x86/vm86: Move vm86 fields out of 'thread_struct'

Allocate a separate structure for the vm86 fields.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438148483-11932-2-git-send-email-brgerst@gmail.com
[ Build fixes. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index befc134..9615a4e 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -6,8 +6,8 @@
 /* Forward declaration, a strange C thing */
 struct task_struct;
 struct mm_struct;
+struct vm86;
 
-#include <asm/vm86.h>
 #include <asm/math_emu.h>
 #include <asm/segment.h>
 #include <asm/types.h>
@@ -400,13 +400,9 @@ struct thread_struct {
        unsigned long           cr2;
        unsigned long           trap_nr;
        unsigned long           error_code;
-#ifdef CONFIG_X86_32
+#ifdef CONFIG_VM86
        /* Virtual 86 mode info */
-       struct vm86plus_struct __user *vm86_info;
-       unsigned long           screen_bitmap;
-       unsigned long           v86flags;
-       unsigned long           v86mask;
-       unsigned long           saved_sp0;
+       struct vm86             *vm86;
 #endif
        /* IO permissions: */
        unsigned long           *io_bitmap_ptr;
@@ -718,7 +714,6 @@ static inline void spin_lock_prefetch(const void *x)
 
 #define INIT_THREAD  {                                                   \
        .sp0                    = TOP_OF_INIT_STACK,                      \
-       .vm86_info              = NULL,                                   \
        .sysenter_cs            = __KERNEL_CS,                            \
        .io_bitmap_ptr          = NULL,                                   \
 }

diff --git a/arch/x86/include/asm/vm86.h b/arch/x86/include/asm/vm86.h
index 1d8de3f..20b43b7 100644 (file)
--- a/arch/x86/include/asm/vm86.h
+++ b/arch/x86/include/asm/vm86.h
@@ -1,7 +1,6 @@
 #ifndef _ASM_X86_VM86_H
 #define _ASM_X86_VM86_H
 
-
 #include <asm/ptrace.h>
 #include <uapi/asm/vm86.h>
 
@@ -58,6 +57,14 @@ struct kernel_vm86_struct {
  */
 };
 
+struct vm86 {
+       struct vm86plus_struct __user *vm86_info;
+       unsigned long screen_bitmap;
+       unsigned long v86flags;
+       unsigned long v86mask;
+       unsigned long saved_sp0;
+};
+
 #ifdef CONFIG_VM86
 
 void handle_vm86_fault(struct kernel_vm86_regs *, long);
@@ -67,6 +74,14 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *);
 struct task_struct;
 void release_vm86_irqs(struct task_struct *);
 
+#define free_vm86(t) do {                              \
+       struct thread_struct *__t = (t);                \
+       if (__t->vm86 != NULL) {                        \
+               kfree(__t->vm86);                       \
+               __t->vm86 = NULL;                       \
+       }                                               \
+} while (0)
+
 #else
 
 #define handle_vm86_fault(a, b)
@@ -77,6 +92,8 @@ static inline int handle_vm86_trap(struct kernel_vm86_regs *a, long b, int c)
        return 0;
 }
 
+#define free_vm86(t) do { } while(0)
+
 #endif /* CONFIG_VM86 */
 
 #endif /* _ASM_X86_VM86_H */

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 397688b..2199d9b 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -29,6 +29,7 @@
 #include <asm/debugreg.h>
 #include <asm/nmi.h>
 #include <asm/tlbflush.h>
+#include <asm/vm86.h>
 
 /*
  * per-CPU TSS segments. Threads are completely 'soft' on Linux,
@@ -110,6 +111,8 @@ void exit_thread(void)
                kfree(bp);
        }
 
+       free_vm86(t);
+
        fpu__drop(fpu);
 }
 

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index e6c2b47..bfa59b1 100644 (file)
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -44,6 +44,7 @@
 #include <linux/ptrace.h>
 #include <linux/audit.h>
 #include <linux/stddef.h>
+#include <linux/slab.h>
 
 #include <asm/uaccess.h>
 #include <asm/io.h>
@@ -81,8 +82,8 @@
 /*
  * virtual flags (16 and 32-bit versions)
  */
-#define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
-#define VEFLAGS        (current->thread.v86flags)
+#define VFLAGS (*(unsigned short *)&(current->thread.vm86->v86flags))
+#define VEFLAGS        (current->thread.vm86->v86flags)
 
 #define set_flags(X, new, mask) \
 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
@@ -96,6 +97,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
        struct pt_regs *ret;
        struct task_struct *tsk = current;
        struct vm86plus_struct __user *user;
+       struct vm86 *vm86 = current->thread.vm86;
        long err = 0;
 
        /*
@@ -105,12 +107,12 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
         */
        local_irq_enable();
 
-       if (!tsk->thread.vm86_info) {
+       if (!vm86 || !vm86->vm86_info) {
                pr_alert("no vm86_info: BAD\n");
                do_exit(SIGSEGV);
        }
-       set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | tsk->thread.v86mask);
-       user = tsk->thread.vm86_info;
+       set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->v86mask);
+       user = vm86->vm86_info;
 
        if (!access_ok(VERIFY_WRITE, user, VMPI.is_vm86pus ?
                       sizeof(struct vm86plus_struct) :
@@ -137,7 +139,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
                put_user_ex(regs->fs, &user->regs.fs);
                put_user_ex(regs->gs, &user->regs.gs);
 
-               put_user_ex(tsk->thread.screen_bitmap, &user->screen_bitmap);
+               put_user_ex(vm86->screen_bitmap, &user->screen_bitmap);
        } put_user_catch(err);
        if (err) {
                pr_alert("could not access userspace vm86_info\n");
@@ -145,10 +147,10 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
        }
 
        tss = &per_cpu(cpu_tss, get_cpu());
-       tsk->thread.sp0 = tsk->thread.saved_sp0;
+       tsk->thread.sp0 = vm86->saved_sp0;
        tsk->thread.sysenter_cs = __KERNEL_CS;
        load_sp0(tss, &tsk->thread);
-       tsk->thread.saved_sp0 = 0;
+       vm86->saved_sp0 = 0;
        put_cpu();
 
        ret = KVM86->regs32;
@@ -242,9 +244,15 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
 {
        struct tss_struct *tss;
        struct task_struct *tsk = current;
+       struct vm86 *vm86 = tsk->thread.vm86;
        unsigned long err = 0;
 
-       if (tsk->thread.saved_sp0)
+       if (!vm86) {
+               if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL)))
+                       return -ENOMEM;
+               tsk->thread.vm86 = vm86;
+       }
+       if (vm86->saved_sp0)
                return -EPERM;
 
        if (!access_ok(VERIFY_READ, v86, plus ?
@@ -295,7 +303,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
        }
 
        info->regs32 = current_pt_regs();
-       tsk->thread.vm86_info = v86;
+       vm86->vm86_info = v86;
 
 /*
  * The flags register is also special: we cannot trust that the user
@@ -311,16 +319,16 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
 
        switch (info->cpu_type) {
        case CPU_286:
-               tsk->thread.v86mask = 0;
+               vm86->v86mask = 0;
                break;
        case CPU_386:
-               tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
+               vm86->v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
                break;
        case CPU_486:
-               tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
+               vm86->v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
                break;
        default:
-               tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
+               vm86->v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
                break;
        }
 
@@ -328,7 +336,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
  * Save old state, set default return value (%ax) to 0 (VM86_SIGNAL)
  */
        info->regs32->ax = VM86_SIGNAL;
-       tsk->thread.saved_sp0 = tsk->thread.sp0;
+       vm86->saved_sp0 = tsk->thread.sp0;
        lazy_save_gs(info->regs32->gs);
 
        tss = &per_cpu(cpu_tss, get_cpu());
@@ -338,7 +346,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
        load_sp0(tss, &tsk->thread);
        put_cpu();
 
-       tsk->thread.screen_bitmap = info->screen_bitmap;
+       vm86->screen_bitmap = info->screen_bitmap;
        if (info->flags & VM86_SCREEN_BITMAP)
                mark_screen_rdonly(tsk->mm);
 
@@ -408,7 +416,7 @@ static inline void clear_AC(struct kernel_vm86_regs *regs)
 
 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
 {
-       set_flags(VEFLAGS, flags, current->thread.v86mask);
+       set_flags(VEFLAGS, flags, current->thread.vm86->v86mask);
        set_flags(regs->pt.flags, flags, SAFE_MASK);
        if (flags & X86_EFLAGS_IF)
                set_IF(regs);
@@ -418,7 +426,7 @@ static inline void set_vflags_long(unsigned long flags, 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(VFLAGS, flags, current->thread.vm86->v86mask);
        set_flags(regs->pt.flags, flags, SAFE_MASK);
        if (flags & X86_EFLAGS_IF)
                set_IF(regs);
@@ -433,7 +441,7 @@ static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
        if (VEFLAGS & X86_EFLAGS_VIF)
                flags |= X86_EFLAGS_IF;
        flags |= X86_EFLAGS_IOPL;
-       return flags | (VEFLAGS & current->thread.v86mask);
+       return flags | (VEFLAGS & current->thread.vm86->v86mask);
 }
 
 static inline int is_revectored(int nr, struct revectored_struct *bitmap)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9dc9098..34a368d 100644 (file)
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -301,14 +301,16 @@ static inline void
 check_v8086_mode(struct pt_regs *regs, unsigned long address,
                 struct task_struct *tsk)
 {
+#ifdef CONFIG_VM86
        unsigned long bit;
 
-       if (!v8086_mode(regs))
+       if (!v8086_mode(regs) || !tsk->thread.vm86)
                return;
 
        bit = (address - 0xA0000) >> PAGE_SHIFT;
        if (bit < 32)
-               tsk->thread.screen_bitmap |= 1 << bit;
+               tsk->thread.vm86->screen_bitmap |= 1 << bit;
+#endif
 }
 
 static bool low_pfn(unsigned long pfn)