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