arch/openrisc/kernel/process.c

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