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 #include <linux/reboot.h> 38 39 #include <linux/uaccess.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(char *cmd) 54 { 55 do_kernel_restart(cmd); 56 57 /* Give a grace period for failure to restart of 1s */ 58 mdelay(1000); 59 60 /* Whoops - the platform was unable to reboot. Tell the user! */ 61 pr_emerg("Reboot failed -- System halted\n"); 62 while (1); 63 } 64 65 /* 66 * Similar to machine_power_off, but don't shut off power. Add code 67 * here to freeze the system for e.g. post-mortem debug purpose when 68 * possible. This halt has nothing to do with the idle halt. 69 */ 70 void machine_halt(void) 71 { 72 printk(KERN_INFO "*** MACHINE HALT ***\n"); 73 __asm__("l.nop 1"); 74 } 75 76 /* If or when software power-off is implemented, add code here. */ 77 void machine_power_off(void) 78 { 79 printk(KERN_INFO "*** MACHINE POWER OFF ***\n"); 80 __asm__("l.nop 1"); 81 } 82 83 /* 84 * Send the doze signal to the cpu if available. 85 * Make sure, that all interrupts are enabled 86 */ 87 void arch_cpu_idle(void) 88 { 89 raw_local_irq_enable(); 90 if (mfspr(SPR_UPR) & SPR_UPR_PMP) 91 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); 92 } 93 94 void (*pm_power_off) (void) = machine_power_off; 95 EXPORT_SYMBOL(pm_power_off); 96 97 /* 98 * When a process does an "exec", machine state like FPU and debug 99 * registers need to be reset. This is a hook function for that. 100 * Currently we don't have any such state to reset, so this is empty. 101 */ 102 void flush_thread(void) 103 { 104 } 105 106 void show_regs(struct pt_regs *regs) 107 { 108 extern void show_registers(struct pt_regs *regs); 109 110 show_regs_print_info(KERN_DEFAULT); 111 /* __PHX__ cleanup this mess */ 112 show_registers(regs); 113 } 114 115 void release_thread(struct task_struct *dead_task) 116 { 117 } 118 119 /* 120 * Copy the thread-specific (arch specific) info from the current 121 * process to the new one p 122 */ 123 extern asmlinkage void ret_from_fork(void); 124 125 /* 126 * copy_thread 127 * @clone_flags: flags 128 * @usp: user stack pointer or fn for kernel thread 129 * @arg: arg to fn for kernel thread; always NULL for userspace thread 130 * @p: the newly created task 131 * @tls: the Thread Local Storage pointer for the new process 132 * 133 * At the top of a newly initialized kernel stack are two stacked pt_reg 134 * structures. The first (topmost) is the userspace context of the thread. 135 * The second is the kernelspace context of the thread. 136 * 137 * A kernel thread will not be returning to userspace, so the topmost pt_regs 138 * struct can be uninitialized; it _does_ need to exist, though, because 139 * a kernel thread can become a userspace thread by doing a kernel_execve, in 140 * which case the topmost context will be initialized and used for 'returning' 141 * to userspace. 142 * 143 * The second pt_reg struct needs to be initialized to 'return' to 144 * ret_from_fork. A kernel thread will need to set r20 to the address of 145 * a function to call into (with arg in r22); userspace threads need to set 146 * r20 to NULL in which case ret_from_fork will just continue a return to 147 * userspace. 148 * 149 * A kernel thread 'fn' may return; this is effectively what happens when 150 * kernel_execve is called. In that case, the userspace pt_regs must have 151 * been initialized (which kernel_execve takes care of, see start_thread 152 * below); ret_from_fork will then continue its execution causing the 153 * 'kernel thread' to return to userspace as a userspace thread. 154 */ 155 156 int 157 copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg, 158 struct task_struct *p, unsigned long tls) 159 { 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; 164 165 top_of_kernel_stack = sp; 166 167 /* Locate userspace context on stack... */ 168 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 169 sp -= sizeof(struct pt_regs); 170 userregs = (struct pt_regs *) sp; 171 172 /* ...and kernel context */ 173 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 174 sp -= sizeof(struct pt_regs); 175 kregs = (struct pt_regs *)sp; 176 177 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { 178 memset(kregs, 0, sizeof(struct pt_regs)); 179 kregs->gpr[20] = usp; /* fn, kernel thread */ 180 kregs->gpr[22] = arg; 181 } else { 182 *userregs = *current_pt_regs(); 183 184 if (usp) 185 userregs->sp = usp; 186 187 /* 188 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer. 189 */ 190 if (clone_flags & CLONE_SETTLS) 191 userregs->gpr[10] = tls; 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 extern struct thread_info *_switch(struct thread_info *old_ti, 225 struct thread_info *new_ti); 226 extern int lwa_flag; 227 228 struct task_struct *__switch_to(struct task_struct *old, 229 struct task_struct *new) 230 { 231 struct task_struct *last; 232 struct thread_info *new_ti, *old_ti; 233 unsigned long flags; 234 235 local_irq_save(flags); 236 237 /* 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 240 */ 241 new_ti = new->stack; 242 old_ti = old->stack; 243 244 lwa_flag = 0; 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