litmus-rt.git - The LITMUS^RT kernel.

/*P:200 This contains all the /dev/lguest code, whereby the userspace
 * launcher controls and communicates with the Guest.  For example,
 * the first write will tell us the Guest's memory layout and entry
 * point.  A read will run the Guest until something happens, such as
 * a signal or the Guest accessing a device.
:*/
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/export.h>
#include "lg.h"

/*L:052
  The Launcher can get the registers, and also set some of them.
*/
static int getreg_setup(struct lg_cpu *cpu, const unsigned long __user *input)
{
	unsigned long which;

	/* We re-use the ptrace structure to specify which register to read. */
	if (get_user(which, input) != 0)
		return -EFAULT;

	/*
	 * We set up the cpu register pointer, and their next read will
	 * actually get the value (instead of running the guest).
	 *
	 * The last argument 'true' says we can access any register.
	 */
	cpu->reg_read = lguest_arch_regptr(cpu, which, true);
	if (!cpu->reg_read)
		return -ENOENT;

	/* And because this is a write() call, we return the length used. */
	return sizeof(unsigned long) * 2;
}

static int setreg(struct lg_cpu *cpu, const unsigned long __user *input)
{
	unsigned long which, value, *reg;

	/* We re-use the ptrace structure to specify which register to read. */
	if (get_user(which, input) != 0)
		return -EFAULT;
	input++;
	if (get_user(value, input) != 0)
		return -EFAULT;

	/* The last argument 'false' means we can't access all registers. */
	reg = lguest_arch_regptr(cpu, which, false);
	if (!reg)
		return -ENOENT;

	*reg = value;

	/* And because this is a write() call, we return the length used. */
	return sizeof(unsigned long) * 3;
}

/*L:050
 * Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
 * number to /dev/lguest.
 */
static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
{
	unsigned long irq;

	if (get_user(irq, input) != 0)
		return -EFAULT;
	if (irq >= LGUEST_IRQS)
		return -EINVAL;

	/*
	 * Next time the Guest runs, the core code will see if it can deliver
	 * this interrupt.
	 */
	set_interrupt(cpu, irq);
	return 0;
}

/*L:053
 * Deliver a trap: this is used by the Launcher if it can't emulate
 * an instruction.
 */
static int trap(struct lg_cpu *cpu, const unsigned long __user *input)
{
	unsigned long trapnum;

	if (get_user(trapnum, input) != 0)
		return -EFAULT;

	if (!deliver_trap(cpu, trapnum))
		return -EINVAL;

	return 0;
}

/*L:040
 * Once our Guest is initialized, the Launcher makes it run by reading
 * from /dev/lguest.
 */
static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
{
	struct lguest *lg = file->private_data;
	struct lg_cpu *cpu;
	unsigned int cpu_id = *o;


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