Commit 18c13737 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: add operations to get/set a register from the Launcher. 



We use the ptrace API struct, and we currently don't let them set
anything but the normal registers (we'd have to filter the others).

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent a454bb36

drivers/lguest/core.c

+8 −0
Original line number Diff line number Diff line
@@ -208,6 +208,14 @@ void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b, 
 */

int run_guest(struct lg_cpu *cpu, unsigned long __user *user)

{

	/* If the launcher asked for a register with LHREQ_GETREG */

	if (cpu->reg_read) {

		if (put_user(*cpu->reg_read, user))

			return -EFAULT;

		cpu->reg_read = NULL;

		return sizeof(*cpu->reg_read);

	}



	/* We stop running once the Guest is dead. */

	while (!cpu->lg->dead) {

		unsigned int irq;

drivers/lguest/lg.h

+3 −0
Original line number Diff line number Diff line
@@ -52,6 +52,8 @@ struct lg_cpu { 


	unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */



	unsigned long *reg_read; /* register from LHREQ_GETREG */



	/* At end of a page shared mapped over lguest_pages in guest. */

	unsigned long regs_page;

	struct lguest_regs *regs;
@@ -210,6 +212,7 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu); 
int lguest_arch_init_hypercalls(struct lg_cpu *cpu);

int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args);

void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start);

unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any);



/* <arch>/switcher.S: */

extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];

drivers/lguest/lguest_user.c

+49 −0
Original line number Diff line number Diff line
@@ -173,6 +173,51 @@ static int attach_eventfd(struct lguest *lg, const unsigned long __user *input) 
	return err;

}



/* 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.
@@ -434,6 +479,10 @@ static ssize_t write(struct file *file, const char __user *in, 
		return user_send_irq(cpu, input);

	case LHREQ_EVENTFD:

		return attach_eventfd(lg, input);

	case LHREQ_GETREG:

		return getreg_setup(cpu, input);

	case LHREQ_SETREG:

		return setreg(cpu, input);

	default:

		return -EINVAL;

	}

drivers/lguest/x86/core.c

+46 −0
Original line number Diff line number Diff line
@@ -181,6 +181,52 @@ static void run_guest_once(struct lg_cpu *cpu, struct lguest_pages *pages) 
}

/*:*/



unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any)

{

	switch (reg_off) {

	case offsetof(struct pt_regs, bx):

		return &cpu->regs->ebx;

	case offsetof(struct pt_regs, cx):

		return &cpu->regs->ecx;

	case offsetof(struct pt_regs, dx):

		return &cpu->regs->edx;

	case offsetof(struct pt_regs, si):

		return &cpu->regs->esi;

	case offsetof(struct pt_regs, di):

		return &cpu->regs->edi;

	case offsetof(struct pt_regs, bp):

		return &cpu->regs->ebp;

	case offsetof(struct pt_regs, ax):

		return &cpu->regs->eax;

	case offsetof(struct pt_regs, ip):

		return &cpu->regs->eip;

	case offsetof(struct pt_regs, sp):

		return &cpu->regs->esp;

	}



	/* Launcher can read these, but we don't allow any setting. */

	if (any) {

		switch (reg_off) {

		case offsetof(struct pt_regs, ds):

			return &cpu->regs->ds;

		case offsetof(struct pt_regs, es):

			return &cpu->regs->es;

		case offsetof(struct pt_regs, fs):

			return &cpu->regs->fs;

		case offsetof(struct pt_regs, gs):

			return &cpu->regs->gs;

		case offsetof(struct pt_regs, cs):

			return &cpu->regs->cs;

		case offsetof(struct pt_regs, flags):

			return &cpu->regs->eflags;

		case offsetof(struct pt_regs, ss):

			return &cpu->regs->ss;

		}

	}



	return NULL;

}



/*M:002

 * There are hooks in the scheduler which we can register to tell when we

 * get kicked off the CPU (preempt_notifier_register()).  This would allow us

include/linux/lguest_launcher.h

+2 −0
Original line number Diff line number Diff line
@@ -63,6 +63,8 @@ enum lguest_req 
	LHREQ_IRQ, /* + irq */

	LHREQ_BREAK, /* No longer used */

	LHREQ_EVENTFD, /* + address, fd. */

	LHREQ_GETREG, /* + offset within struct pt_regs (then read value). */

	LHREQ_SETREG, /* + offset within struct pt_regs, value. */

};



/*