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/*
Asm versions of Xen pv-ops, suitable for either direct use or inlining.
The inline versions are the same as the direct-use versions, with the
pre- and post-amble chopped off.
This code is encoded for size rather than absolute efficiency,
with a view to being able to inline as much as possible.
We only bother with direct forms (ie, vcpu in pda) of the operations
here; the indirect forms are better handled in C, since they're
generally too large to inline anyway.
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/percpu.h>
#include <asm/asm-offsets.h>
#include <asm/processor-flags.h>
#define RELOC(x, v) .globl x##_reloc; x##_reloc=v
#define ENDPATCH(x) .globl x##_end; x##_end=.
/*
Enable events. This clears the event mask and tests the pending
event status with one and operation. If there are pending
events, then enter the hypervisor to get them handled.
*/
ENTRY(xen_irq_enable_direct)
/* Clear mask and test pending */
andw $0x00ff, PER_CPU_VAR(xen_vcpu_info)+XEN_vcpu_info_pending
/* Preempt here doesn't matter because that will deal with
any pending interrupts. The pending check may end up being
run on the wrong CPU, but that doesn't hurt. */
jz 1f
2: call check_events
1:
ENDPATCH(xen_irq_enable_direct)
ret
ENDPROC(xen_irq_enable_direct)
RELOC(xen_irq_enable_direct, 2b+1)
/*
Disabling events is simply a matter of making the event mask
non-zero.
*/
ENTRY(xen_irq_disable_direct)
movb $1, PER_CPU_VAR(xen_vcpu_info)+XEN_vcpu_info_mask
ENDPATCH(xen_irq_disable_direct)
ret
ENDPROC(xen_irq_disable_direct)
RELOC(xen_irq_disable_direct, 0)
/*
(xen_)save_fl is used to get the current interrupt enable status.
Callers expect the status to be in X86_EFLAGS_IF, and other bits
may be set in the return value. We take advantage of this by
making sure that X86_EFLAGS_IF has the right value (and other bits
in that byte are 0), but other bits in the return value are
undefined. We need to toggle the state of the bit, because
Xen and x86 use opposite senses (mask vs enable).
*/
ENTRY(xen_save_fl_direct)
testb $0xff, PER_CPU_VAR(xen_vcpu_info)+XEN_vcpu_info_mask
setz %ah
addb %ah,%ah
ENDPATCH(xen_save_fl_direct)
ret
ENDPROC(xen_save_fl_direct)
RELOC(xen_save_fl_direct, 0)
/*
In principle the caller should be passing us a value return
from xen_save_fl_direct, but for robustness sake we test only
the X86_EFLAGS_IF flag rather than the whole byte. After
setting the interrupt mask state, it checks for unmasked
pending events and enters the hypervisor to get them delivered
if so.
*/
ENTRY(xen_restore_fl_direct)
testb $X86_EFLAGS_IF>>8, %ah
setz %al
movb %al, PER_CPU_VAR(xen_vcpu_info)+XEN_vcpu_info_mask
/* Preempt here doesn't matter because that will deal with
any pending interrupts. The pending check may end up being
run on the wrong CPU, but that doesn't hurt. */
/* check for pending but unmasked */
cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info)+XEN_vcpu_info_pending
jz 1f
2: call check_events
1:
ENDPATCH(xen_restore_fl_direct)
ret
ENDPROC(xen_restore_fl_direct)
RELOC(xen_restore_fl_direct, 2b+1)
/*
Force an event check by making a hypercall,
but preserve regs before making the call.
*/
check_events:
push %eax
push %ecx
push %edx
call force_evtchn_callback
pop %edx
pop %ecx
pop %eax
ret
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