1 /* 2 * OpenRISC process.c 3 * 4 * Linux architectural port borrowing liberally from similar works of 5 * others. All original copyrights apply as per the original source 6 * declaration. 7 * 8 * Modifications for the OpenRISC architecture: 9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> 10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 11 * 12 * This program is free software; you can redistribute it and/or 13 * modify it under the terms of the GNU General Public License 14 * as published by the Free Software Foundation; either version 15 * 2 of the License, or (at your option) any later version. 16 * 17 * This file handles the architecture-dependent parts of process handling... 18 */ 19 20 #define __KERNEL_SYSCALLS__ 21 #include <stdarg.h> 22 23 #include <linux/errno.h> 24 #include <linux/sched.h> 25 #include <linux/kernel.h> 26 #include <linux/module.h> 27 #include <linux/mm.h> 28 #include <linux/stddef.h> 29 #include <linux/unistd.h> 30 #include <linux/ptrace.h> 31 #include <linux/slab.h> 32 #include <linux/elfcore.h> 33 #include <linux/interrupt.h> 34 #include <linux/delay.h> 35 #include <linux/init_task.h> 36 #include <linux/mqueue.h> 37 #include <linux/fs.h> 38 39 #include <asm/uaccess.h> 40 #include <asm/pgtable.h> 41 #include <asm/io.h> 42 #include <asm/processor.h> 43 #include <asm/spr_defs.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(void) 55 { 56 printk(KERN_INFO "*** MACHINE RESTART ***\n"); 57 __asm__("l.nop 1"); 58 } 59 60 /* 61 * Similar to machine_power_off, but don't shut off power. Add code 62 * here to freeze the system for e.g. post-mortem debug purpose when 63 * possible. This halt has nothing to do with the idle halt. 64 */ 65 void machine_halt(void) 66 { 67 printk(KERN_INFO "*** MACHINE HALT ***\n"); 68 __asm__("l.nop 1"); 69 } 70 71 /* If or when software power-off is implemented, add code here. */ 72 void machine_power_off(void) 73 { 74 printk(KERN_INFO "*** MACHINE POWER OFF ***\n"); 75 __asm__("l.nop 1"); 76 } 77 78 void (*pm_power_off) (void) = machine_power_off; 79 80 /* 81 * When a process does an "exec", machine state like FPU and debug 82 * registers need to be reset. This is a hook function for that. 83 * Currently we don't have any such state to reset, so this is empty. 84 */ 85 void flush_thread(void) 86 { 87 } 88 89 void show_regs(struct pt_regs *regs) 90 { 91 extern void show_registers(struct pt_regs *regs); 92 93 show_regs_print_info(KERN_DEFAULT); 94 /* __PHX__ cleanup this mess */ 95 show_registers(regs); 96 } 97 98 unsigned long thread_saved_pc(struct task_struct *t) 99 { 100 return (unsigned long)user_regs(t->stack)->pc; 101 } 102 103 void release_thread(struct task_struct *dead_task) 104 { 105 } 106 107 /* 108 * Copy the thread-specific (arch specific) info from the current 109 * process to the new one p 110 */ 111 extern asmlinkage void ret_from_fork(void); 112 113 /* 114 * copy_thread 115 * @clone_flags: flags 116 * @usp: user stack pointer or fn for kernel thread 117 * @arg: arg to fn for kernel thread; always NULL for userspace thread 118 * @p: the newly created task 119 * @regs: CPU context to copy for userspace thread; always NULL for kthread 120 * 121 * At the top of a newly initialized kernel stack are two stacked pt_reg 122 * structures. The first (topmost) is the userspace context of the thread. 123 * The second is the kernelspace context of the thread. 124 * 125 * A kernel thread will not be returning to userspace, so the topmost pt_regs 126 * struct can be uninitialized; it _does_ need to exist, though, because 127 * a kernel thread can become a userspace thread by doing a kernel_execve, in 128 * which case the topmost context will be initialized and used for 'returning' 129 * to userspace. 130 * 131 * The second pt_reg struct needs to be initialized to 'return' to 132 * ret_from_fork. A kernel thread will need to set r20 to the address of 133 * a function to call into (with arg in r22); userspace threads need to set 134 * r20 to NULL in which case ret_from_fork will just continue a return to 135 * userspace. 136 * 137 * A kernel thread 'fn' may return; this is effectively what happens when 138 * kernel_execve is called. In that case, the userspace pt_regs must have 139 * been initialized (which kernel_execve takes care of, see start_thread 140 * below); ret_from_fork will then continue its execution causing the 141 * 'kernel thread' to return to userspace as a userspace thread. 142 */ 143 144 int 145 copy_thread(unsigned long clone_flags, unsigned long usp, 146 unsigned long arg, struct task_struct *p) 147 { 148 struct pt_regs *userregs; 149 struct pt_regs *kregs; 150 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE; 151 unsigned long top_of_kernel_stack; 152 153 top_of_kernel_stack = sp; 154 155 p->set_child_tid = p->clear_child_tid = NULL; 156 157 /* Locate userspace context on stack... */ 158 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 159 sp -= sizeof(struct pt_regs); 160 userregs = (struct pt_regs *) sp; 161 162 /* ...and kernel context */ 163 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 164 sp -= sizeof(struct pt_regs); 165 kregs = (struct pt_regs *)sp; 166 167 if (unlikely(p->flags & PF_KTHREAD)) { 168 memset(kregs, 0, sizeof(struct pt_regs)); 169 kregs->gpr[20] = usp; /* fn, kernel thread */ 170 kregs->gpr[22] = arg; 171 } else { 172 *userregs = *current_pt_regs(); 173 174 if (usp) 175 userregs->sp = usp; 176 userregs->gpr[11] = 0; /* Result from fork() */ 177 178 kregs->gpr[20] = 0; /* Userspace thread */ 179 } 180 181 /* 182 * _switch wants the kernel stack page in pt_regs->sp so that it 183 * can restore it to thread_info->ksp... see _switch for details. 184 */ 185 kregs->sp = top_of_kernel_stack; 186 kregs->gpr[9] = (unsigned long)ret_from_fork; 187 188 task_thread_info(p)->ksp = (unsigned long)kregs; 189 190 return 0; 191 } 192 193 /* 194 * Set up a thread for executing a new program 195 */ 196 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 197 { 198 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM; 199 200 memset(regs, 0, sizeof(struct pt_regs)); 201 202 regs->pc = pc; 203 regs->sr = sr; 204 regs->sp = sp; 205 } 206 207 /* Fill in the fpu structure for a core dump. */ 208 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu) 209 { 210 /* TODO */ 211 return 0; 212 } 213 214 extern struct thread_info *_switch(struct thread_info *old_ti, 215 struct thread_info *new_ti); 216 217 struct task_struct *__switch_to(struct task_struct *old, 218 struct task_struct *new) 219 { 220 struct task_struct *last; 221 struct thread_info *new_ti, *old_ti; 222 unsigned long flags; 223 224 local_irq_save(flags); 225 226 /* current_set is an array of saved current pointers 227 * (one for each cpu). we need them at user->kernel transition, 228 * while we save them at kernel->user transition 229 */ 230 new_ti = new->stack; 231 old_ti = old->stack; 232 233 current_thread_info_set[smp_processor_id()] = new_ti; 234 last = (_switch(old_ti, new_ti))->task; 235 236 local_irq_restore(flags); 237 238 return last; 239 } 240 241 /* 242 * Write out registers in core dump format, as defined by the 243 * struct user_regs_struct 244 */ 245 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs) 246 { 247 dest[0] = 0; /* r0 */ 248 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long)); 249 dest[32] = regs->pc; 250 dest[33] = regs->sr; 251 dest[34] = 0; 252 dest[35] = 0; 253 } 254 255 unsigned long get_wchan(struct task_struct *p) 256 { 257 /* TODO */ 258 259 return 0; 260 } 261