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Commit 49d26b6e authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Andi Kleen
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[PATCH] i386: Update sys_vm86 to cope with changed pt_regs and %gs usage 



sys_vm86 uses a struct kernel_vm86_regs, which is identical to pt_regs, but
adds an extra space for all the segment registers.  Previously this structure
was completely independent, so changes in pt_regs had to be reflected in
kernel_vm86_regs.  This changes just embeds pt_regs in kernel_vm86_regs, and
makes the appropriate changes to vm86.c to deal with the new naming.

Also, since %gs is dealt with differently in the kernel, this change adjusts
vm86.c to reflect this.

While making these changes, I also cleaned up some frankly bizarre code which
was added when auditing was added to sys_vm86.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
parent 66e10a44

arch/i386/kernel/vm86.c

+74 −47
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <linux/highmem.h>

#include <linux/ptrace.h>

#include <linux/audit.h>

#include <linux/stddef.h>



#include <asm/uaccess.h>

#include <asm/io.h>
@@ -72,10 +73,10 @@ 
/*

 * 8- and 16-bit register defines..

 */

#define AL(regs)	(((unsigned char *)&((regs)->eax))[0])

#define AH(regs)	(((unsigned char *)&((regs)->eax))[1])

#define IP(regs)	(*(unsigned short *)&((regs)->eip))

#define SP(regs)	(*(unsigned short *)&((regs)->esp))

#define AL(regs)	(((unsigned char *)&((regs)->pt.eax))[0])

#define AH(regs)	(((unsigned char *)&((regs)->pt.eax))[1])

#define IP(regs)	(*(unsigned short *)&((regs)->pt.eip))

#define SP(regs)	(*(unsigned short *)&((regs)->pt.esp))



/*

 * virtual flags (16 and 32-bit versions)
@@ -89,10 +90,37 @@ 
#define SAFE_MASK	(0xDD5)

#define RETURN_MASK	(0xDFF)



#define VM86_REGS_PART2 orig_eax

#define VM86_REGS_SIZE1 \

        ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )

#define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)

/* convert kernel_vm86_regs to vm86_regs */

static int copy_vm86_regs_to_user(struct vm86_regs __user *user,

				  const struct kernel_vm86_regs *regs)

{

	int ret = 0;



	/* kernel_vm86_regs is missing xfs, so copy everything up to

	   (but not including) xgs, and then rest after xgs. */

	ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.xgs));

	ret += copy_to_user(&user->__null_gs, &regs->pt.xgs,

			    sizeof(struct kernel_vm86_regs) -

			    offsetof(struct kernel_vm86_regs, pt.xgs));



	return ret;

}



/* convert vm86_regs to kernel_vm86_regs */

static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs,

				    const struct vm86_regs __user *user,

				    unsigned extra)

{

	int ret = 0;



	ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.xgs));

	ret += copy_from_user(&regs->pt.xgs, &user->__null_gs,

			      sizeof(struct kernel_vm86_regs) -

			      offsetof(struct kernel_vm86_regs, pt.xgs) +

			      extra);



	return ret;

}



struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));

struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
@@ -112,10 +140,8 @@ struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs) 
		printk("no vm86_info: BAD\n");

		do_exit(SIGSEGV);

	}

	set_flags(regs->eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);

	tmp = copy_to_user(&current->thread.vm86_info->regs,regs, VM86_REGS_SIZE1);

	tmp += copy_to_user(&current->thread.vm86_info->regs.VM86_REGS_PART2,

		&regs->VM86_REGS_PART2, VM86_REGS_SIZE2);

	set_flags(regs->pt.eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);

	tmp = copy_vm86_regs_to_user(&current->thread.vm86_info->regs,regs);

	tmp += put_user(current->thread.screen_bitmap,&current->thread.vm86_info->screen_bitmap);

	if (tmp) {

		printk("vm86: could not access userspace vm86_info\n");
@@ -129,9 +155,11 @@ struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs) 
	current->thread.saved_esp0 = 0;

	put_cpu();



	loadsegment(fs, current->thread.saved_fs);

	loadsegment(gs, current->thread.saved_gs);

	ret = KVM86->regs32;



	loadsegment(fs, current->thread.saved_fs);

	ret->xgs = current->thread.saved_gs;



	return ret;

}
@@ -183,9 +211,9 @@ asmlinkage int sys_vm86old(struct pt_regs regs) 
	tsk = current;

	if (tsk->thread.saved_esp0)

		goto out;

	tmp  = copy_from_user(&info, v86, VM86_REGS_SIZE1);

	tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,

		(long)&info.vm86plus - (long)&info.regs.VM86_REGS_PART2);

	tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,

				       offsetof(struct kernel_vm86_struct, vm86plus) -

				       sizeof(info.regs));

	ret = -EFAULT;

	if (tmp)

		goto out;
@@ -233,9 +261,9 @@ asmlinkage int sys_vm86(struct pt_regs regs) 
	if (tsk->thread.saved_esp0)

		goto out;

	v86 = (struct vm86plus_struct __user *)regs.ecx;

	tmp  = copy_from_user(&info, v86, VM86_REGS_SIZE1);

	tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,

		(long)&info.regs32 - (long)&info.regs.VM86_REGS_PART2);

	tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,

				       offsetof(struct kernel_vm86_struct, regs32) -

				       sizeof(info.regs));

	ret = -EFAULT;

	if (tmp)

		goto out;
@@ -252,15 +280,15 @@ asmlinkage int sys_vm86(struct pt_regs regs) 
static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)

{

	struct tss_struct *tss;

	long eax;

/*

 * make sure the vm86() system call doesn't try to do anything silly

 */

	info->regs.__null_ds = 0;

	info->regs.__null_es = 0;

	info->regs.pt.xds = 0;

	info->regs.pt.xes = 0;

	info->regs.pt.xgs = 0;



/* we are clearing fs,gs later just before "jmp resume_userspace",

 * because starting with Linux 2.1.x they aren't no longer saved/restored

/* we are clearing fs later just before "jmp resume_userspace",

 * because it is not saved/restored.

 */



/*
@@ -268,10 +296,10 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk 
 * has set it up safely, so this makes sure interrupt etc flags are

 * inherited from protected mode.

 */

 	VEFLAGS = info->regs.eflags;

	info->regs.eflags &= SAFE_MASK;

	info->regs.eflags |= info->regs32->eflags & ~SAFE_MASK;

	info->regs.eflags |= VM_MASK;

 	VEFLAGS = info->regs.pt.eflags;

	info->regs.pt.eflags &= SAFE_MASK;

	info->regs.pt.eflags |= info->regs32->eflags & ~SAFE_MASK;

	info->regs.pt.eflags |= VM_MASK;



	switch (info->cpu_type) {

		case CPU_286:
@@ -294,7 +322,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk 
	info->regs32->eax = 0;

	tsk->thread.saved_esp0 = tsk->thread.esp0;

	savesegment(fs, tsk->thread.saved_fs);

	savesegment(gs, tsk->thread.saved_gs);

	tsk->thread.saved_gs = info->regs32->xgs;



	tss = &per_cpu(init_tss, get_cpu());

	tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
@@ -306,19 +334,18 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk 
	tsk->thread.screen_bitmap = info->screen_bitmap;

	if (info->flags & VM86_SCREEN_BITMAP)

		mark_screen_rdonly(tsk->mm);

	__asm__ __volatile__("xorl %eax,%eax; movl %eax,%fs; movl %eax,%gs\n\t");

	__asm__ __volatile__("movl %%eax, %0\n" :"=r"(eax));



	/*call audit_syscall_exit since we do not exit via the normal paths */

	if (unlikely(current->audit_context))

		audit_syscall_exit(AUDITSC_RESULT(eax), eax);

		audit_syscall_exit(AUDITSC_RESULT(0), 0);



	__asm__ __volatile__(

		"movl %0,%%esp\n\t"

		"movl %1,%%ebp\n\t"

		"mov  %2, %%fs\n\t"

		"jmp resume_userspace"

		: /* no outputs */

		:"r" (&info->regs), "r" (task_thread_info(tsk)));

		:"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));

	/* we never return here */

}
@@ -348,12 +375,12 @@ static inline void clear_IF(struct kernel_vm86_regs * regs) 


static inline void clear_TF(struct kernel_vm86_regs * regs)

{

	regs->eflags &= ~TF_MASK;

	regs->pt.eflags &= ~TF_MASK;

}



static inline void clear_AC(struct kernel_vm86_regs * regs)

{

	regs->eflags &= ~AC_MASK;

	regs->pt.eflags &= ~AC_MASK;

}



/* It is correct to call set_IF(regs) from the set_vflags_*
@@ -370,7 +397,7 @@ static inline void clear_AC(struct kernel_vm86_regs * regs) 
static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)

{

	set_flags(VEFLAGS, eflags, current->thread.v86mask);

	set_flags(regs->eflags, eflags, SAFE_MASK);

	set_flags(regs->pt.eflags, eflags, SAFE_MASK);

	if (eflags & IF_MASK)

		set_IF(regs);

	else
@@ -380,7 +407,7 @@ static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs 
static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)

{

	set_flags(VFLAGS, flags, current->thread.v86mask);

	set_flags(regs->eflags, flags, SAFE_MASK);

	set_flags(regs->pt.eflags, flags, SAFE_MASK);

	if (flags & IF_MASK)

		set_IF(regs);

	else
@@ -389,7 +416,7 @@ static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_reg 


static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)

{

	unsigned long flags = regs->eflags & RETURN_MASK;

	unsigned long flags = regs->pt.eflags & RETURN_MASK;



	if (VEFLAGS & VIF_MASK)

		flags |= IF_MASK;
@@ -493,7 +520,7 @@ static void do_int(struct kernel_vm86_regs *regs, int i, 
	unsigned long __user *intr_ptr;

	unsigned long segoffs;



	if (regs->cs == BIOSSEG)

	if (regs->pt.xcs == BIOSSEG)

		goto cannot_handle;

	if (is_revectored(i, &KVM86->int_revectored))

		goto cannot_handle;
@@ -505,9 +532,9 @@ static void do_int(struct kernel_vm86_regs *regs, int i, 
	if ((segoffs >> 16) == BIOSSEG)

		goto cannot_handle;

	pushw(ssp, sp, get_vflags(regs), cannot_handle);

	pushw(ssp, sp, regs->cs, cannot_handle);

	pushw(ssp, sp, regs->pt.xcs, cannot_handle);

	pushw(ssp, sp, IP(regs), cannot_handle);

	regs->cs = segoffs >> 16;

	regs->pt.xcs = segoffs >> 16;

	SP(regs) -= 6;

	IP(regs) = segoffs & 0xffff;

	clear_TF(regs);
@@ -524,7 +551,7 @@ int handle_vm86_trap(struct kernel_vm86_regs * regs, long error_code, int trapno 
	if (VMPI.is_vm86pus) {

		if ( (trapno==3) || (trapno==1) )

			return_to_32bit(regs, VM86_TRAP + (trapno << 8));

		do_int(regs, trapno, (unsigned char __user *) (regs->ss << 4), SP(regs));

		do_int(regs, trapno, (unsigned char __user *) (regs->pt.xss << 4), SP(regs));

		return 0;

	}

	if (trapno !=1)
@@ -560,10 +587,10 @@ void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code) 
		handle_vm86_trap(regs, 0, 1); \

	return; } while (0)



	orig_flags = *(unsigned short *)&regs->eflags;

	orig_flags = *(unsigned short *)&regs->pt.eflags;



	csp = (unsigned char __user *) (regs->cs << 4);

	ssp = (unsigned char __user *) (regs->ss << 4);

	csp = (unsigned char __user *) (regs->pt.xcs << 4);

	ssp = (unsigned char __user *) (regs->pt.xss << 4);

	sp = SP(regs);

	ip = IP(regs);
@@ -650,7 +677,7 @@ void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code) 
			SP(regs) += 6;

		}

		IP(regs) = newip;

		regs->cs = newcs;

		regs->pt.xcs = newcs;

		CHECK_IF_IN_TRAP;

		if (data32) {

			set_vflags_long(newflags, regs);

include/asm-i386/vm86.h

+2 −15
Original line number Diff line number Diff line
@@ -145,26 +145,13 @@ struct vm86plus_struct { 
 * at the end of the structure. Look at ptrace.h to see the "normal"

 * setup. For user space layout see 'struct vm86_regs' above.

 */

#include <asm/ptrace.h>



struct kernel_vm86_regs {

/*

 * normal regs, with special meaning for the segment descriptors..

 */

	long ebx;

	long ecx;

	long edx;

	long esi;

	long edi;

	long ebp;

	long eax;

	long __null_ds;

	long __null_es;

	long orig_eax;

	long eip;

	unsigned short cs, __csh;

	long eflags;

	long esp;

	unsigned short ss, __ssh;

	struct pt_regs pt;

/*

 * these are specific to v86 mode:

 */