17 #include <linux/cpu.h>
18 #include <linux/errno.h>
19 #include <linux/sched.h>
20 #include <linux/sched/debug.h>
21 #include <linux/sched/task.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/kernel.h>
24 #include <linux/export.h>
25 #include <linux/mm.h>
26 #include <linux/stddef.h>
27 #include <linux/unistd.h>
28 #include <linux/ptrace.h>
29 #include <linux/slab.h>
30 #include <linux/elfcore.h>
31 #include <linux/interrupt.h>
32 #include <linux/delay.h>
33 #include <linux/init_task.h>
34 #include <linux/mqueue.h>
35 #include <linux/fs.h>
36 #include <linux/reboot.h>
37
38 #include <linux/uaccess.h>
39 #include <asm/fpu.h>
40 #include <asm/io.h>
41 #include <asm/processor.h>
42 #include <asm/spr_defs.h>
43 #include <asm/switch_to.h>
44
45 #include <linux/smp.h>
46
47 /*
48 * Pointer to Current thread info structure.
49 *
50 * Used at user space -> kernel transitions.
51 */
52 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
53
54 void machine_restart(char *cmd)
55 {
56 do_kernel_restart(cmd);
57
58 __asm__("l.nop 13");
59
60 /* Give a grace period for failure to restart of 1s */
61 mdelay(1000);
62
63 /* Whoops - the platform was unable to reboot. Tell the user! */
64 pr_emerg("Reboot failed -- System halted\n");
65 while (1);
66 }
67
68 /*
69 * This is used if a sys-off handler was not set by a power management
70 * driver, in this case we can assume we are on a simulator. On
71 * OpenRISC simulators l.nop 1 will trigger the simulator exit.
72 */
73 static void default_power_off(void)
74 {
75 __asm__("l.nop 1");
76 }
77
78 /*
79 * Similar to machine_power_off, but don't shut off power. Add code
80 * here to freeze the system for e.g. post-mortem debug purpose when
81 * possible. This halt has nothing to do with the idle halt.
82 */
83 void machine_halt(void)
84 {
85 printk(KERN_INFO "*** MACHINE HALT ***\n");
86 __asm__("l.nop 1");
87 }
88
89 /* If or when software power-off is implemented, add code here. */
90 void machine_power_off(void)
91 {
92 printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
93 do_kernel_power_off();
94 default_power_off();
95 }
96
97 /*
98 * Send the doze signal to the cpu if available.
99 * Make sure, that all interrupts are enabled
100 */
101 void arch_cpu_idle(void)
102 {
103 raw_local_irq_enable();
104 if (mfspr(SPR_UPR) & SPR_UPR_PMP)
105 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
106 raw_local_irq_disable();
107 }
108
109 void (*pm_power_off)(void) = NULL;
110 EXPORT_SYMBOL(pm_power_off);
111
112 /*
113 * When a process does an "exec", machine state like FPU and debug
114 * registers need to be reset. This is a hook function for that.
115 * Currently we don't have any such state to reset, so this is empty.
116 */
117 void flush_thread(void)
118 {
119 }
120
121 void show_regs(struct pt_regs *regs)
122 {
123 show_regs_print_info(KERN_DEFAULT);
124 /* __PHX__ cleanup this mess */
125 show_registers(regs);
126 }
127
128 /*
129 * Copy the thread-specific (arch specific) info from the current
130 * process to the new one p
131 */
132 extern asmlinkage void ret_from_fork(void);
133
134 /*
135 * copy_thread
136 * @clone_flags: flags
137 * @usp: user stack pointer or fn for kernel thread
138 * @arg: arg to fn for kernel thread; always NULL for userspace thread
139 * @p: the newly created task
140 * @tls: the Thread Local Storage pointer for the new process
141 *
142 * At the top of a newly initialized kernel stack are two stacked pt_reg
143 * structures. The first (topmost) is the userspace context of the thread.
144 * The second is the kernelspace context of the thread.
145 *
146 * A kernel thread will not be returning to userspace, so the topmost pt_regs
147 * struct can be uninitialized; it _does_ need to exist, though, because
148 * a kernel thread can become a userspace thread by doing a kernel_execve, in
149 * which case the topmost context will be initialized and used for 'returning'
150 * to userspace.
151 *
152 * The second pt_reg struct needs to be initialized to 'return' to
153 * ret_from_fork. A kernel thread will need to set r20 to the address of
154 * a function to call into (with arg in r22); userspace threads need to set
155 * r20 to NULL in which case ret_from_fork will just continue a return to
156 * userspace.
157 *
158 * A kernel thread 'fn' may return; this is effectively what happens when
159 * kernel_execve is called. In that case, the userspace pt_regs must have
160 * been initialized (which kernel_execve takes care of, see start_thread
161 * below); ret_from_fork will then continue its execution causing the
162 * 'kernel thread' to return to userspace as a userspace thread.
163 */
164
165 int
166 copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
167 {
168 unsigned long clone_flags = args->flags;
169 unsigned long usp = args->stack;
170 unsigned long tls = args->tls;
171 struct pt_regs *userregs;
172 struct pt_regs *kregs;
173 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
174 unsigned long top_of_kernel_stack;
175
176 top_of_kernel_stack = sp;
177
178 /* Locate userspace context on stack... */
179 sp -= STACK_FRAME_OVERHEAD; /* redzone */
180 sp -= sizeof(struct pt_regs);
181 userregs = (struct pt_regs *) sp;
182
183 /* ...and kernel context */
184 sp -= STACK_FRAME_OVERHEAD; /* redzone */
185 sp -= sizeof(struct pt_regs);
186 kregs = (struct pt_regs *)sp;
187
188 if (unlikely(args->fn)) {
189 memset(kregs, 0, sizeof(struct pt_regs));
190 kregs->gpr[20] = (unsigned long)args->fn;
191 kregs->gpr[22] = (unsigned long)args->fn_arg;
192 } else {
193 *userregs = *current_pt_regs();
194
195 if (usp)
196 userregs->sp = usp;
197
198 /*
199 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer.
200 */
201 if (clone_flags & CLONE_SETTLS)
202 userregs->gpr[10] = tls;
203
204 userregs->gpr[11] = 0; /* Result from fork() */
205
206 kregs->gpr[20] = 0; /* Userspace thread */
207 }
208
209 /*
210 * _switch wants the kernel stack page in pt_regs->sp so that it
211 * can restore it to thread_info->ksp... see _switch for details.
212 */
213 kregs->sp = top_of_kernel_stack;
214 kregs->gpr[9] = (unsigned long)ret_from_fork;
215
216 task_thread_info(p)->ksp = (unsigned long)kregs;
217
218 return 0;
219 }
220
221 /*
222 * Set up a thread for executing a new program
223 */
224 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
225 {
226 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
227
228 memset(regs, 0, sizeof(struct pt_regs));
229
230 regs->pc = pc;
231 regs->sr = sr;
232 regs->sp = sp;
233 }
234
235 extern struct thread_info *_switch(struct thread_info *old_ti,
236 struct thread_info *new_ti);
237 extern int lwa_flag;
238
239 struct task_struct *__switch_to(struct task_struct *old,
240 struct task_struct *new)
241 {
242 struct task_struct *last;
243 struct thread_info *new_ti, *old_ti;
244 unsigned long flags;
245
246 local_irq_save(flags);
247
248 save_fpu(current);
249
250 /* current_set is an array of saved current pointers
251 * (one for each cpu). we need them at user->kernel transition,
252 * while we save them at kernel->user transition
253 */
254 new_ti = new->stack;
255 old_ti = old->stack;
256
257 lwa_flag = 0;
258
259 current_thread_info_set[smp_processor_id()] = new_ti;
260 last = (_switch(old_ti, new_ti))->task;
261
262 restore_fpu(current);
263
264 local_irq_restore(flags);
265
266 return last;
267 }
268
269 /*
270 * Write out registers in core dump format, as defined by the
271 * struct user_regs_struct
272 */
273 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
274 {
275 dest[0] = 0; /* r0 */
276 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
277 dest[32] = regs->pc;
278 dest[33] = regs->sr;
279 dest[34] = 0;
280 dest[35] = 0;
281 }
282
283 unsigned long __get_wchan(struct task_struct *p)
284 {
285 /* TODO */
286
287 return 0;
288 }
289
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