summaryrefslogtreecommitdiff
path: root/arch/x86/xen/xen-asm.S
blob: 508fe204520b19f9f67984303886d672eb94aa62 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Asm versions of Xen pv-ops, suitable for direct use.
 *
 * We only bother with direct forms (ie, vcpu in percpu data) of the
 * operations here; the indirect forms are better handled in C.
 */

#include <asm/asm-offsets.h>
#include <asm/percpu.h>
#include <asm/processor-flags.h>
#include <asm/frame.h>
#include <asm/asm.h>

#include <linux/linkage.h>

/*
 * 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.
 */
SYM_FUNC_START(xen_irq_enable_direct)
	FRAME_BEGIN
	/* Unmask events */
	movb $0, 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.
	 */

	/* Test for pending */
	testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
	jz 1f

	call check_events
1:
	FRAME_END
	ret
SYM_FUNC_END(xen_irq_enable_direct)


/*
 * Disabling events is simply a matter of making the event mask
 * non-zero.
 */
SYM_FUNC_START(xen_irq_disable_direct)
	movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
	ret
SYM_FUNC_END(xen_irq_disable_direct)

/*
 * (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).
 */
SYM_FUNC_START(xen_save_fl_direct)
	testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
	setz %ah
	addb %ah, %ah
	ret
SYM_FUNC_END(xen_save_fl_direct)


/*
 * 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.
 */
SYM_FUNC_START(xen_restore_fl_direct)
	FRAME_BEGIN
#ifdef CONFIG_X86_64
	testw $X86_EFLAGS_IF, %di
#else
	testb $X86_EFLAGS_IF>>8, %ah
#endif
	setz 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 unmasked and pending */
	cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
	jnz 1f
	call check_events
1:
	FRAME_END
	ret
SYM_FUNC_END(xen_restore_fl_direct)


/*
 * Force an event check by making a hypercall, but preserve regs
 * before making the call.
 */
SYM_FUNC_START(check_events)
	FRAME_BEGIN
#ifdef CONFIG_X86_32
	push %eax
	push %ecx
	push %edx
	call xen_force_evtchn_callback
	pop %edx
	pop %ecx
	pop %eax
#else
	push %rax
	push %rcx
	push %rdx
	push %rsi
	push %rdi
	push %r8
	push %r9
	push %r10
	push %r11
	call xen_force_evtchn_callback
	pop %r11
	pop %r10
	pop %r9
	pop %r8
	pop %rdi
	pop %rsi
	pop %rdx
	pop %rcx
	pop %rax
#endif
	FRAME_END
	ret
SYM_FUNC_END(check_events)

SYM_FUNC_START(xen_read_cr2)
	FRAME_BEGIN
	_ASM_MOV PER_CPU_VAR(xen_vcpu), %_ASM_AX
	_ASM_MOV XEN_vcpu_info_arch_cr2(%_ASM_AX), %_ASM_AX
	FRAME_END
	ret
SYM_FUNC_END(xen_read_cr2);

SYM_FUNC_START(xen_read_cr2_direct)
	FRAME_BEGIN
	_ASM_MOV PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_arch_cr2, %_ASM_AX
	FRAME_END
	ret
SYM_FUNC_END(xen_read_cr2_direct);