arch/um/kernel/process.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright 2003 PathScale, Inc.
  */

 #include <linux/stddef.h>
 #include <linux/err.h>
 #include <linux/hardirq.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/personality.h>
 #include <linux/proc_fs.h>
 #include <linux/ptrace.h>
 #include <linux/random.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
 #include <linux/seq_file.h>
 #include <linux/tick.h>
 #include <linux/threads.h>
 #include <linux/tracehook.h>
 #include <asm/current.h>
 #include <asm/mmu_context.h>
 #include <linux/uaccess.h>
 #include <as-layout.h>
 #include <kern_util.h>
 #include <os.h>
 #include <skas.h>
 #include <linux/time-internal.h>

 /*
  * This is a per-cpu array.  A processor only modifies its entry and it only
  * cares about its entry, so it's OK if another processor is modifying its
  * entry.
  */
 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };

 static inline int external_pid(void)
 {
 	/* FIXME: Need to look up userspace_pid by cpu */
 	return userspace_pid[0];
 }

 int pid_to_processor_id(int pid)
 {
 	int i;

 	for (i = 0; i < ncpus; i++) {
 		if (cpu_tasks[i].pid == pid)
 			return i;
 	}
 	return -1;
 }

 void free_stack(unsigned long stack, int order)
 {
 	free_pages(stack, order);
 }

 unsigned long alloc_stack(int order, int atomic)
 {
 	unsigned long page;
 	gfp_t flags = GFP_KERNEL;

 	if (atomic)
 		flags = GFP_ATOMIC;
 	page = __get_free_pages(flags, order);

 	return page;
 }

 static inline void set_current(struct task_struct *task)
 {
 	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
 		{ external_pid(), task });
 }

 extern void arch_switch_to(struct task_struct *to);

 void *__switch_to(struct task_struct *from, struct task_struct *to)
 {
 	to->thread.prev_sched = from;
 	set_current(to);

 	switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
 	arch_switch_to(current);

 	return current->thread.prev_sched;
 }

 void interrupt_end(void)
 {
 	struct pt_regs *regs = &current->thread.regs;

 	if (need_resched())
 		schedule();
 	if (test_thread_flag(TIF_SIGPENDING))
 		do_signal(regs);
 	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 		tracehook_notify_resume(regs);
 }

 int get_current_pid(void)
 {
 	return task_pid_nr(current);
 }

 /*
  * This is called magically, by its address being stuffed in a jmp_buf
  * and being longjmp-d to.
  */
 void new_thread_handler(void)
 {
 	int (*fn)(void *), n;
 	void *arg;

 	if (current->thread.prev_sched != NULL)
 		schedule_tail(current->thread.prev_sched);
 	current->thread.prev_sched = NULL;

 	fn = current->thread.request.u.thread.proc;
 	arg = current->thread.request.u.thread.arg;

 	/*
 	 * callback returns only if the kernel thread execs a process
 	 */
 	n = fn(arg);
 	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 }

 /* Called magically, see new_thread_handler above */
 void fork_handler(void)
 {
 	force_flush_all();

 	schedule_tail(current->thread.prev_sched);

 	/*
 	 * XXX: if interrupt_end() calls schedule, this call to
 	 * arch_switch_to isn't needed. We could want to apply this to
 	 * improve performance. -bb
 	 */
 	arch_switch_to(current);

 	current->thread.prev_sched = NULL;

 	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 }

 int copy_thread(unsigned long clone_flags, unsigned long sp,
 		unsigned long arg, struct task_struct * p, unsigned long tls)
 {
 	void (*handler)(void);
 	int kthread = current->flags & PF_KTHREAD;
 	int ret = 0;

 	p->thread = (struct thread_struct) INIT_THREAD;

 	if (!kthread) {
 	  	memcpy(&p->thread.regs.regs, current_pt_regs(),
 		       sizeof(p->thread.regs.regs));
 		PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
 		if (sp != 0)
 			REGS_SP(p->thread.regs.regs.gp) = sp;

 		handler = fork_handler;

 		arch_copy_thread(&current->thread.arch, &p->thread.arch);
 	} else {
 		get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
 		p->thread.request.u.thread.proc = (int (*)(void *))sp;
 		p->thread.request.u.thread.arg = (void *)arg;
 		handler = new_thread_handler;
 	}

 	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);

 	if (!kthread) {
 		clear_flushed_tls(p);

 		/*
 		 * Set a new TLS for the child thread?
 		 */
 		if (clone_flags & CLONE_SETTLS)
 			ret = arch_set_tls(p, tls);
 	}

 	return ret;
 }

 void initial_thread_cb(void (*proc)(void *), void *arg)
 {
 	int save_kmalloc_ok = kmalloc_ok;

 	kmalloc_ok = 0;
 	initial_thread_cb_skas(proc, arg);
 	kmalloc_ok = save_kmalloc_ok;
 }

 static void um_idle_sleep(void)
 {
 	unsigned long long duration = UM_NSEC_PER_SEC;

 	if (time_travel_mode != TT_MODE_OFF) {
 		time_travel_sleep(duration);
 	} else {
 		os_idle_sleep(duration);
 	}
 }

 void arch_cpu_idle(void)
 {
 	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 	um_idle_sleep();
 	local_irq_enable();
 }

 int __cant_sleep(void) {
 	return in_atomic() || irqs_disabled() || in_interrupt();
 	/* Is in_interrupt() really needed? */
 }

 int user_context(unsigned long sp)
 {
 	unsigned long stack;

 	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 	return stack != (unsigned long) current_thread_info();
 }

 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;

 void do_uml_exitcalls(void)
 {
 	exitcall_t *call;

 	call = &__uml_exitcall_end;
 	while (--call >= &__uml_exitcall_begin)
 		(*call)();
 }

 char *uml_strdup(const char *string)
 {
 	return kstrdup(string, GFP_KERNEL);
 }
 EXPORT_SYMBOL(uml_strdup);

 int copy_to_user_proc(void __user *to, void *from, int size)
 {
 	return copy_to_user(to, from, size);
 }

 int copy_from_user_proc(void *to, void __user *from, int size)
 {
 	return copy_from_user(to, from, size);
 }

 int clear_user_proc(void __user *buf, int size)
 {
 	return clear_user(buf, size);
 }

 int cpu(void)
 {
 	return current_thread_info()->cpu;
 }

 static atomic_t using_sysemu = ATOMIC_INIT(0);
 int sysemu_supported;

 void set_using_sysemu(int value)
 {
 	if (value > sysemu_supported)
 		return;
 	atomic_set(&using_sysemu, value);
 }

 int get_using_sysemu(void)
 {
 	return atomic_read(&using_sysemu);
 }

 static int sysemu_proc_show(struct seq_file *m, void *v)
 {
 	seq_printf(m, "%d\n", get_using_sysemu());
 	return 0;
 }

 static int sysemu_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, sysemu_proc_show, NULL);
 }

 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 				 size_t count, loff_t *pos)
 {
 	char tmp[2];

 	if (copy_from_user(tmp, buf, 1))
 		return -EFAULT;

 	if (tmp[0] >= '0' && tmp[0] <= '2')
 		set_using_sysemu(tmp[0] - '0');
 	/* We use the first char, but pretend to write everything */
 	return count;
 }

 static const struct proc_ops sysemu_proc_ops = {
 	.proc_open	= sysemu_proc_open,
 	.proc_read	= seq_read,
 	.proc_lseek	= seq_lseek,
 	.proc_release	= single_release,
 	.proc_write	= sysemu_proc_write,
 };

 int __init make_proc_sysemu(void)
 {
 	struct proc_dir_entry *ent;
 	if (!sysemu_supported)
 		return 0;

 	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_ops);

 	if (ent == NULL)
 	{
 		printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 		return 0;
 	}

 	return 0;
 }

 late_initcall(make_proc_sysemu);

 int singlestepping(void * t)
 {
 	struct task_struct *task = t ? t : current;

 	if (!(task->ptrace & PT_DTRACE))
 		return 0;

 	if (task->thread.singlestep_syscall)
 		return 1;

 	return 2;
 }

 /*
  * Only x86 and x86_64 have an arch_align_stack().
  * All other arches have "#define arch_align_stack(x) (x)"
  * in their asm/exec.h
  * As this is included in UML from asm-um/system-generic.h,
  * we can use it to behave as the subarch does.
  */
 #ifndef arch_align_stack
 unsigned long arch_align_stack(unsigned long sp)
 {
 	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 		sp -= get_random_int() % 8192;
 	return sp & ~0xf;
 }
 #endif

 unsigned long get_wchan(struct task_struct *p)
 {
 	unsigned long stack_page, sp, ip;
 	bool seen_sched = 0;

 	if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 		return 0;

 	stack_page = (unsigned long) task_stack_page(p);
 	/* Bail if the process has no kernel stack for some reason */
 	if (stack_page == 0)
 		return 0;

 	sp = p->thread.switch_buf->JB_SP;
 	/*
 	 * Bail if the stack pointer is below the bottom of the kernel
 	 * stack for some reason
 	 */
 	if (sp < stack_page)
 		return 0;

 	while (sp < stack_page + THREAD_SIZE) {
 		ip = *((unsigned long *) sp);
 		if (in_sched_functions(ip))
 			/* Ignore everything until we're above the scheduler */
 			seen_sched = 1;
 		else if (kernel_text_address(ip) && seen_sched)
 			return ip;

 		sp += sizeof(unsigned long);
 	}

 	return 0;
 }

 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 {
 	int cpu = current_thread_info()->cpu;

 	return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
	* Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
	* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
	* Copyright 2003 PathScale, Inc.
	*/

	#include <linux/stddef.h>
	#include <linux/err.h>
	#include <linux/hardirq.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/personality.h>
	#include <linux/proc_fs.h>
	#include <linux/ptrace.h>
	#include <linux/random.h>
	#include <linux/slab.h>
	#include <linux/sched.h>
	#include <linux/sched/debug.h>
	#include <linux/sched/task.h>
	#include <linux/sched/task_stack.h>
	#include <linux/seq_file.h>
	#include <linux/tick.h>
	#include <linux/threads.h>
	#include <linux/tracehook.h>
	#include <asm/current.h>
	#include <asm/mmu_context.h>
	#include <linux/uaccess.h>
	#include <as-layout.h>
	#include <kern_util.h>
	#include <os.h>
	#include <skas.h>
	#include <linux/time-internal.h>

	/*
	* This is a per-cpu array. A processor only modifies its entry and it only
	* cares about its entry, so it's OK if another processor is modifying its
	* entry.
	*/
	struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };

	static inline int external_pid(void)
	{
	/* FIXME: Need to look up userspace_pid by cpu */
	return userspace_pid[0];
	}

	int pid_to_processor_id(int pid)
	{
	int i;

	for (i = 0; i < ncpus; i++) {
	if (cpu_tasks[i].pid == pid)
	return i;
	}
	return -1;
	}

	void free_stack(unsigned long stack, int order)
	{
	free_pages(stack, order);
	}

	unsigned long alloc_stack(int order, int atomic)
	{
	unsigned long page;
	gfp_t flags = GFP_KERNEL;

	if (atomic)
	flags = GFP_ATOMIC;
	page = __get_free_pages(flags, order);

	return page;
	}

	static inline void set_current(struct task_struct *task)
	{
	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
	{ external_pid(), task });
	}

	extern void arch_switch_to(struct task_struct *to);

	void __switch_to(struct task_struct from, struct task_struct *to)
	{
	to->thread.prev_sched = from;
	set_current(to);

	switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
	arch_switch_to(current);

	return current->thread.prev_sched;
	}

	void interrupt_end(void)
	{
	struct pt_regs *regs = &current->thread.regs;

	if (need_resched())
	schedule();
	if (test_thread_flag(TIF_SIGPENDING))
	do_signal(regs);
	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
	tracehook_notify_resume(regs);
	}

	int get_current_pid(void)
	{
	return task_pid_nr(current);
	}

	/*
	* This is called magically, by its address being stuffed in a jmp_buf
	* and being longjmp-d to.
	*/
	void new_thread_handler(void)
	{
	int (fn)(void ), n;
	void *arg;

	if (current->thread.prev_sched != NULL)
	schedule_tail(current->thread.prev_sched);
	current->thread.prev_sched = NULL;

	fn = current->thread.request.u.thread.proc;
	arg = current->thread.request.u.thread.arg;

	/*
	* callback returns only if the kernel thread execs a process
	*/
	n = fn(arg);
	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
	}

	/* Called magically, see new_thread_handler above */
	void fork_handler(void)
	{
	force_flush_all();

	schedule_tail(current->thread.prev_sched);

	/*
	* XXX: if interrupt_end() calls schedule, this call to
	* arch_switch_to isn't needed. We could want to apply this to
	* improve performance. -bb
	*/
	arch_switch_to(current);

	current->thread.prev_sched = NULL;

	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
	}

	int copy_thread(unsigned long clone_flags, unsigned long sp,
	unsigned long arg, struct task_struct * p, unsigned long tls)
	{
	void (*handler)(void);
	int kthread = current->flags & PF_KTHREAD;
	int ret = 0;

	p->thread = (struct thread_struct) INIT_THREAD;

	if (!kthread) {
	memcpy(&p->thread.regs.regs, current_pt_regs(),
	sizeof(p->thread.regs.regs));
	PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
	if (sp != 0)
	REGS_SP(p->thread.regs.regs.gp) = sp;

	handler = fork_handler;

	arch_copy_thread(&current->thread.arch, &p->thread.arch);
	} else {
	get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
	p->thread.request.u.thread.proc = (int ()(void ))sp;
	p->thread.request.u.thread.arg = (void *)arg;
	handler = new_thread_handler;
	}

	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);

	if (!kthread) {
	clear_flushed_tls(p);

	/*
	* Set a new TLS for the child thread?
	*/
	if (clone_flags & CLONE_SETTLS)
	ret = arch_set_tls(p, tls);
	}

	return ret;
	}

	void initial_thread_cb(void (proc)(void ), void *arg)
	{
	int save_kmalloc_ok = kmalloc_ok;

	kmalloc_ok = 0;
	initial_thread_cb_skas(proc, arg);
	kmalloc_ok = save_kmalloc_ok;
	}

	static void um_idle_sleep(void)
	{
	unsigned long long duration = UM_NSEC_PER_SEC;

	if (time_travel_mode != TT_MODE_OFF) {
	time_travel_sleep(duration);
	} else {
	os_idle_sleep(duration);
	}
	}

	void arch_cpu_idle(void)
	{
	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
	um_idle_sleep();
	local_irq_enable();
	}

	int __cant_sleep(void) {
	return in_atomic() \|\| irqs_disabled() \|\| in_interrupt();
	/* Is in_interrupt() really needed? */
	}

	int user_context(unsigned long sp)
	{
	unsigned long stack;

	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
	return stack != (unsigned long) current_thread_info();
	}

	extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;

	void do_uml_exitcalls(void)
	{
	exitcall_t *call;

	call = &__uml_exitcall_end;
	while (--call >= &__uml_exitcall_begin)
	(*call)();
	}

	char uml_strdup(const char string)
	{
	return kstrdup(string, GFP_KERNEL);
	}
	EXPORT_SYMBOL(uml_strdup);

	int copy_to_user_proc(void __user to, void from, int size)
	{
	return copy_to_user(to, from, size);
	}

	int copy_from_user_proc(void to, void __user from, int size)
	{
	return copy_from_user(to, from, size);
	}

	int clear_user_proc(void __user *buf, int size)
	{
	return clear_user(buf, size);
	}

	int cpu(void)
	{
	return current_thread_info()->cpu;
	}

	static atomic_t using_sysemu = ATOMIC_INIT(0);
	int sysemu_supported;

	void set_using_sysemu(int value)
	{
	if (value > sysemu_supported)
	return;
	atomic_set(&using_sysemu, value);
	}

	int get_using_sysemu(void)
	{
	return atomic_read(&using_sysemu);
	}

	static int sysemu_proc_show(struct seq_file m, void v)
	{
	seq_printf(m, "%d\n", get_using_sysemu());
	return 0;
	}

	static int sysemu_proc_open(struct inode inode, struct file file)
	{
	return single_open(file, sysemu_proc_show, NULL);
	}

	static ssize_t sysemu_proc_write(struct file file, const char __user buf,
	size_t count, loff_t *pos)
	{
	char tmp[2];

	if (copy_from_user(tmp, buf, 1))
	return -EFAULT;

	if (tmp[0] >= '0' && tmp[0] <= '2')
	set_using_sysemu(tmp[0] - '0');
	/* We use the first char, but pretend to write everything */
	return count;
	}

	static const struct proc_ops sysemu_proc_ops = {
	.proc_open = sysemu_proc_open,
	.proc_read = seq_read,
	.proc_lseek = seq_lseek,
	.proc_release = single_release,
	.proc_write = sysemu_proc_write,
	};

	int __init make_proc_sysemu(void)
	{
	struct proc_dir_entry *ent;
	if (!sysemu_supported)
	return 0;

	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_ops);

	if (ent == NULL)
	{
	printk(KERN_WARNING "Failed to register /proc/sysemu\n");
	return 0;
	}

	return 0;
	}

	late_initcall(make_proc_sysemu);

	int singlestepping(void * t)
	{
	struct task_struct *task = t ? t : current;

	if (!(task->ptrace & PT_DTRACE))
	return 0;

	if (task->thread.singlestep_syscall)
	return 1;

	return 2;
	}

	/*
	* Only x86 and x86_64 have an arch_align_stack().
	* All other arches have "#define arch_align_stack(x) (x)"
	* in their asm/exec.h
	* As this is included in UML from asm-um/system-generic.h,
	* we can use it to behave as the subarch does.
	*/
	#ifndef arch_align_stack
	unsigned long arch_align_stack(unsigned long sp)
	{
	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
	sp -= get_random_int() % 8192;
	return sp & ~0xf;
	}
	#endif

	unsigned long get_wchan(struct task_struct *p)
	{
	unsigned long stack_page, sp, ip;
	bool seen_sched = 0;

	if ((p == NULL) \|\| (p == current) \|\| (p->state == TASK_RUNNING))
	return 0;

	stack_page = (unsigned long) task_stack_page(p);
	/* Bail if the process has no kernel stack for some reason */
	if (stack_page == 0)
	return 0;

	sp = p->thread.switch_buf->JB_SP;
	/*
	* Bail if the stack pointer is below the bottom of the kernel
	* stack for some reason
	*/
	if (sp < stack_page)
	return 0;

	while (sp < stack_page + THREAD_SIZE) {
	ip = ((unsigned long ) sp);
	if (in_sched_functions(ip))
	/* Ignore everything until we're above the scheduler */
	seen_sched = 1;
	else if (kernel_text_address(ip) && seen_sched)
	return ip;

	sp += sizeof(unsigned long);
	}

	return 0;
	}

	int elf_core_copy_fpregs(struct task_struct t, elf_fpregset_t fpu)
	{
	int cpu = current_thread_info()->cpu;

	return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
	}