1 // SPDX-License-Identifier: GPL-2.0-or-later
5 * Linux architectural port borrowing liberally from similar works of
6 * others. All original copyrights apply as per the original source
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>
13 * This file handles the architecture-dependent parts of process handling...
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>
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>
35 #include <linux/reboot.h>
37 #include <linux/uaccess.h>
39 #include <asm/processor.h>
40 #include <asm/spr_defs.h>
42 #include <linux/smp.h>
45 * Pointer to Current thread info structure.
47 * Used at user space -> kernel transitions.
49 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
51 void machine_restart(char *cmd)
53 do_kernel_restart(cmd);
55 /* Give a grace period for failure to restart of 1s */
58 /* Whoops - the platform was unable to reboot. Tell the user! */
59 pr_emerg("Reboot failed -- System halted\n");
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.
68 void machine_halt(void)
70 printk(KERN_INFO "*** MACHINE HALT ***\n");
74 /* If or when software power-off is implemented, add code here. */
75 void machine_power_off(void)
77 printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
82 * Send the doze signal to the cpu if available.
83 * Make sure, that all interrupts are enabled
85 void arch_cpu_idle(void)
87 raw_local_irq_enable();
88 if (mfspr(SPR_UPR) & SPR_UPR_PMP)
89 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
92 void (*pm_power_off) (void) = machine_power_off;
93 EXPORT_SYMBOL(pm_power_off);
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.
100 void flush_thread(void)
104 void show_regs(struct pt_regs *regs)
106 extern void show_registers(struct pt_regs *regs);
108 show_regs_print_info(KERN_DEFAULT);
109 /* __PHX__ cleanup this mess */
110 show_registers(regs);
113 void release_thread(struct task_struct *dead_task)
118 * Copy the thread-specific (arch specific) info from the current
119 * process to the new one p
121 extern asmlinkage void ret_from_fork(void);
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
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.
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'
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
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.
155 copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
157 unsigned long clone_flags = args->flags;
158 unsigned long usp = args->stack;
159 unsigned long tls = args->tls;
160 struct pt_regs *userregs;
161 struct pt_regs *kregs;
162 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
163 unsigned long top_of_kernel_stack;
165 top_of_kernel_stack = sp;
167 /* Locate userspace context on stack... */
168 sp -= STACK_FRAME_OVERHEAD; /* redzone */
169 sp -= sizeof(struct pt_regs);
170 userregs = (struct pt_regs *) sp;
172 /* ...and kernel context */
173 sp -= STACK_FRAME_OVERHEAD; /* redzone */
174 sp -= sizeof(struct pt_regs);
175 kregs = (struct pt_regs *)sp;
177 if (unlikely(args->fn)) {
178 memset(kregs, 0, sizeof(struct pt_regs));
179 kregs->gpr[20] = (unsigned long)args->fn;
180 kregs->gpr[22] = (unsigned long)args->fn_arg;
182 *userregs = *current_pt_regs();
188 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer.
190 if (clone_flags & CLONE_SETTLS)
191 userregs->gpr[10] = tls;
193 userregs->gpr[11] = 0; /* Result from fork() */
195 kregs->gpr[20] = 0; /* Userspace thread */
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.
202 kregs->sp = top_of_kernel_stack;
203 kregs->gpr[9] = (unsigned long)ret_from_fork;
205 task_thread_info(p)->ksp = (unsigned long)kregs;
211 * Set up a thread for executing a new program
213 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
215 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
217 memset(regs, 0, sizeof(struct pt_regs));
224 extern struct thread_info *_switch(struct thread_info *old_ti,
225 struct thread_info *new_ti);
228 struct task_struct *__switch_to(struct task_struct *old,
229 struct task_struct *new)
231 struct task_struct *last;
232 struct thread_info *new_ti, *old_ti;
235 local_irq_save(flags);
237 /* current_set is an array of saved current pointers
238 * (one for each cpu). we need them at user->kernel transition,
239 * while we save them at kernel->user transition
246 current_thread_info_set[smp_processor_id()] = new_ti;
247 last = (_switch(old_ti, new_ti))->task;
249 local_irq_restore(flags);
255 * Write out registers in core dump format, as defined by the
256 * struct user_regs_struct
258 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
260 dest[0] = 0; /* r0 */
261 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
268 unsigned long __get_wchan(struct task_struct *p)