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 <linux/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; 176 177 /* 178 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone. 179 * 180 * The kernel entry is: 181 * int clone (long flags, void *child_stack, int *parent_tid, 182 * int *child_tid, struct void *tls) 183 * 184 * This makes the source r7 in the kernel registers. 185 */ 186 if (clone_flags & CLONE_SETTLS) 187 userregs->gpr[10] = userregs->gpr[7]; 188 189 userregs->gpr[11] = 0; /* Result from fork() */ 190 191 kregs->gpr[20] = 0; /* Userspace thread */ 192 } 193 194 /* 195 * _switch wants the kernel stack page in pt_regs->sp so that it 196 * can restore it to thread_info->ksp... see _switch for details. 197 */ 198 kregs->sp = top_of_kernel_stack; 199 kregs->gpr[9] = (unsigned long)ret_from_fork; 200 201 task_thread_info(p)->ksp = (unsigned long)kregs; 202 203 return 0; 204 } 205 206 /* 207 * Set up a thread for executing a new program 208 */ 209 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 210 { 211 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM; 212 213 memset(regs, 0, sizeof(struct pt_regs)); 214 215 regs->pc = pc; 216 regs->sr = sr; 217 regs->sp = sp; 218 } 219 220 /* Fill in the fpu structure for a core dump. */ 221 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu) 222 { 223 /* TODO */ 224 return 0; 225 } 226 227 extern struct thread_info *_switch(struct thread_info *old_ti, 228 struct thread_info *new_ti); 229 230 struct task_struct *__switch_to(struct task_struct *old, 231 struct task_struct *new) 232 { 233 struct task_struct *last; 234 struct thread_info *new_ti, *old_ti; 235 unsigned long flags; 236 237 local_irq_save(flags); 238 239 /* current_set is an array of saved current pointers 240 * (one for each cpu). we need them at user->kernel transition, 241 * while we save them at kernel->user transition 242 */ 243 new_ti = new->stack; 244 old_ti = old->stack; 245 246 current_thread_info_set[smp_processor_id()] = new_ti; 247 last = (_switch(old_ti, new_ti))->task; 248 249 local_irq_restore(flags); 250 251 return last; 252 } 253 254 /* 255 * Write out registers in core dump format, as defined by the 256 * struct user_regs_struct 257 */ 258 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs) 259 { 260 dest[0] = 0; /* r0 */ 261 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long)); 262 dest[32] = regs->pc; 263 dest[33] = regs->sr; 264 dest[34] = 0; 265 dest[35] = 0; 266 } 267 268 unsigned long get_wchan(struct task_struct *p) 269 { 270 /* TODO */ 271 272 return 0; 273 } 274