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1/*
2 * Asm versions of Xen pv-ops, suitable for either direct use or
3 * inlining. The inline versions are the same as the direct-use
4 * versions, with the pre- and post-amble chopped off.
5 *
6 * This code is encoded for size rather than absolute efficiency, with
7 * a view to being able to inline as much as possible.
8 *
9 * We only bother with direct forms (ie, vcpu in percpu data) of the
10 * operations here; the indirect forms are better handled in C, since
11 * they're generally too large to inline anyway.
12 */
13
14#include <asm/asm-offsets.h>
15#include <asm/percpu.h>
16#include <asm/processor-flags.h>
17
18#include "xen-asm.h"
19
20/*
21 * Enable events. This clears the event mask and tests the pending
22 * event status with one and operation. If there are pending events,
23 * then enter the hypervisor to get them handled.
24 */
25ENTRY(xen_irq_enable_direct)
26 /* Unmask events */
27 movb $0, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
28
29 /*
30 * Preempt here doesn't matter because that will deal with any
31 * pending interrupts. The pending check may end up being run
32 * on the wrong CPU, but that doesn't hurt.
33 */
34
35 /* Test for pending */
36 testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
37 jz 1f
38
392: call check_events
401:
41ENDPATCH(xen_irq_enable_direct)
42 ret
43 ENDPROC(xen_irq_enable_direct)
44 RELOC(xen_irq_enable_direct, 2b+1)
45
46
47/*
48 * Disabling events is simply a matter of making the event mask
49 * non-zero.
50 */
51ENTRY(xen_irq_disable_direct)
52 movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
53ENDPATCH(xen_irq_disable_direct)
54 ret
55 ENDPROC(xen_irq_disable_direct)
56 RELOC(xen_irq_disable_direct, 0)
57
58/*
59 * (xen_)save_fl is used to get the current interrupt enable status.
60 * Callers expect the status to be in X86_EFLAGS_IF, and other bits
61 * may be set in the return value. We take advantage of this by
62 * making sure that X86_EFLAGS_IF has the right value (and other bits
63 * in that byte are 0), but other bits in the return value are
64 * undefined. We need to toggle the state of the bit, because Xen and
65 * x86 use opposite senses (mask vs enable).
66 */
67ENTRY(xen_save_fl_direct)
68 testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
69 setz %ah
70 addb %ah, %ah
71ENDPATCH(xen_save_fl_direct)
72 ret
73 ENDPROC(xen_save_fl_direct)
74 RELOC(xen_save_fl_direct, 0)
75
76
77/*
78 * In principle the caller should be passing us a value return from
79 * xen_save_fl_direct, but for robustness sake we test only the
80 * X86_EFLAGS_IF flag rather than the whole byte. After setting the
81 * interrupt mask state, it checks for unmasked pending events and
82 * enters the hypervisor to get them delivered if so.
83 */
84ENTRY(xen_restore_fl_direct)
85#ifdef CONFIG_X86_64
86 testw $X86_EFLAGS_IF, %di
87#else
88 testb $X86_EFLAGS_IF>>8, %ah
89#endif
90 setz PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
91 /*
92 * Preempt here doesn't matter because that will deal with any
93 * pending interrupts. The pending check may end up being run
94 * on the wrong CPU, but that doesn't hurt.
95 */
96
97 /* check for unmasked and pending */
98 cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
99 jz 1f
1002: call check_events
1011:
102ENDPATCH(xen_restore_fl_direct)
103 ret
104 ENDPROC(xen_restore_fl_direct)
105 RELOC(xen_restore_fl_direct, 2b+1)
106
107
108/*
109 * Force an event check by making a hypercall, but preserve regs
110 * before making the call.
111 */
112check_events:
113#ifdef CONFIG_X86_32
114 push %eax
115 push %ecx
116 push %edx
117 call xen_force_evtchn_callback
118 pop %edx
119 pop %ecx
120 pop %eax
121#else
122 push %rax
123 push %rcx
124 push %rdx
125 push %rsi
126 push %rdi
127 push %r8
128 push %r9
129 push %r10
130 push %r11
131 call xen_force_evtchn_callback
132 pop %r11
133 pop %r10
134 pop %r9
135 pop %r8
136 pop %rdi
137 pop %rsi
138 pop %rdx
139 pop %rcx
140 pop %rax
141#endif
142 ret