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
|
/*
* 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 <asm/errno.h>
#include <asm/percpu.h>
#include <asm/processor-flags.h>
#include <asm/segment.h>
#include <xen/interface/xen.h>
#include "xen-asm.h"
ENTRY(xen_adjust_exception_frame)
mov 8+0(%rsp), %rcx
mov 8+8(%rsp), %r11
ret $16
hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
/*
* Xen64 iret frame:
*
* ss
* rsp
* rflags
* cs
* rip <-- standard iret frame
*
* flags
*
* rcx }
* r11 }<-- pushed by hypercall page
* rsp->rax }
*/
ENTRY(xen_iret)
pushq $0
1: jmp hypercall_iret
ENDPATCH(xen_iret)
RELOC(xen_iret, 1b+1)
ENTRY(xen_sysret64)
/*
* We're already on the usermode stack at this point, but
* still with the kernel gs, so we can easily switch back
*/
movq %rsp, PER_CPU_VAR(rsp_scratch)
movq PER_CPU_VAR(kernel_stack), %rsp
pushq $__USER_DS
pushq PER_CPU_VAR(rsp_scratch)
pushq %r11
pushq $__USER_CS
pushq %rcx
pushq $VGCF_in_syscall
1: jmp hypercall_iret
ENDPATCH(xen_sysret64)
RELOC(xen_sysret64, 1b+1)
ENTRY(xen_sysret32)
/*
* We're already on the usermode stack at this point, but
* still with the kernel gs, so we can easily switch back
*/
movq %rsp, PER_CPU_VAR(rsp_scratch)
movq PER_CPU_VAR(kernel_stack), %rsp
pushq $__USER32_DS
pushq PER_CPU_VAR(rsp_scratch)
pushq %r11
pushq $__USER32_CS
pushq %rcx
pushq $0
1: jmp hypercall_iret
ENDPATCH(xen_sysret32)
RELOC(xen_sysret32, 1b+1)
/*
* Xen handles syscall callbacks much like ordinary exceptions, which
* means we have:
* - kernel gs
* - kernel rsp
* - an iret-like stack frame on the stack (including rcx and r11):
* ss
* rsp
* rflags
* cs
* rip
* r11
* rsp->rcx
*
* In all the entrypoints, we undo all that to make it look like a
* CPU-generated syscall/sysenter and jump to the normal entrypoint.
*/
.macro undo_xen_syscall
mov 0*8(%rsp), %rcx
mov 1*8(%rsp), %r11
mov 5*8(%rsp), %rsp
.endm
/* Normal 64-bit system call target */
ENTRY(xen_syscall_target)
undo_xen_syscall
jmp system_call_after_swapgs
ENDPROC(xen_syscall_target)
#ifdef CONFIG_IA32_EMULATION
/* 32-bit compat syscall target */
ENTRY(xen_syscall32_target)
undo_xen_syscall
jmp ia32_cstar_target
ENDPROC(xen_syscall32_target)
/* 32-bit compat sysenter target */
ENTRY(xen_sysenter_target)
undo_xen_syscall
jmp ia32_sysenter_target
ENDPROC(xen_sysenter_target)
#else /* !CONFIG_IA32_EMULATION */
ENTRY(xen_syscall32_target)
ENTRY(xen_sysenter_target)
lea 16(%rsp), %rsp /* strip %rcx, %r11 */
mov $-ENOSYS, %rax
pushq $0
jmp hypercall_iret
ENDPROC(xen_syscall32_target)
ENDPROC(xen_sysenter_target)
#endif /* CONFIG_IA32_EMULATION */
|
