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