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