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 <stdarg.h>
18
19 #include <linux/errno.h>
20 #include <linux/sched.h>
21 #include <linux/sched/debug.h>
22 #include <linux/sched/task.h>
23 #include <linux/sched/task_stack.h>
24 #include <linux/kernel.h>
25 #include <linux/export.h>
26 #include <linux/mm.h>
27 #include <linux/stddef.h>
28 #include <linux/unistd.h>
29 #include <linux/ptrace.h>
30 #include <linux/slab.h>
31 #include <linux/elfcore.h>
32 #include <linux/interrupt.h>
33 #include <linux/delay.h>
34 #include <linux/init_task.h>
35 #include <linux/mqueue.h>
36 #include <linux/fs.h>
37
38 #include <linux/uaccess.h>
39 #include <asm/pgtable.h>
40 #include <asm/io.h>
41 #include <asm/processor.h>
42 #include <asm/spr_defs.h>
43
44 #include <linux/smp.h>
45
46 /*
47 * Pointer to Current thread info structure.
48 *
49 * Used at user space -> kernel transitions.
50 */
51 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
52
53 void machine_restart(void)
54 {
55 printk(KERN_INFO "*** MACHINE RESTART ***\n");
56 __asm__("l.nop 1");
57 }
58
59 /*
60 * Similar to machine_power_off, but don't shut off power. Add code
61 * here to freeze the system for e.g. post-mortem debug purpose when
62 * possible. This halt has nothing to do with the idle halt.
63 */
64 void machine_halt(void)
65 {
66 printk(KERN_INFO "*** MACHINE HALT ***\n");
67 __asm__("l.nop 1");
68 }
69
70 /* If or when software power-off is implemented, add code here. */
71 void machine_power_off(void)
72 {
73 printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
74 __asm__("l.nop 1");
75 }
76
77 /*
78 * Send the doze signal to the cpu if available.
79 * Make sure, that all interrupts are enabled
80 */
81 void arch_cpu_idle(void)
82 {
83 local_irq_enable();
84 if (mfspr(SPR_UPR) & SPR_UPR_PMP)
85 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
86 }
87
88 void (*pm_power_off) (void) = machine_power_off;
89 EXPORT_SYMBOL(pm_power_off);
90
91 /*
92 * When a process does an "exec", machine state like FPU and debug
93 * registers need to be reset. This is a hook function for that.
94 * Currently we don't have any such state to reset, so this is empty.
95 */
96 void flush_thread(void)
97 {
98 }
99
100 void show_regs(struct pt_regs *regs)
101 {
102 extern void show_registers(struct pt_regs *regs);
103
104 show_regs_print_info(KERN_DEFAULT);
105 /* __PHX__ cleanup this mess */
106 show_registers(regs);
107 }
108
109 void release_thread(struct task_struct *dead_task)
110 {
111 }
112
113 /*
114 * Copy the thread-specific (arch specific) info from the current
115 * process to the new one p
116 */
117 extern asmlinkage void ret_from_fork(void);
118
119 /*
120 * copy_thread
121 * @clone_flags: flags
122 * @usp: user stack pointer or fn for kernel thread
123 * @arg: arg to fn for kernel thread; always NULL for userspace thread
124 * @p: the newly created task
125 * @regs: CPU context to copy for userspace thread; always NULL for kthread
126 *
127 * At the top of a newly initialized kernel stack are two stacked pt_reg
128 * structures. The first (topmost) is the userspace context of the thread.
129 * The second is the kernelspace context of the thread.
130 *
131 * A kernel thread will not be returning to userspace, so the topmost pt_regs
132 * struct can be uninitialized; it _does_ need to exist, though, because
133 * a kernel thread can become a userspace thread by doing a kernel_execve, in
134 * which case the topmost context will be initialized and used for 'returning'
135 * to userspace.
136 *
137 * The second pt_reg struct needs to be initialized to 'return' to
138 * ret_from_fork. A kernel thread will need to set r20 to the address of
139 * a function to call into (with arg in r22); userspace threads need to set
140 * r20 to NULL in which case ret_from_fork will just continue a return to
141 * userspace.
142 *
143 * A kernel thread 'fn' may return; this is effectively what happens when
144 * kernel_execve is called. In that case, the userspace pt_regs must have
145 * been initialized (which kernel_execve takes care of, see start_thread
146 * below); ret_from_fork will then continue its execution causing the
147 * 'kernel thread' to return to userspace as a userspace thread.
148 */
149
150 int
151 copy_thread(unsigned long clone_flags, unsigned long usp,
152 unsigned long arg, struct task_struct *p)
153 {
154 struct pt_regs *userregs;
155 struct pt_regs *kregs;
156 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
157 unsigned long top_of_kernel_stack;
158
159 top_of_kernel_stack = sp;
160
161 /* Locate userspace context on stack... */
162 sp -= STACK_FRAME_OVERHEAD; /* redzone */
163 sp -= sizeof(struct pt_regs);
164 userregs = (struct pt_regs *) sp;
165
166 /* ...and kernel context */
167 sp -= STACK_FRAME_OVERHEAD; /* redzone */
168 sp -= sizeof(struct pt_regs);
169 kregs = (struct pt_regs *)sp;
170
171 if (unlikely(p->flags & PF_KTHREAD)) {
172 memset(kregs, 0, sizeof(struct pt_regs));
173 kregs->gpr[20] = usp; /* fn, kernel thread */
174 kregs->gpr[22] = arg;
175 } else {
176 *userregs = *current_pt_regs();
177
178 if (usp)
179 userregs->sp = usp;
180
181 /*
182 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
183 *
184 * The kernel entry is:
185 * int clone (long flags, void *child_stack, int *parent_tid,
186 * int *child_tid, struct void *tls)
187 *
188 * This makes the source r7 in the kernel registers.
189 */
190 if (clone_flags & CLONE_SETTLS)
191 userregs->gpr[10] = userregs->gpr[7];
192
193 userregs->gpr[11] = 0; /* Result from fork() */
194
195 kregs->gpr[20] = 0; /* Userspace thread */
196 }
197
198 /*
199 * _switch wants the kernel stack page in pt_regs->sp so that it
200 * can restore it to thread_info->ksp... see _switch for details.
201 */
202 kregs->sp = top_of_kernel_stack;
203 kregs->gpr[9] = (unsigned long)ret_from_fork;
204
205 task_thread_info(p)->ksp = (unsigned long)kregs;
206
207 return 0;
208 }
209
210 /*
211 * Set up a thread for executing a new program
212 */
213 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
214 {
215 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
216
217 memset(regs, 0, sizeof(struct pt_regs));
218
219 regs->pc = pc;
220 regs->sr = sr;
221 regs->sp = sp;
222 }
223
224 /* Fill in the fpu structure for a core dump. */
225 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
226 {
227 /* TODO */
228 return 0;
229 }
230
231 extern struct thread_info *_switch(struct thread_info *old_ti,
232 struct thread_info *new_ti);
233 extern int lwa_flag;
234
235 struct task_struct *__switch_to(struct task_struct *old,
236 struct task_struct *new)
237 {
238 struct task_struct *last;
239 struct thread_info *new_ti, *old_ti;
240 unsigned long flags;
241
242 local_irq_save(flags);
243
244 /* current_set is an array of saved current pointers
245 * (one for each cpu). we need them at user->kernel transition,
246 * while we save them at kernel->user transition
247 */
248 new_ti = new->stack;
249 old_ti = old->stack;
250
251 lwa_flag = 0;
252
253 current_thread_info_set[smp_processor_id()] = new_ti;
254 last = (_switch(old_ti, new_ti))->task;
255
256 local_irq_restore(flags);
257
258 return last;
259 }
260
261 /*
262 * Write out registers in core dump format, as defined by the
263 * struct user_regs_struct
264 */
265 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
266 {
267 dest[0] = 0; /* r0 */
268 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
269 dest[32] = regs->pc;
270 dest[33] = regs->sr;
271 dest[34] = 0;
272 dest[35] = 0;
273 }
274
275 unsigned long get_wchan(struct task_struct *p)
276 {
277 /* TODO */
278
279 return 0;
280 }