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 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 } 267