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x86: save %fs and %gs before load_TLS() and arch_leave_lazy_cpu_mode()

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We must do this because load_TLS() may need to clear %fs and %gs.
(e.g. under Xen).

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge
2008-06-25 00:19:24 -04:00
committed by Ingo Molnar
parent 3fe0a63efd
commit 478de5a9d6
1 changed files with 11 additions and 6 deletions
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17
arch/x86/kernel/process_64.c
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@@ -538,6 +538,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
*next = &next_p->thread; *next = &next_p->thread;
int cpu = smp_processor_id(); int cpu = smp_processor_id();
struct tss_struct *tss = &per_cpu(init_tss, cpu); struct tss_struct *tss = &per_cpu(init_tss, cpu);
unsigned fsindex, gsindex;
/* we're going to use this soon, after a few expensive things */ /* we're going to use this soon, after a few expensive things */
if (next_p->fpu_counter>5) if (next_p->fpu_counter>5)
@@ -560,6 +561,15 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
if (unlikely(next->ds | prev->ds)) if (unlikely(next->ds | prev->ds))
loadsegment(ds, next->ds); loadsegment(ds, next->ds);
/* We must save %fs and %gs before load_TLS() because
* %fs and %gs may be cleared by load_TLS().
*
* (e.g. xen_load_tls())
*/
savesegment(fs, fsindex);
savesegment(gs, gsindex);
load_TLS(next, cpu); load_TLS(next, cpu);
/* /*
@@ -575,8 +585,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* Switch FS and GS. * Switch FS and GS.
*/ */
{ {
unsigned fsindex;
savesegment(fs, fsindex);
/* segment register != 0 always requires a reload. /* segment register != 0 always requires a reload.
also reload when it has changed. also reload when it has changed.
when prev process used 64bit base always reload when prev process used 64bit base always reload
@@ -594,10 +602,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
if (next->fs) if (next->fs)
wrmsrl(MSR_FS_BASE, next->fs); wrmsrl(MSR_FS_BASE, next->fs);
prev->fsindex = fsindex; prev->fsindex = fsindex;
}
{
unsigned gsindex;
savesegment(gs, gsindex);
if (unlikely(gsindex | next->gsindex | prev->gs)) { if (unlikely(gsindex | next->gsindex | prev->gs)) {
load_gs_index(next->gsindex); load_gs_index(next->gsindex);
if (gsindex) if (gsindex)