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 <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> 24 #include <linux/mm.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> 34 #include <linux/fs.h> 35 #include <linux/reboot.h> 36 37 #include <linux/uaccess.h> 38 #include <asm/io.h> 39 #include <asm/processor.h> 40 #include <asm/spr_defs.h> 41 42 #include <linux/smp.h> 43 44 /* 45 * Pointer to Current thread info structure. 46 * 47 * Used at user space -> kernel transitions. 48 */ 49 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, }; 50 51 void machine_restart(char *cmd) 52 { 53 do_kernel_restart(cmd); 54 55 /* Give a grace period for failure to restart of 1s */ 56 mdelay(1000); 57 58 /* Whoops - the platform was unable to reboot. Tell the user! */ 59 pr_emerg("Reboot failed -- System halted\n"); 60 while (1); 61 } 62 63 /* 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. 67 */ 68 void machine_halt(void) 69 { 70 printk(KERN_INFO "*** MACHINE HALT ***\n"); 71 __asm__("l.nop 1"); 72 } 73 74 /* If or when software power-off is implemented, add code here. */ 75 void machine_power_off(void) 76 { 77 printk(KERN_INFO "*** MACHINE POWER OFF ***\n"); 78 __asm__("l.nop 1"); 79 } 80 81 /* 82 * Send the doze signal to the cpu if available. 83 * Make sure, that all interrupts are enabled 84 */ 85 void arch_cpu_idle(void) 86 { 87 raw_local_irq_enable(); 88 if (mfspr(SPR_UPR) & SPR_UPR_PMP) 89 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); 90 } 91 92 void (*pm_power_off) (void) = machine_power_off; 93 EXPORT_SYMBOL(pm_power_off); 94 95 /* 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. 99 */ 100 void flush_thread(void) 101 { 102 } 103 104 void show_regs(struct pt_regs *regs) 105 { 106 extern void show_registers(struct pt_regs *regs); 107 108 show_regs_print_info(KERN_DEFAULT); 109 /* __PHX__ cleanup this mess */ 110 show_registers(regs); 111 } 112 113 void release_thread(struct task_struct *dead_task) 114 { 115 } 116 117 /* 118 * Copy the thread-specific (arch specific) info from the current 119 * process to the new one p 120 */ 121 extern asmlinkage void ret_from_fork(void); 122 123 /* 124 * copy_thread 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 130 * 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. 134 * 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' 139 * to userspace. 140 * 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 145 * userspace. 146 * 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. 152 */ 153 154 int 155 copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg, 156 struct task_struct *p, unsigned long tls) 157 { 158 struct pt_regs *userregs; 159 struct pt_regs *kregs; 160 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE; 161 unsigned long top_of_kernel_stack; 162 163 top_of_kernel_stack = sp; 164 165 /* Locate userspace context on stack... */ 166 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 167 sp -= sizeof(struct pt_regs); 168 userregs = (struct pt_regs *) sp; 169 170 /* ...and kernel context */ 171 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 172 sp -= sizeof(struct pt_regs); 173 kregs = (struct pt_regs *)sp; 174 175 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { 176 memset(kregs, 0, sizeof(struct pt_regs)); 177 kregs->gpr[20] = usp; /* fn, kernel thread */ 178 kregs->gpr[22] = arg; 179 } else { 180 *userregs = *current_pt_regs(); 181 182 if (usp) 183 userregs->sp = usp; 184 185 /* 186 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer. 187 */ 188 if (clone_flags & CLONE_SETTLS) 189 userregs->gpr[10] = tls; 190 191 userregs->gpr[11] = 0; /* Result from fork() */ 192 193 kregs->gpr[20] = 0; /* Userspace thread */ 194 } 195 196 /* 197 * _switch wants the kernel stack page in pt_regs->sp so that it 198 * can restore it to thread_info->ksp... see _switch for details. 199 */ 200 kregs->sp = top_of_kernel_stack; 201 kregs->gpr[9] = (unsigned long)ret_from_fork; 202 203 task_thread_info(p)->ksp = (unsigned long)kregs; 204 205 return 0; 206 } 207 208 /* 209 * Set up a thread for executing a new program 210 */ 211 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 212 { 213 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM; 214 215 memset(regs, 0, sizeof(struct pt_regs)); 216 217 regs->pc = pc; 218 regs->sr = sr; 219 regs->sp = sp; 220 } 221 222 extern struct thread_info *_switch(struct thread_info *old_ti, 223 struct thread_info *new_ti); 224 extern int lwa_flag; 225 226 struct task_struct *__switch_to(struct task_struct *old, 227 struct task_struct *new) 228 { 229 struct task_struct *last; 230 struct thread_info *new_ti, *old_ti; 231 unsigned long flags; 232 233 local_irq_save(flags); 234 235 /* current_set is an array of saved current pointers 236 * (one for each cpu). we need them at user->kernel transition, 237 * while we save them at kernel->user transition 238 */ 239 new_ti = new->stack; 240 old_ti = old->stack; 241 242 lwa_flag = 0; 243 244 current_thread_info_set[smp_processor_id()] = new_ti; 245 last = (_switch(old_ti, new_ti))->task; 246 247 local_irq_restore(flags); 248 249 return last; 250 } 251 252 /* 253 * Write out registers in core dump format, as defined by the 254 * struct user_regs_struct 255 */ 256 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs) 257 { 258 dest[0] = 0; /* r0 */ 259 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long)); 260 dest[32] = regs->pc; 261 dest[33] = regs->sr; 262 dest[34] = 0; 263 dest[35] = 0; 264 } 265 266 unsigned long get_wchan(struct task_struct *p) 267 { 268 /* TODO */ 269 270 return 0; 271 } 272