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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
|
/* 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/errno.h>
#include <asm/asm-offsets.h>
#include <asm/percpu.h>
#include <asm/processor-flags.h>
#include <asm/segment.h>
#include <asm/thread_info.h>
#include <asm/asm.h>
#include <asm/frame.h>
#include <asm/unwind_hints.h>
#include <xen/interface/xen.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <../entry/calling.h>
.pushsection .noinstr.text, "ax"
/*
* 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)
/*
* Force an event check by making a hypercall, but preserve regs
* before making the call.
*/
SYM_FUNC_START(check_events)
FRAME_BEGIN
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
FRAME_END
RET
SYM_FUNC_END(check_events)
/*
* 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)
/*
* (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)
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);
.popsection
.macro xen_pv_trap name
SYM_CODE_START(xen_\name)
UNWIND_HINT_EMPTY
ENDBR
pop %rcx
pop %r11
jmp \name
SYM_CODE_END(xen_\name)
_ASM_NOKPROBE(xen_\name)
.endm
xen_pv_trap asm_exc_divide_error
xen_pv_trap asm_xenpv_exc_debug
xen_pv_trap asm_exc_int3
xen_pv_trap asm_xenpv_exc_nmi
xen_pv_trap asm_exc_overflow
xen_pv_trap asm_exc_bounds
xen_pv_trap asm_exc_invalid_op
xen_pv_trap asm_exc_device_not_available
xen_pv_trap asm_xenpv_exc_double_fault
xen_pv_trap asm_exc_coproc_segment_overrun
xen_pv_trap asm_exc_invalid_tss
xen_pv_trap asm_exc_segment_not_present
xen_pv_trap asm_exc_stack_segment
xen_pv_trap asm_exc_general_protection
xen_pv_trap asm_exc_page_fault
xen_pv_trap asm_exc_spurious_interrupt_bug
xen_pv_trap asm_exc_coprocessor_error
xen_pv_trap asm_exc_alignment_check
#ifdef CONFIG_X86_KERNEL_IBT
xen_pv_trap asm_exc_control_protection
#endif
#ifdef CONFIG_X86_MCE
xen_pv_trap asm_xenpv_exc_machine_check
#endif /* CONFIG_X86_MCE */
xen_pv_trap asm_exc_simd_coprocessor_error
#ifdef CONFIG_IA32_EMULATION
xen_pv_trap entry_INT80_compat
#endif
xen_pv_trap asm_exc_xen_unknown_trap
xen_pv_trap asm_exc_xen_hypervisor_callback
__INIT
SYM_CODE_START(xen_early_idt_handler_array)
i = 0
.rept NUM_EXCEPTION_VECTORS
UNWIND_HINT_EMPTY
ENDBR
pop %rcx
pop %r11
jmp early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE
i = i + 1
.fill xen_early_idt_handler_array + i*XEN_EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
.endr
SYM_CODE_END(xen_early_idt_handler_array)
__FINIT
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 }
*/
SYM_CODE_START(xen_iret)
UNWIND_HINT_EMPTY
ANNOTATE_NOENDBR
pushq $0
jmp hypercall_iret
SYM_CODE_END(xen_iret)
/*
* XEN pv doesn't use trampoline stack, PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is
* also the kernel stack. Reusing swapgs_restore_regs_and_return_to_usermode()
* in XEN pv would cause %rsp to move up to the top of the kernel stack and
* leave the IRET frame below %rsp, which is dangerous to be corrupted if #NMI
* interrupts. And swapgs_restore_regs_and_return_to_usermode() pushing the IRET
* frame at the same address is useless.
*/
SYM_CODE_START(xenpv_restore_regs_and_return_to_usermode)
UNWIND_HINT_REGS
POP_REGS
/* stackleak_erase() can work safely on the kernel stack. */
STACKLEAK_ERASE_NOCLOBBER
addq $8, %rsp /* skip regs->orig_ax */
jmp xen_iret
SYM_CODE_END(xenpv_restore_regs_and_return_to_usermode)
/*
* 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
*/
/* Normal 64-bit system call target */
SYM_CODE_START(xen_syscall_target)
UNWIND_HINT_EMPTY
ENDBR
popq %rcx
popq %r11
/*
* Neither Xen nor the kernel really knows what the old SS and
* CS were. The kernel expects __USER_DS and __USER_CS, so
* report those values even though Xen will guess its own values.
*/
movq $__USER_DS, 4*8(%rsp)
movq $__USER_CS, 1*8(%rsp)
jmp entry_SYSCALL_64_after_hwframe
SYM_CODE_END(xen_syscall_target)
#ifdef CONFIG_IA32_EMULATION
/* 32-bit compat syscall target */
SYM_CODE_START(xen_syscall32_target)
UNWIND_HINT_EMPTY
ENDBR
popq %rcx
popq %r11
/*
* Neither Xen nor the kernel really knows what the old SS and
* CS were. The kernel expects __USER32_DS and __USER32_CS, so
* report those values even though Xen will guess its own values.
*/
movq $__USER32_DS, 4*8(%rsp)
movq $__USER32_CS, 1*8(%rsp)
jmp entry_SYSCALL_compat_after_hwframe
SYM_CODE_END(xen_syscall32_target)
/* 32-bit compat sysenter target */
SYM_CODE_START(xen_sysenter_target)
UNWIND_HINT_EMPTY
ENDBR
/*
* NB: Xen is polite and clears TF from EFLAGS for us. This means
* that we don't need to guard against single step exceptions here.
*/
popq %rcx
popq %r11
/*
* Neither Xen nor the kernel really knows what the old SS and
* CS were. The kernel expects __USER32_DS and __USER32_CS, so
* report those values even though Xen will guess its own values.
*/
movq $__USER32_DS, 4*8(%rsp)
movq $__USER32_CS, 1*8(%rsp)
jmp entry_SYSENTER_compat_after_hwframe
SYM_CODE_END(xen_sysenter_target)
#else /* !CONFIG_IA32_EMULATION */
SYM_CODE_START(xen_syscall32_target)
SYM_CODE_START(xen_sysenter_target)
UNWIND_HINT_EMPTY
ENDBR
lea 16(%rsp), %rsp /* strip %rcx, %r11 */
mov $-ENOSYS, %rax
pushq $0
jmp hypercall_iret
SYM_CODE_END(xen_sysenter_target)
SYM_CODE_END(xen_syscall32_target)
#endif /* CONFIG_IA32_EMULATION */
|
