Allow guest to specify syscall vector to use. (c18acd73) · Commits · 戴 / test

arch/x86/lguest/boot.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -87,6 +87,7 @@ struct lguest_data lguest_data = {
		.noirq_start = (u32)lguest_noirq_start,
		.noirq_end = (u32)lguest_noirq_end,
		.blocked_interrupts = { 1 }, /* Block timer interrupts */
		.syscall_vec = SYSCALL_VECTOR,
		};
		static cycle_t clock_base;

drivers/lguest/core.c

+20 −10

Original line number	Diff line number	Diff line
		@@ -281,37 +281,47 @@ static int __init init(void)
		/* First we put the Switcher up in very high virtual memory. */
		err = map_switcher();
		if (err)
		return err;
		goto out;

		/* Now we set up the pagetable implementation for the Guests. */
		err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
		if (err) {
		unmap_switcher();
		return err;
		}
		if (err)
		goto unmap;

		/* The I/O subsystem needs some things initialized. */
		lguest_io_init();

		/* We might need to reserve an interrupt vector. */
		err = init_interrupts();
		if (err)
		goto free_pgtables;

		/* /dev/lguest needs to be registered. */
		err = lguest_device_init();
		if (err) {
		free_pagetables();
		unmap_switcher();
		return err;
		}
		if (err)
		goto free_interrupts;

		/* Finally we do some architecture-specific setup. */
		lguest_arch_host_init();

		/* All good! */
		return 0;

		free_interrupts:
		free_interrupts();
		free_pgtables:
		free_pagetables();
		unmap:
		unmap_switcher();
		out:
		return err;
		}

		/* Cleaning up is just the same code, backwards. With a little French. */
		static void __exit fini(void)
		{
		lguest_device_remove();
		free_interrupts();
		free_pagetables();
		unmap_switcher();

drivers/lguest/interrupts_and_traps.c

+48 −1

Original line number	Diff line number	Diff line
		@@ -12,8 +12,14 @@
		* them first, so we also have a way of "reflecting" them into the Guest as if
		* they had been delivered to it directly. :*/
		#include <linux/uaccess.h>
		#include <linux/interrupt.h>
		#include <linux/module.h>
		#include "lg.h"

		/* Allow Guests to use a non-128 (ie. non-Linux) syscall trap. */
		static unsigned int syscall_vector = SYSCALL_VECTOR;
		module_param(syscall_vector, uint, 0444);

		/* The address of the interrupt handler is split into two bits: */
		static unsigned long idt_address(u32 lo, u32 hi)
		{
		@@ -183,6 +189,47 @@ void maybe_do_interrupt(struct lguest *lg)
		* timer interrupt. */
		write_timestamp(lg);
		}
		/:/

		/* Linux uses trap 128 for system calls. Plan9 uses 64, and Ron Minnich sent
		* me a patch, so we support that too. It'd be a big step for lguest if half
		* the Plan 9 user base were to start using it.
		*
		* Actually now I think of it, it's possible that Ron is half the Plan 9
		* userbase. Oh well. */
		static bool could_be_syscall(unsigned int num)
		{
		/* Normal Linux SYSCALL_VECTOR or reserved vector? */
		return num == SYSCALL_VECTOR \|\| num == syscall_vector;
		}

		/* The syscall vector it wants must be unused by Host. */
		bool check_syscall_vector(struct lguest *lg)
		{
		u32 vector;

		if (get_user(vector, &lg->lguest_data->syscall_vec))
		return false;

		return could_be_syscall(vector);
		}

		int init_interrupts(void)
		{
		/* If they want some strange system call vector, reserve it now */
		if (syscall_vector != SYSCALL_VECTOR
		&& test_and_set_bit(syscall_vector, used_vectors)) {
		printk("lg: couldn't reserve syscall %u\n", syscall_vector);
		return -EBUSY;
		}
		return 0;
		}

		void free_interrupts(void)
		{
		if (syscall_vector != SYSCALL_VECTOR)
		clear_bit(syscall_vector, used_vectors);
		}

		/*H:220 Now we've got the routines to deliver interrupts, delivering traps
		* like page fault is easy. The only trick is that Intel decided that some
		@@ -224,7 +271,7 @@ static int direct_trap(unsigned int num)
		{
		/* Hardware interrupts don't go to the Guest at all (except system
		* call). */
		if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR)
		if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
		return 0;

		/* The Host needs to see page faults (for shadow paging and to save the

drivers/lguest/lg.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -141,6 +141,9 @@ void copy_traps(const struct lguest lg, struct desc_struct idt,
		const unsigned long *def);
		void guest_set_clockevent(struct lguest *lg, unsigned long delta);
		void init_clockdev(struct lguest *lg);
		bool check_syscall_vector(struct lguest *lg);
		int init_interrupts(void);
		void free_interrupts(void);

		/* segments.c: */
		void setup_default_gdt_entries(struct lguest_ro_state *state);

drivers/lguest/x86/core.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -530,6 +530,10 @@ int lguest_arch_init_hypercalls(struct lguest *lg)
		if (put_user(tsc_speed, &lg->lguest_data->tsc_khz))
		return -EFAULT;

		/* The interrupt code might not like the system call vector. */
		if (!check_syscall_vector(lg))
		kill_guest(lg, "bad syscall vector");

		return 0;
		}
		/* Now we've examined the hypercall code; our Guest can make requests. There

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