x86: add %gs accessors for x86_32

Impact: cleanup

On x86_32, %gs is handled lazily.  It's not saved and restored on
kernel entry/exit but only when necessary which usually is during task
switch but there are few other places.  Currently, it's done by
calling savesegment() and loadsegment() explicitly.  Define
get_user_gs(), set_user_gs() and task_user_gs() and use them instead.

While at it, clean up register access macros in signal.c.

This cleans up code a bit and will help future changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 4eeb5cf9720d..55ea30d2a3d6 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -158,7 +158,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
         ret = KVM86->regs32;
 
         ret->fs = current->thread.saved_fs;
-        loadsegment(gs, current->thread.saved_gs);
+        set_user_gs(ret, current->thread.saved_gs);
 
         return ret;
 }
@@ -323,7 +323,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
         info->regs32->ax = 0;
         tsk->thread.saved_sp0 = tsk->thread.sp0;
         tsk->thread.saved_fs = info->regs32->fs;
-        savesegment(gs, tsk->thread.saved_gs);
+        tsk->thread.saved_gs = get_user_gs(info->regs32);
 
         tss = &per_cpu(init_tss, get_cpu());
         tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;