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| author |   Jeremy Fitzhardinge <jeremy@goop.org> | 2008-06-25 00:19:24 -0400 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2008-07-08 13:11:11 +0200 |
| commit | 478de5a9d691dd0c048ddce62dbec23722515636 (patch) | |
| tree | 82d165c8420571925a0d56c92316f10a436f1831 /arch/x86/kernel/process_64.c | |
| parent | x86, 64-bit: __switch_to(): move arch_leave_lazy_cpu_mode() to the right place (diff) | |
| download | linux-dev-478de5a9d691dd0c048ddce62dbec23722515636.tar.xz linux-dev-478de5a9d691dd0c048ddce62dbec23722515636.zip | |
x86: save %fs and %gs before load_TLS() and arch_leave_lazy_cpu_mode()
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>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 488eaca47bd8..db5eb963e4df 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -538,6 +538,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) *next = &next_p->thread; int cpu = smp_processor_id(); struct tss_struct *tss = &per_cpu(init_tss, cpu); + unsigned fsindex, gsindex; /* we're going to use this soon, after a few expensive things */ 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)) 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); /* @@ -575,8 +585,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) * Switch FS and GS. */ { - unsigned fsindex; - savesegment(fs, fsindex); /* segment register != 0 always requires a reload. also reload when it has changed. 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) wrmsrl(MSR_FS_BASE, next->fs); prev->fsindex = fsindex; - } - { - unsigned gsindex; - savesegment(gs, gsindex); + if (unlikely(gsindex | next->gsindex | prev->gs)) { load_gs_index(next->gsindex); if (gsindex) |