x86/entry/vm86: Clean up saved_fs/gs

There is no need to save FS and non-lazy GS outside the 32-bit
regs.  Lazy GS still needs to be saved because it wasn't saved
on syscall entry.  Save it in the gs slot of regs32, which is
present but unused.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.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/1437354550-25858-2-git-send-email-brgerst@gmail.com
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 43e6519df0d507429a9533b51c7a28f2c0f3b90b..f4e4e3ff753c0142be70e8701e0ff9cbad29fd8f 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -410,8 +410,6 @@ struct thread_struct {
        unsigned long           v86flags;
        unsigned long           v86mask;
        unsigned long           saved_sp0;
-       unsigned int            saved_fs;
-       unsigned int            saved_gs;
 #endif
        /* IO permissions: */
        unsigned long           *io_bitmap_ptr;

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index fc9db6ef2a95937b1abd4f37f3a466043ba818d4..761a2f9039a37109a4b9b9d411db1942c1f886c4 100644 (file)
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -159,8 +159,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
 
        ret = KVM86->regs32;
 
-       ret->fs = current->thread.saved_fs;
-       set_user_gs(ret, current->thread.saved_gs);
+       lazy_load_gs(ret->gs);
 
        return ret;
 }
@@ -315,8 +314,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
  */
        info->regs32->ax = VM86_SIGNAL;
        tsk->thread.saved_sp0 = tsk->thread.sp0;
-       tsk->thread.saved_fs = info->regs32->fs;
-       tsk->thread.saved_gs = get_user_gs(info->regs32);
+       lazy_save_gs(info->regs32->gs);
 
        tss = &per_cpu(cpu_tss, get_cpu());
        tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;