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# HG changeset patch
# User "Eduardo Habkost <ehabkost@redhat.com>"
# Date 1190317568 10800
# Node ID ab958de6e67d1b4f6c321cd46d2793d2409b91fd
# Parent 8792a16b6dd531cad0ed28d9bef86e3e597ea8db
x86_64: Fix sleazy-fpu under Xen
- Make it reset fpu_counter when needed (like __unlazy_fpu() does)
- Make it call clts() before restoring the fpu state during task switch
(clts() will still not be called during the device_not_available trap,
because it is not needed under Xen)
diff -r 8792a16b6dd5 -r ab958de6e67d arch/x86_64/kernel/entry-xen.S
--- a/arch/x86_64/kernel/entry-xen.S Thu Sep 20 15:30:16 2007 -0300
+++ b/arch/x86_64/kernel/entry-xen.S Thu Sep 20 16:46:08 2007 -0300
@@ -1071,7 +1071,9 @@ END(simd_coprocessor_error)
END(simd_coprocessor_error)
ENTRY(device_not_available)
- zeroentry math_state_restore
+ # 'clts' is done by Xen during virtual trap, so we can call
+ # __math_state_restore instead of math_state_restore
+ zeroentry __math_state_restore
END(device_not_available)
/* runs on exception stack */
diff -r 8792a16b6dd5 -r ab958de6e67d arch/x86_64/kernel/process-xen.c
--- a/arch/x86_64/kernel/process-xen.c Thu Sep 20 15:30:16 2007 -0300
+++ b/arch/x86_64/kernel/process-xen.c Thu Sep 20 16:46:08 2007 -0300
@@ -637,7 +637,8 @@ __switch_to(struct task_struct *prev_p,
if (prev_p->thread_info->status & TS_USEDFPU) {
__save_init_fpu(prev_p); /* _not_ save_init_fpu() */
HYPERVISOR_fpu_taskswitch(1);
- }
+ } else
+ prev_p->fpu_counter = 0;
/*
* Switch the PDA context.
diff -r 8792a16b6dd5 -r ab958de6e67d arch/x86_64/kernel/traps-xen.c
--- a/arch/x86_64/kernel/traps-xen.c Thu Sep 20 15:30:16 2007 -0300
+++ b/arch/x86_64/kernel/traps-xen.c Thu Sep 20 16:46:08 2007 -0300
@@ -1064,16 +1064,21 @@ asmlinkage void __attribute__((weak)) mc
* Careful.. There are problems with IBM-designed IRQ13 behaviour.
* Don't touch unless you *really* know how it works.
*/
-asmlinkage void math_state_restore(void)
+asmlinkage void __math_state_restore(void)
{
struct task_struct *me = current;
- /* clts(); */ /* 'clts' is done for us by Xen during virtual trap. */
if (!used_math())
init_fpu(me);
restore_fpu_checking(&me->thread.i387.fxsave);
task_thread_info(me)->status |= TS_USEDFPU;
me->fpu_counter++;
+}
+
+asmlinkage void math_state_restore(void)
+{
+ clts(); /* Allow maths ops (or we recurse) */
+ __math_state_restore();
}
diff -r 8792a16b6dd5 -r ab958de6e67d arch/x86_64/kernel/traps.c
--- a/arch/x86_64/kernel/traps.c Thu Sep 20 15:30:16 2007 -0300
+++ b/arch/x86_64/kernel/traps.c Thu Sep 20 16:46:08 2007 -0300
@@ -1056,16 +1056,21 @@ asmlinkage void __attribute__((weak)) mc
* Careful.. There are problems with IBM-designed IRQ13 behaviour.
* Don't touch unless you *really* know how it works.
*/
-asmlinkage void math_state_restore(void)
+asmlinkage void __math_state_restore(void)
{
struct task_struct *me = current;
- clts(); /* Allow maths ops (or we recurse) */
if (!used_math())
init_fpu(me);
restore_fpu_checking(&me->thread.i387.fxsave);
task_thread_info(me)->status |= TS_USEDFPU;
me->fpu_counter++;
+}
+
+asmlinkage void math_state_restore(void)
+{
+ clts(); /* Allow maths ops (or we recurse) */
+ __math_state_restore();
}
void __init trap_init(void)
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