1 /*-
2 * Copyright (c) 2003 Peter Wemm.
3 * Copyright (c) 1990 The Regents of the University of California.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * William Jolitz.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: releng/6.2/sys/amd64/amd64/cpu_switch.S 152442 2005-11-15 00:26:00Z peter $
34 */
35
36 #include <machine/asmacros.h>
37 #include <machine/specialreg.h>
38
39 #include "assym.s"
40
41 /*****************************************************************************/
42 /* Scheduling */
43 /*****************************************************************************/
44
45 .text
46
47 #ifdef SMP
48 #define LK lock ;
49 #else
50 #define LK
51 #endif
52
53 /*
54 * cpu_throw()
55 *
56 * This is the second half of cpu_switch(). It is used when the current
57 * thread is either a dummy or slated to die, and we no longer care
58 * about its state. This is only a slight optimization and is probably
59 * not worth it anymore. Note that we need to clear the pm_active bits so
60 * we do need the old proc if it still exists.
61 * %rdi = oldtd
62 * %rsi = newtd
63 */
64 ENTRY(cpu_throw)
65 movl PCPU(CPUID), %eax
66 testq %rdi,%rdi /* no thread? */
67 jz 1f
68 /* release bit from old pm_active */
69 movq TD_PROC(%rdi), %rdx /* oldtd->td_proc */
70 movq P_VMSPACE(%rdx), %rdx /* proc->p_vmspace */
71 LK btrl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* clear old */
72 1:
73 movq TD_PCB(%rsi),%rdx /* newtd->td_proc */
74 movq PCB_CR3(%rdx),%rdx
75 movq %rdx,%cr3 /* new address space */
76 /* set bit in new pm_active */
77 movq TD_PROC(%rsi),%rdx
78 movq P_VMSPACE(%rdx), %rdx
79 LK btsl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */
80 jmp sw1
81
82 /*
83 * cpu_switch(old, new)
84 *
85 * Save the current thread state, then select the next thread to run
86 * and load its state.
87 * %rdi = oldtd
88 * %rsi = newtd
89 */
90 ENTRY(cpu_switch)
91 /* Switch to new thread. First, save context. */
92 movq TD_PCB(%rdi),%r8
93
94 movq (%rsp),%rax /* Hardware registers */
95 movq %rax,PCB_RIP(%r8)
96 movq %rbx,PCB_RBX(%r8)
97 movq %rsp,PCB_RSP(%r8)
98 movq %rbp,PCB_RBP(%r8)
99 movq %r12,PCB_R12(%r8)
100 movq %r13,PCB_R13(%r8)
101 movq %r14,PCB_R14(%r8)
102 movq %r15,PCB_R15(%r8)
103
104 testl $PCB_32BIT,PCB_FLAGS(%r8)
105 jz 1f /* no, skip over */
106
107 /* Save segment selector numbers */
108 movl %ds,PCB_DS(%r8)
109 movl %es,PCB_ES(%r8)
110 movl %fs,PCB_FS(%r8)
111 movl %gs,PCB_GS(%r8)
112 1:
113 /* Test if debug registers should be saved. */
114 testl $PCB_DBREGS,PCB_FLAGS(%r8)
115 jz 1f /* no, skip over */
116 movq %dr7,%rax /* yes, do the save */
117 movq %rax,PCB_DR7(%r8)
118 andq $0x0000fc00, %rax /* disable all watchpoints */
119 movq %rax,%dr7
120 movq %dr6,%rax
121 movq %rax,PCB_DR6(%r8)
122 movq %dr3,%rax
123 movq %rax,PCB_DR3(%r8)
124 movq %dr2,%rax
125 movq %rax,PCB_DR2(%r8)
126 movq %dr1,%rax
127 movq %rax,PCB_DR1(%r8)
128 movq %dr0,%rax
129 movq %rax,PCB_DR0(%r8)
130 1:
131
132 /* have we used fp, and need a save? */
133 cmpq %rdi,PCPU(FPCURTHREAD)
134 jne 1f
135 addq $PCB_SAVEFPU,%r8
136 clts
137 fxsave (%r8)
138 smsw %ax
139 orb $CR0_TS,%al
140 lmsw %ax
141 xorq %rax,%rax
142 movq %rax,PCPU(FPCURTHREAD)
143 1:
144
145 /* Save is done. Now fire up new thread. Leave old vmspace. */
146 movq TD_PCB(%rsi),%r8
147
148 /* switch address space */
149 movq PCB_CR3(%r8),%rdx
150 movq %cr3,%rax
151 cmpq %rdx,%rax /* Same address space? */
152 je sw1
153 movq %rdx,%cr3 /* new address space */
154
155 movl PCPU(CPUID), %eax
156 /* Release bit from old pmap->pm_active */
157 movq TD_PROC(%rdi), %rdx /* oldproc */
158 movq P_VMSPACE(%rdx), %rdx
159 LK btrl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* clear old */
160
161 /* Set bit in new pmap->pm_active */
162 movq TD_PROC(%rsi),%rdx /* newproc */
163 movq P_VMSPACE(%rdx), %rdx
164 LK btsl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */
165
166 sw1:
167 /*
168 * At this point, we've switched address spaces and are ready
169 * to load up the rest of the next context.
170 */
171 movq TD_PCB(%rsi),%r8
172
173 testl $PCB_32BIT,PCB_FLAGS(%r8)
174 jz 1f /* no, skip over */
175
176 /* Restore segment selector numbers */
177 movl PCB_DS(%r8),%ds
178 movl PCB_ES(%r8),%es
179 movl PCB_FS(%r8),%fs
180
181 /* Restore userland %gs while preserving kernel gsbase */
182 movl $MSR_GSBASE,%ecx
183 rdmsr
184 movl PCB_GS(%r8),%gs
185 wrmsr
186 jmp 2f
187 1:
188
189 /* Restore userland %fs */
190 movl $MSR_FSBASE,%ecx
191 movl PCB_FSBASE(%r8),%eax
192 movl PCB_FSBASE+4(%r8),%edx
193 wrmsr
194
195 /* Restore userland %gs */
196 movl $MSR_KGSBASE,%ecx
197 movl PCB_GSBASE(%r8),%eax
198 movl PCB_GSBASE+4(%r8),%edx
199 wrmsr
200 2:
201
202 /* Update the TSS_RSP0 pointer for the next interrupt */
203 movq PCPU(TSSP), %rax
204 addq $COMMON_TSS_RSP0, %rax
205 leaq -16(%r8), %rbx
206 movq %rbx, (%rax)
207 movq %rbx, PCPU(RSP0)
208
209 /* Restore context. */
210 movq PCB_RBX(%r8),%rbx
211 movq PCB_RSP(%r8),%rsp
212 movq PCB_RBP(%r8),%rbp
213 movq PCB_R12(%r8),%r12
214 movq PCB_R13(%r8),%r13
215 movq PCB_R14(%r8),%r14
216 movq PCB_R15(%r8),%r15
217 movq PCB_RIP(%r8),%rax
218 movq %rax,(%rsp)
219
220 movq %r8, PCPU(CURPCB)
221 movq %rsi, PCPU(CURTHREAD) /* into next thread */
222
223 /* Test if debug registers should be restored. */
224 testl $PCB_DBREGS,PCB_FLAGS(%r8)
225 jz 1f
226 movq PCB_DR6(%r8),%rax
227 movq %rax,%dr6
228 movq PCB_DR3(%r8),%rax
229 movq %rax,%dr3
230 movq PCB_DR2(%r8),%rax
231 movq %rax,%dr2
232 movq PCB_DR1(%r8),%rax
233 movq %rax,%dr1
234 movq PCB_DR0(%r8),%rax
235 movq %rax,%dr0
236 /* But preserve reserved bits in %dr7 */
237 movq %dr7,%rax
238 andq $0x0000fc00,%rax
239 movq PCB_DR7(%r8),%rcx
240 andq $~0x0000fc00,%rcx
241 orq %rcx,%rax
242 movq %rax,%dr7
243 1:
244 ret
245
246 /*
247 * savectx(pcb)
248 * Update pcb, saving current processor state.
249 */
250 ENTRY(savectx)
251 /* Fetch PCB. */
252 movq %rdi,%rcx
253
254 /* Save caller's return address. */
255 movq (%rsp),%rax
256 movq %rax,PCB_RIP(%rcx)
257
258 movq %cr3,%rax
259 movq %rax,PCB_CR3(%rcx)
260
261 movq %rbx,PCB_RBX(%rcx)
262 movq %rsp,PCB_RSP(%rcx)
263 movq %rbp,PCB_RBP(%rcx)
264 movq %r12,PCB_R12(%rcx)
265 movq %r13,PCB_R13(%rcx)
266 movq %r14,PCB_R14(%rcx)
267 movq %r15,PCB_R15(%rcx)
268
269 /*
270 * If fpcurthread == NULL, then the fpu h/w state is irrelevant and the
271 * state had better already be in the pcb. This is true for forks
272 * but not for dumps (the old book-keeping with FP flags in the pcb
273 * always lost for dumps because the dump pcb has 0 flags).
274 *
275 * If fpcurthread != NULL, then we have to save the fpu h/w state to
276 * fpcurthread's pcb and copy it to the requested pcb, or save to the
277 * requested pcb and reload. Copying is easier because we would
278 * have to handle h/w bugs for reloading. We used to lose the
279 * parent's fpu state for forks by forgetting to reload.
280 */
281 pushfq
282 cli
283 movq PCPU(FPCURTHREAD),%rax
284 testq %rax,%rax
285 je 1f
286
287 movq TD_PCB(%rax),%rdi
288 leaq PCB_SAVEFPU(%rdi),%rdi
289 clts
290 fxsave (%rdi)
291 smsw %ax
292 orb $CR0_TS,%al
293 lmsw %ax
294
295 movq $PCB_SAVEFPU_SIZE,%rdx /* arg 3 */
296 leaq PCB_SAVEFPU(%rcx),%rsi /* arg 2 */
297 /* arg 1 (%rdi) already loaded */
298 call bcopy
299 1:
300 popfq
301
302 ret
Cache object: 6ec0c879b187a59251948c4b67d34b60
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