linux/arch/um/kernel/process.c
<<
>>
Prefs
   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/slab.h>
  19#include <linux/sched.h>
  20#include <linux/sched/debug.h>
  21#include <linux/sched/task.h>
  22#include <linux/sched/task_stack.h>
  23#include <linux/seq_file.h>
  24#include <linux/tick.h>
  25#include <linux/threads.h>
  26#include <linux/tracehook.h>
  27#include <asm/current.h>
  28#include <asm/mmu_context.h>
  29#include <linux/uaccess.h>
  30#include <as-layout.h>
  31#include <kern_util.h>
  32#include <os.h>
  33#include <skas.h>
  34#include <linux/time-internal.h>
  35
  36/*
  37 * This is a per-cpu array.  A processor only modifies its entry and it only
  38 * cares about its entry, so it's OK if another processor is modifying its
  39 * entry.
  40 */
  41struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
  42
  43static inline int external_pid(void)
  44{
  45        /* FIXME: Need to look up userspace_pid by cpu */
  46        return userspace_pid[0];
  47}
  48
  49int pid_to_processor_id(int pid)
  50{
  51        int i;
  52
  53        for (i = 0; i < ncpus; i++) {
  54                if (cpu_tasks[i].pid == pid)
  55                        return i;
  56        }
  57        return -1;
  58}
  59
  60void free_stack(unsigned long stack, int order)
  61{
  62        free_pages(stack, order);
  63}
  64
  65unsigned long alloc_stack(int order, int atomic)
  66{
  67        unsigned long page;
  68        gfp_t flags = GFP_KERNEL;
  69
  70        if (atomic)
  71                flags = GFP_ATOMIC;
  72        page = __get_free_pages(flags, order);
  73
  74        return page;
  75}
  76
  77static inline void set_current(struct task_struct *task)
  78{
  79        cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  80                { external_pid(), task });
  81}
  82
  83extern void arch_switch_to(struct task_struct *to);
  84
  85void *__switch_to(struct task_struct *from, struct task_struct *to)
  86{
  87        to->thread.prev_sched = from;
  88        set_current(to);
  89
  90        switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
  91        arch_switch_to(current);
  92
  93        return current->thread.prev_sched;
  94}
  95
  96void interrupt_end(void)
  97{
  98        struct pt_regs *regs = &current->thread.regs;
  99
 100        if (need_resched())
 101                schedule();
 102        if (test_thread_flag(TIF_SIGPENDING) ||
 103            test_thread_flag(TIF_NOTIFY_SIGNAL))
 104                do_signal(regs);
 105        if (test_thread_flag(TIF_NOTIFY_RESUME))
 106                tracehook_notify_resume(regs);
 107}
 108
 109int get_current_pid(void)
 110{
 111        return task_pid_nr(current);
 112}
 113
 114/*
 115 * This is called magically, by its address being stuffed in a jmp_buf
 116 * and being longjmp-d to.
 117 */
 118void new_thread_handler(void)
 119{
 120        int (*fn)(void *), n;
 121        void *arg;
 122
 123        if (current->thread.prev_sched != NULL)
 124                schedule_tail(current->thread.prev_sched);
 125        current->thread.prev_sched = NULL;
 126
 127        fn = current->thread.request.u.thread.proc;
 128        arg = current->thread.request.u.thread.arg;
 129
 130        /*
 131         * callback returns only if the kernel thread execs a process
 132         */
 133        n = fn(arg);
 134        userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 135}
 136
 137/* Called magically, see new_thread_handler above */
 138void fork_handler(void)
 139{
 140        force_flush_all();
 141
 142        schedule_tail(current->thread.prev_sched);
 143
 144        /*
 145         * XXX: if interrupt_end() calls schedule, this call to
 146         * arch_switch_to isn't needed. We could want to apply this to
 147         * improve performance. -bb
 148         */
 149        arch_switch_to(current);
 150
 151        current->thread.prev_sched = NULL;
 152
 153        userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 154}
 155
 156int copy_thread(unsigned long clone_flags, unsigned long sp,
 157                unsigned long arg, struct task_struct * p, unsigned long tls)
 158{
 159        void (*handler)(void);
 160        int kthread = current->flags & (PF_KTHREAD | PF_IO_WORKER);
 161        int ret = 0;
 162
 163        p->thread = (struct thread_struct) INIT_THREAD;
 164
 165        if (!kthread) {
 166                memcpy(&p->thread.regs.regs, current_pt_regs(),
 167                       sizeof(p->thread.regs.regs));
 168                PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
 169                if (sp != 0)
 170                        REGS_SP(p->thread.regs.regs.gp) = sp;
 171
 172                handler = fork_handler;
 173
 174                arch_copy_thread(&current->thread.arch, &p->thread.arch);
 175        } else {
 176                get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
 177                p->thread.request.u.thread.proc = (int (*)(void *))sp;
 178                p->thread.request.u.thread.arg = (void *)arg;
 179                handler = new_thread_handler;
 180        }
 181
 182        new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 183
 184        if (!kthread) {
 185                clear_flushed_tls(p);
 186
 187                /*
 188                 * Set a new TLS for the child thread?
 189                 */
 190                if (clone_flags & CLONE_SETTLS)
 191                        ret = arch_set_tls(p, tls);
 192        }
 193
 194        return ret;
 195}
 196
 197void initial_thread_cb(void (*proc)(void *), void *arg)
 198{
 199        int save_kmalloc_ok = kmalloc_ok;
 200
 201        kmalloc_ok = 0;
 202        initial_thread_cb_skas(proc, arg);
 203        kmalloc_ok = save_kmalloc_ok;
 204}
 205
 206void um_idle_sleep(void)
 207{
 208        if (time_travel_mode != TT_MODE_OFF)
 209                time_travel_sleep();
 210        else
 211                os_idle_sleep();
 212}
 213
 214void arch_cpu_idle(void)
 215{
 216        cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 217        um_idle_sleep();
 218        raw_local_irq_enable();
 219}
 220
 221int __cant_sleep(void) {
 222        return in_atomic() || irqs_disabled() || in_interrupt();
 223        /* Is in_interrupt() really needed? */
 224}
 225
 226int user_context(unsigned long sp)
 227{
 228        unsigned long stack;
 229
 230        stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 231        return stack != (unsigned long) current_thread_info();
 232}
 233
 234extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 235
 236void do_uml_exitcalls(void)
 237{
 238        exitcall_t *call;
 239
 240        call = &__uml_exitcall_end;
 241        while (--call >= &__uml_exitcall_begin)
 242                (*call)();
 243}
 244
 245char *uml_strdup(const char *string)
 246{
 247        return kstrdup(string, GFP_KERNEL);
 248}
 249EXPORT_SYMBOL(uml_strdup);
 250
 251int copy_to_user_proc(void __user *to, void *from, int size)
 252{
 253        return copy_to_user(to, from, size);
 254}
 255
 256int copy_from_user_proc(void *to, void __user *from, int size)
 257{
 258        return copy_from_user(to, from, size);
 259}
 260
 261int clear_user_proc(void __user *buf, int size)
 262{
 263        return clear_user(buf, size);
 264}
 265
 266int cpu(void)
 267{
 268        return current_thread_info()->cpu;
 269}
 270
 271static atomic_t using_sysemu = ATOMIC_INIT(0);
 272int sysemu_supported;
 273
 274void set_using_sysemu(int value)
 275{
 276        if (value > sysemu_supported)
 277                return;
 278        atomic_set(&using_sysemu, value);
 279}
 280
 281int get_using_sysemu(void)
 282{
 283        return atomic_read(&using_sysemu);
 284}
 285
 286static int sysemu_proc_show(struct seq_file *m, void *v)
 287{
 288        seq_printf(m, "%d\n", get_using_sysemu());
 289        return 0;
 290}
 291
 292static int sysemu_proc_open(struct inode *inode, struct file *file)
 293{
 294        return single_open(file, sysemu_proc_show, NULL);
 295}
 296
 297static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 298                                 size_t count, loff_t *pos)
 299{
 300        char tmp[2];
 301
 302        if (copy_from_user(tmp, buf, 1))
 303                return -EFAULT;
 304
 305        if (tmp[0] >= '0' && tmp[0] <= '2')
 306                set_using_sysemu(tmp[0] - '0');
 307        /* We use the first char, but pretend to write everything */
 308        return count;
 309}
 310
 311static const struct proc_ops sysemu_proc_ops = {
 312        .proc_open      = sysemu_proc_open,
 313        .proc_read      = seq_read,
 314        .proc_lseek     = seq_lseek,
 315        .proc_release   = single_release,
 316        .proc_write     = sysemu_proc_write,
 317};
 318
 319int __init make_proc_sysemu(void)
 320{
 321        struct proc_dir_entry *ent;
 322        if (!sysemu_supported)
 323                return 0;
 324
 325        ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_ops);
 326
 327        if (ent == NULL)
 328        {
 329                printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 330                return 0;
 331        }
 332
 333        return 0;
 334}
 335
 336late_initcall(make_proc_sysemu);
 337
 338int singlestepping(void * t)
 339{
 340        struct task_struct *task = t ? t : current;
 341
 342        if (!(task->ptrace & PT_DTRACE))
 343                return 0;
 344
 345        if (task->thread.singlestep_syscall)
 346                return 1;
 347
 348        return 2;
 349}
 350
 351/*
 352 * Only x86 and x86_64 have an arch_align_stack().
 353 * All other arches have "#define arch_align_stack(x) (x)"
 354 * in their asm/exec.h
 355 * As this is included in UML from asm-um/system-generic.h,
 356 * we can use it to behave as the subarch does.
 357 */
 358#ifndef arch_align_stack
 359unsigned long arch_align_stack(unsigned long sp)
 360{
 361        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 362                sp -= get_random_int() % 8192;
 363        return sp & ~0xf;
 364}
 365#endif
 366
 367unsigned long get_wchan(struct task_struct *p)
 368{
 369        unsigned long stack_page, sp, ip;
 370        bool seen_sched = 0;
 371
 372        if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 373                return 0;
 374
 375        stack_page = (unsigned long) task_stack_page(p);
 376        /* Bail if the process has no kernel stack for some reason */
 377        if (stack_page == 0)
 378                return 0;
 379
 380        sp = p->thread.switch_buf->JB_SP;
 381        /*
 382         * Bail if the stack pointer is below the bottom of the kernel
 383         * stack for some reason
 384         */
 385        if (sp < stack_page)
 386                return 0;
 387
 388        while (sp < stack_page + THREAD_SIZE) {
 389                ip = *((unsigned long *) sp);
 390                if (in_sched_functions(ip))
 391                        /* Ignore everything until we're above the scheduler */
 392                        seen_sched = 1;
 393                else if (kernel_text_address(ip) && seen_sched)
 394                        return ip;
 395
 396                sp += sizeof(unsigned long);
 397        }
 398
 399        return 0;
 400}
 401
 402int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 403{
 404        int cpu = current_thread_info()->cpu;
 405
 406        return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
 407}
 408
 409