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 cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } }; 47 48 static inline int external_pid(void) 49 { 50 /* FIXME: Need to look up userspace_pid by cpu */ 51 return userspace_pid[0]; 52 } 53 54 void free_stack(unsigned long stack, int order) 55 { 56 free_pages(stack, order); 57 } 58 59 unsigned long alloc_stack(int order, int atomic) 60 { 61 unsigned long page; 62 gfp_t flags = GFP_KERNEL; 63 64 if (atomic) 65 flags = GFP_ATOMIC; 66 page = __get_free_pages(flags, order); 67 68 return page; 69 } 70 71 static inline void set_current(struct task_struct *task) 72 { 73 cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task) 74 { external_pid(), task }); 75 } 76 77 struct task_struct *__switch_to(struct task_struct *from, struct task_struct *to) 78 { 79 to->thread.prev_sched = from; 80 set_current(to); 81 82 switch_threads(&from->thread.switch_buf, &to->thread.switch_buf); 83 arch_switch_to(current); 84 85 return current->thread.prev_sched; 86 } 87 88 void interrupt_end(void) 89 { 90 struct pt_regs *regs = ¤t->thread.regs; 91 92 if (need_resched()) 93 schedule(); 94 if (test_thread_flag(TIF_SIGPENDING) || 95 test_thread_flag(TIF_NOTIFY_SIGNAL)) 96 do_signal(regs); 97 if (test_thread_flag(TIF_NOTIFY_RESUME)) 98 resume_user_mode_work(regs); 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 *), n; 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.u.thread.proc; 120 arg = current->thread.request.u.thread.arg; 121 122 /* 123 * callback returns only if the kernel thread execs a process 124 */ 125 n = fn(arg); 126 userspace(¤t->thread.regs.regs, current_thread_info()->aux_fp_regs); 127 } 128 129 /* Called magically, see new_thread_handler above */ 130 static void fork_handler(void) 131 { 132 force_flush_all(); 133 134 schedule_tail(current->thread.prev_sched); 135 136 /* 137 * XXX: if interrupt_end() calls schedule, this call to 138 * arch_switch_to isn't needed. We could want to apply this to 139 * improve performance. -bb 140 */ 141 arch_switch_to(current); 142 143 current->thread.prev_sched = NULL; 144 145 userspace(¤t->thread.regs.regs, current_thread_info()->aux_fp_regs); 146 } 147 148 int copy_thread(struct task_struct * p, const struct kernel_clone_args *args) 149 { 150 unsigned long clone_flags = args->flags; 151 unsigned long sp = args->stack; 152 unsigned long tls = args->tls; 153 void (*handler)(void); 154 int ret = 0; 155 156 p->thread = (struct thread_struct) INIT_THREAD; 157 158 if (!args->fn) { 159 memcpy(&p->thread.regs.regs, current_pt_regs(), 160 sizeof(p->thread.regs.regs)); 161 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0); 162 if (sp != 0) 163 REGS_SP(p->thread.regs.regs.gp) = sp; 164 165 handler = fork_handler; 166 167 arch_copy_thread(¤t->thread.arch, &p->thread.arch); 168 } else { 169 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp); 170 p->thread.request.u.thread.proc = args->fn; 171 p->thread.request.u.thread.arg = args->fn_arg; 172 handler = new_thread_handler; 173 } 174 175 new_thread(task_stack_page(p), &p->thread.switch_buf, handler); 176 177 if (!args->fn) { 178 clear_flushed_tls(p); 179 180 /* 181 * Set a new TLS for the child thread? 182 */ 183 if (clone_flags & CLONE_SETTLS) 184 ret = arch_set_tls(p, tls); 185 } 186 187 return ret; 188 } 189 190 void initial_thread_cb(void (*proc)(void *), void *arg) 191 { 192 int save_kmalloc_ok = kmalloc_ok; 193 194 kmalloc_ok = 0; 195 initial_thread_cb_skas(proc, arg); 196 kmalloc_ok = save_kmalloc_ok; 197 } 198 199 void um_idle_sleep(void) 200 { 201 if (time_travel_mode != TT_MODE_OFF) 202 time_travel_sleep(); 203 else 204 os_idle_sleep(); 205 } 206 207 void arch_cpu_idle(void) 208 { 209 cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); 210 um_idle_sleep(); 211 } 212 213 int __uml_cant_sleep(void) { 214 return in_atomic() || irqs_disabled() || in_interrupt(); 215 /* Is in_interrupt() really needed? */ 216 } 217 218 int user_context(unsigned long sp) 219 { 220 unsigned long stack; 221 222 stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER); 223 return stack != (unsigned long) current_thread_info(); 224 } 225 226 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end; 227 228 void do_uml_exitcalls(void) 229 { 230 exitcall_t *call; 231 232 call = &__uml_exitcall_end; 233 while (--call >= &__uml_exitcall_begin) 234 (*call)(); 235 } 236 237 char *uml_strdup(const char *string) 238 { 239 return kstrdup(string, GFP_KERNEL); 240 } 241 EXPORT_SYMBOL(uml_strdup); 242 243 int copy_from_user_proc(void *to, void __user *from, int size) 244 { 245 return copy_from_user(to, from, size); 246 } 247 248 static atomic_t using_sysemu = ATOMIC_INIT(0); 249 int sysemu_supported; 250 251 static void set_using_sysemu(int value) 252 { 253 if (value > sysemu_supported) 254 return; 255 atomic_set(&using_sysemu, value); 256 } 257 258 static int get_using_sysemu(void) 259 { 260 return atomic_read(&using_sysemu); 261 } 262 263 static int sysemu_proc_show(struct seq_file *m, void *v) 264 { 265 seq_printf(m, "%d\n", get_using_sysemu()); 266 return 0; 267 } 268 269 static int sysemu_proc_open(struct inode *inode, struct file *file) 270 { 271 return single_open(file, sysemu_proc_show, NULL); 272 } 273 274 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf, 275 size_t count, loff_t *pos) 276 { 277 char tmp[2]; 278 279 if (copy_from_user(tmp, buf, 1)) 280 return -EFAULT; 281 282 if (tmp[0] >= '0' && tmp[0] <= '2') 283 set_using_sysemu(tmp[0] - '0'); 284 /* We use the first char, but pretend to write everything */ 285 return count; 286 } 287 288 static const struct proc_ops sysemu_proc_ops = { 289 .proc_open = sysemu_proc_open, 290 .proc_read = seq_read, 291 .proc_lseek = seq_lseek, 292 .proc_release = single_release, 293 .proc_write = sysemu_proc_write, 294 }; 295 296 static int __init make_proc_sysemu(void) 297 { 298 struct proc_dir_entry *ent; 299 if (!sysemu_supported) 300 return 0; 301 302 ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_ops); 303 304 if (ent == NULL) 305 { 306 printk(KERN_WARNING "Failed to register /proc/sysemu\n"); 307 return 0; 308 } 309 310 return 0; 311 } 312 313 late_initcall(make_proc_sysemu); 314 315 int singlestepping(void) 316 { 317 return test_thread_flag(TIF_SINGLESTEP); 318 } 319 320 /* 321 * Only x86 and x86_64 have an arch_align_stack(). 322 * All other arches have "#define arch_align_stack(x) (x)" 323 * in their asm/exec.h 324 * As this is included in UML from asm-um/system-generic.h, 325 * we can use it to behave as the subarch does. 326 */ 327 #ifndef arch_align_stack 328 unsigned long arch_align_stack(unsigned long sp) 329 { 330 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 331 sp -= get_random_u32_below(8192); 332 return sp & ~0xf; 333 } 334 #endif 335 336 unsigned long __get_wchan(struct task_struct *p) 337 { 338 unsigned long stack_page, sp, ip; 339 bool seen_sched = 0; 340 341 stack_page = (unsigned long) task_stack_page(p); 342 /* Bail if the process has no kernel stack for some reason */ 343 if (stack_page == 0) 344 return 0; 345 346 sp = p->thread.switch_buf->JB_SP; 347 /* 348 * Bail if the stack pointer is below the bottom of the kernel 349 * stack for some reason 350 */ 351 if (sp < stack_page) 352 return 0; 353 354 while (sp < stack_page + THREAD_SIZE) { 355 ip = *((unsigned long *) sp); 356 if (in_sched_functions(ip)) 357 /* Ignore everything until we're above the scheduler */ 358 seen_sched = 1; 359 else if (kernel_text_address(ip) && seen_sched) 360 return ip; 361 362 sp += sizeof(unsigned long); 363 } 364 365 return 0; 366 } 367 368 int elf_core_copy_task_fpregs(struct task_struct *t, elf_fpregset_t *fpu) 369 { 370 int cpu = current_thread_info()->cpu; 371 372 return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu); 373 } 374 375