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x86: add %gs accessors for x86_32

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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>
This commit is contained in:
Tejun Heo
2009-02-09 22:17:40 +09:00
committed by Ingo Molnar
parent f0d96110f9
commit d9a89a26e0
9 changed files with 41 additions and 45 deletions
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6
arch/x86/kernel/process_32.c
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@@ -131,7 +131,7 @@ void __show_regs(struct pt_regs *regs, int all)
if (user_mode_vm(regs)) {
sp = regs->sp;
ss = regs->ss & 0xffff;
savesegment(gs, gs);
gs = get_user_gs(regs);
} else {
sp = (unsigned long) (&regs->sp);
savesegment(ss, ss);
@@ -304,7 +304,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
p->thread.ip = (unsigned long) ret_from_fork;
savesegment(gs, p->thread.gs);
task_user_gs(p) = get_user_gs(regs);
tsk = current;
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
@@ -342,7 +342,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
void
start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
{
__asm__("movl %0, %%gs" : : "r"(0));
set_user_gs(regs, 0);
regs->fs = 0;
set_fs(USER_DS);
regs->ds = __USER_DS;