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/pgtable.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(void) 54 { 55 printk(KERN_INFO "*** MACHINE RESTART ***\n"); 56 __asm__("l.nop 1"); 57 } 58 59 /* 60 * Similar to machine_power_off, but don't shut off power. Add code 61 * here to freeze the system for e.g. post-mortem debug purpose when 62 * possible. This halt has nothing to do with the idle halt. 63 */ 64 void machine_halt(void) 65 { 66 printk(KERN_INFO "*** MACHINE HALT ***\n"); 67 __asm__("l.nop 1"); 68 } 69 70 /* If or when software power-off is implemented, add code here. */ 71 void machine_power_off(void) 72 { 73 printk(KERN_INFO "*** MACHINE POWER OFF ***\n"); 74 __asm__("l.nop 1"); 75 } 76 77 /* 78 * Send the doze signal to the cpu if available. 79 * Make sure, that all interrupts are enabled 80 */ 81 void arch_cpu_idle(void) 82 { 83 local_irq_enable(); 84 if (mfspr(SPR_UPR) & SPR_UPR_PMP) 85 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); 86 } 87 88 void (*pm_power_off) (void) = machine_power_off; 89 EXPORT_SYMBOL(pm_power_off); 90 91 /* 92 * When a process does an "exec", machine state like FPU and debug 93 * registers need to be reset. This is a hook function for that. 94 * Currently we don't have any such state to reset, so this is empty. 95 */ 96 void flush_thread(void) 97 { 98 } 99 100 void show_regs(struct pt_regs *regs) 101 { 102 extern void show_registers(struct pt_regs *regs); 103 104 show_regs_print_info(KERN_DEFAULT); 105 /* __PHX__ cleanup this mess */ 106 show_registers(regs); 107 } 108 109 void release_thread(struct task_struct *dead_task) 110 { 111 } 112 113 /* 114 * Copy the thread-specific (arch specific) info from the current 115 * process to the new one p 116 */ 117 extern asmlinkage void ret_from_fork(void); 118 119 /* 120 * copy_thread_tls 121 * @clone_flags: flags 122 * @usp: user stack pointer or fn for kernel thread 123 * @arg: arg to fn for kernel thread; always NULL for userspace thread 124 * @p: the newly created task 125 * @tls: the Thread Local Storage pointer for the new process 126 * 127 * At the top of a newly initialized kernel stack are two stacked pt_reg 128 * structures. The first (topmost) is the userspace context of the thread. 129 * The second is the kernelspace context of the thread. 130 * 131 * A kernel thread will not be returning to userspace, so the topmost pt_regs 132 * struct can be uninitialized; it _does_ need to exist, though, because 133 * a kernel thread can become a userspace thread by doing a kernel_execve, in 134 * which case the topmost context will be initialized and used for 'returning' 135 * to userspace. 136 * 137 * The second pt_reg struct needs to be initialized to 'return' to 138 * ret_from_fork. A kernel thread will need to set r20 to the address of 139 * a function to call into (with arg in r22); userspace threads need to set 140 * r20 to NULL in which case ret_from_fork will just continue a return to 141 * userspace. 142 * 143 * A kernel thread 'fn' may return; this is effectively what happens when 144 * kernel_execve is called. In that case, the userspace pt_regs must have 145 * been initialized (which kernel_execve takes care of, see start_thread 146 * below); ret_from_fork will then continue its execution causing the 147 * 'kernel thread' to return to userspace as a userspace thread. 148 */ 149 150 int 151 copy_thread_tls(unsigned long clone_flags, unsigned long usp, 152 unsigned long arg, struct task_struct *p, unsigned long tls) 153 { 154 struct pt_regs *userregs; 155 struct pt_regs *kregs; 156 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE; 157 unsigned long top_of_kernel_stack; 158 159 top_of_kernel_stack = sp; 160 161 /* Locate userspace context on stack... */ 162 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 163 sp -= sizeof(struct pt_regs); 164 userregs = (struct pt_regs *) sp; 165 166 /* ...and kernel context */ 167 sp -= STACK_FRAME_OVERHEAD; /* redzone */ 168 sp -= sizeof(struct pt_regs); 169 kregs = (struct pt_regs *)sp; 170 171 if (unlikely(p->flags & PF_KTHREAD)) { 172 memset(kregs, 0, sizeof(struct pt_regs)); 173 kregs->gpr[20] = usp; /* fn, kernel thread */ 174 kregs->gpr[22] = arg; 175 } else { 176 *userregs = *current_pt_regs(); 177 178 if (usp) 179 userregs->sp = usp; 180 181 /* 182 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer. 183 */ 184 if (clone_flags & CLONE_SETTLS) 185 userregs->gpr[10] = tls; 186 187 userregs->gpr[11] = 0; /* Result from fork() */ 188 189 kregs->gpr[20] = 0; /* Userspace thread */ 190 } 191 192 /* 193 * _switch wants the kernel stack page in pt_regs->sp so that it 194 * can restore it to thread_info->ksp... see _switch for details. 195 */ 196 kregs->sp = top_of_kernel_stack; 197 kregs->gpr[9] = (unsigned long)ret_from_fork; 198 199 task_thread_info(p)->ksp = (unsigned long)kregs; 200 201 return 0; 202 } 203 204 /* 205 * Set up a thread for executing a new program 206 */ 207 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 208 { 209 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM; 210 211 memset(regs, 0, sizeof(struct pt_regs)); 212 213 regs->pc = pc; 214 regs->sr = sr; 215 regs->sp = sp; 216 } 217 218 /* Fill in the fpu structure for a core dump. */ 219 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu) 220 { 221 /* TODO */ 222 return 0; 223 } 224 225 extern struct thread_info *_switch(struct thread_info *old_ti, 226 struct thread_info *new_ti); 227 extern int lwa_flag; 228 229 struct task_struct *__switch_to(struct task_struct *old, 230 struct task_struct *new) 231 { 232 struct task_struct *last; 233 struct thread_info *new_ti, *old_ti; 234 unsigned long flags; 235 236 local_irq_save(flags); 237 238 /* current_set is an array of saved current pointers 239 * (one for each cpu). we need them at user->kernel transition, 240 * while we save them at kernel->user transition 241 */ 242 new_ti = new->stack; 243 old_ti = old->stack; 244 245 lwa_flag = 0; 246 247 current_thread_info_set[smp_processor_id()] = new_ti; 248 last = (_switch(old_ti, new_ti))->task; 249 250 local_irq_restore(flags); 251 252 return last; 253 } 254 255 /* 256 * Write out registers in core dump format, as defined by the 257 * struct user_regs_struct 258 */ 259 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs) 260 { 261 dest[0] = 0; /* r0 */ 262 memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long)); 263 dest[32] = regs->pc; 264 dest[33] = regs->sr; 265 dest[34] = 0; 266 dest[35] = 0; 267 } 268 269 unsigned long get_wchan(struct task_struct *p) 270 { 271 /* TODO */ 272 273 return 0; 274 } 275