1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk}) 4 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) 5 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 6 * Copyright 2003 PathScale, Inc. 7 */ 8 9 #include <linux/stddef.h> 10 #include <linux/err.h> 11 #include <linux/hardirq.h> 12 #include <linux/mm.h> 13 #include <linux/module.h> 14 #include <linux/personality.h> 15 #include <linux/proc_fs.h> 16 #include <linux/ptrace.h> 17 #include <linux/random.h> 18 #include <linux/cpu.h> 19 #include <linux/slab.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/seq_file.h> 25 #include <linux/tick.h> 26 #include <linux/threads.h> 27 #include <linux/resume_user_mode.h> 28 #include <asm/current.h> 29 #include <asm/mmu_context.h> 30 #include <asm/switch_to.h> 31 #include <asm/exec.h> 32 #include <linux/uaccess.h> 33 #include <as-layout.h> 34 #include <kern_util.h> 35 #include <os.h> 36 #include <skas.h> 37 #include <registers.h> 38 #include <linux/time-internal.h> 39 #include <linux/elfcore.h> 40 41 /* 42 * This is a per-cpu array. A processor only modifies its entry and it only 43 * cares about its entry, so it's OK if another processor is modifying its 44 * entry. 45 */ 46 struct task_struct *cpu_tasks[NR_CPUS] = { 47 [0 ... NR_CPUS - 1] = &init_task, 48 }; 49 EXPORT_SYMBOL(cpu_tasks); 50 51 void free_stack(unsigned long stack, int order) 52 { 53 free_pages(stack, order); 54 } 55 56 unsigned long alloc_stack(int order, int atomic) 57 { 58 unsigned long page; 59 gfp_t flags = GFP_KERNEL; 60 61 if (atomic) 62 flags = GFP_ATOMIC; 63 page = __get_free_pages(flags, order); 64 65 return page; 66 } 67 68 static inline void set_current(struct task_struct *task) 69 { 70 cpu_tasks[task_thread_info(task)->cpu] = task; 71 } 72 73 struct task_struct *__switch_to(struct task_struct *from, struct task_struct *to) 74 { 75 to->thread.prev_sched = from; 76 set_current(to); 77 78 switch_threads(&from->thread.switch_buf, &to->thread.switch_buf); 79 arch_switch_to(current); 80 81 return current->thread.prev_sched; 82 } 83 84 void interrupt_end(void) 85 { 86 struct pt_regs *regs = ¤t->thread.regs; 87 unsigned long thread_flags; 88 89 thread_flags = read_thread_flags(); 90 while (thread_flags & _TIF_WORK_MASK) { 91 if (thread_flags & _TIF_NEED_RESCHED) 92 schedule(); 93 if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) 94 do_signal(regs); 95 if (thread_flags & _TIF_NOTIFY_RESUME) 96 resume_user_mode_work(regs); 97 thread_flags = read_thread_flags(); 98 } 99 } 100 101 int get_current_pid(void) 102 { 103 return task_pid_nr(current); 104 } 105 106 /* 107 * This is called magically, by its address being stuffed in a jmp_buf 108 * and being longjmp-d to. 109 */ 110 void new_thread_handler(void) 111 { 112 int (*fn)(void *); 113 void *arg; 114 115 if (current->thread.prev_sched != NULL) 116 schedule_tail(current->thread.prev_sched); 117 current->thread.prev_sched = NULL; 118 119 fn = current->thread.request.thread.proc; 120 arg = current->thread.request.thread.arg; 121 122 /* 123 * callback returns only if the kernel thread execs a process 124 */ 125 fn(arg); 126 userspace(¤t->thread.regs.regs); 127 } 128 129 /* Called magically, see new_thread_handler above */ 130 static void fork_handler(void) 131 { 132 schedule_tail(current->thread.prev_sched); 133 134 /* 135 * XXX: if interrupt_end() calls schedule, this call to 136 * arch_switch_to isn't needed. We could want to apply this to 137 * improve performance. -bb 138 */ 139 arch_switch_to(current); 140 141 current->thread.prev_sched = NULL; 142 143 userspace(¤t->thread.regs.regs); 144 } 145 146 int copy_thread(struct task_struct * p, const struct kernel_clone_args *args) 147 { 148 u64 clone_flags = args->flags; 149 unsigned long sp = args->stack; 150 unsigned long tls = args->tls; 151 void (*handler)(void); 152 int ret = 0; 153 154 p->thread = (struct thread_struct) INIT_THREAD; 155 156 if (!args->fn) { 157 memcpy(&p->thread.regs.regs, current_pt_regs(), 158 sizeof(p->thread.regs.regs)); 159 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0); 160 if (sp != 0) 161 REGS_SP(p->thread.regs.regs.gp) = sp; 162 163 handler = fork_handler; 164 165 arch_copy_thread(¤t->thread.arch, &p->thread.arch); 166 } else { 167 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp); 168 p->thread.request.thread.proc = args->fn; 169 p->thread.request.thread.arg = args->fn_arg; 170 handler = new_thread_handler; 171 } 172 173 new_thread(task_stack_page(p), &p->thread.switch_buf, handler); 174 175 if (!args->fn) { 176 clear_flushed_tls(p); 177 178 /* 179 * Set a new TLS for the child thread? 180 */ 181 if (clone_flags & CLONE_SETTLS) 182 ret = arch_set_tls(p, tls); 183 } 184 185 return ret; 186 } 187 188 void initial_thread_cb(void (*proc)(void *), void *arg) 189 { 190 initial_thread_cb_skas(proc, arg); 191 } 192 193 int arch_dup_task_struct(struct task_struct *dst, 194 struct task_struct *src) 195 { 196 /* init_task is not dynamically sized (missing FPU state) */ 197 if (unlikely(src == &init_task)) { 198 memcpy(dst, src, sizeof(init_task)); 199 memset((void *)dst + sizeof(init_task), 0, 200 arch_task_struct_size - sizeof(init_task)); 201 } else { 202 memcpy(dst, src, arch_task_struct_size); 203 } 204 205 return 0; 206 } 207 208 void um_idle_sleep(void) 209 { 210 if (time_travel_mode != TT_MODE_OFF) 211 time_travel_sleep(); 212 else 213 os_idle_sleep(); 214 } 215 216 void arch_cpu_idle(void) 217 { 218 um_idle_sleep(); 219 } 220 221 void arch_cpu_idle_prepare(void) 222 { 223 os_idle_prepare(); 224 } 225 226 int __uml_cant_sleep(void) { 227 return in_atomic() || irqs_disabled() || in_interrupt(); 228 /* Is in_interrupt() really needed? */ 229 } 230 231 int uml_need_resched(void) 232 { 233 return need_resched(); 234 } 235 236 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end; 237 238 void do_uml_exitcalls(void) 239 { 240 exitcall_t *call; 241 242 call = &__uml_exitcall_end; 243 while (--call >= &__uml_exitcall_begin) 244 (*call)(); 245 } 246 247 char *uml_strdup(const char *string) 248 { 249 return kstrdup(string, GFP_KERNEL); 250 } 251 EXPORT_SYMBOL(uml_strdup); 252 253 int copy_from_user_proc(void *to, void __user *from, int size) 254 { 255 return copy_from_user(to, from, size); 256 } 257 258 int singlestepping(void) 259 { 260 return test_thread_flag(TIF_SINGLESTEP); 261 } 262 263 /* 264 * Only x86 and x86_64 have an arch_align_stack(). 265 * All other arches have "#define arch_align_stack(x) (x)" 266 * in their asm/exec.h 267 * As this is included in UML from asm-um/system-generic.h, 268 * we can use it to behave as the subarch does. 269 */ 270 #ifndef arch_align_stack 271 unsigned long arch_align_stack(unsigned long sp) 272 { 273 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 274 sp -= get_random_u32_below(8192); 275 return sp & ~0xf; 276 } 277 #endif 278 279 unsigned long __get_wchan(struct task_struct *p) 280 { 281 unsigned long stack_page, sp, ip; 282 bool seen_sched = 0; 283 284 stack_page = (unsigned long) task_stack_page(p); 285 /* Bail if the process has no kernel stack for some reason */ 286 if (stack_page == 0) 287 return 0; 288 289 sp = p->thread.switch_buf->JB_SP; 290 /* 291 * Bail if the stack pointer is below the bottom of the kernel 292 * stack for some reason 293 */ 294 if (sp < stack_page) 295 return 0; 296 297 while (sp < stack_page + THREAD_SIZE) { 298 ip = *((unsigned long *) sp); 299 if (in_sched_functions(ip)) 300 /* Ignore everything until we're above the scheduler */ 301 seen_sched = 1; 302 else if (kernel_text_address(ip) && seen_sched) 303 return ip; 304 305 sp += sizeof(unsigned long); 306 } 307 308 return 0; 309 } 310