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 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * $FreeBSD: releng/5.2/sys/amd64/amd64/cpu_switch.S 122849 2003-11-17 08:58:16Z peter $
38 */
39
40 #include <machine/asmacros.h>
41
42 #include "assym.s"
43
44 /*****************************************************************************/
45 /* Scheduling */
46 /*****************************************************************************/
47
48 .text
49
50 /*
51 * cpu_throw()
52 *
53 * This is the second half of cpu_swtch(). It is used when the current
54 * thread is either a dummy or slated to die, and we no longer care
55 * about its state. This is only a slight optimization and is probably
56 * not worth it anymore. Note that we need to clear the pm_active bits so
57 * we do need the old proc if it still exists.
58 * %rdi = oldtd
59 * %rsi = newtd
60 */
61 ENTRY(cpu_throw)
62 movl PCPU(CPUID), %eax
63 testq %rdi,%rdi /* no thread? */
64 jz 1f
65 /* release bit from old pm_active */
66 movq TD_PROC(%rdi), %rdx /* oldtd->td_proc */
67 movq P_VMSPACE(%rdx), %rdx /* proc->p_vmspace */
68 #ifdef SMP
69 lock
70 #endif
71 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 #ifdef SMP
80 lock
81 #endif
82 btsl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */
83 jmp sw1
84
85 /*
86 * cpu_switch(old, new)
87 *
88 * Save the current thread state, then select the next thread to run
89 * and load its state.
90 * %rdi = oldtd
91 * %rsi = newtd
92 */
93 ENTRY(cpu_switch)
94
95 /* Switch to new thread. First, save context. */
96 #ifdef INVARIANTS
97 testq %rdi,%rdi /* no thread? */
98 jz badsw2 /* no, panic */
99 #endif
100
101 movq TD_PCB(%rdi),%r8
102
103 movq (%rsp),%rax /* Hardware registers */
104 movq %rax,PCB_RIP(%r8)
105 movq %rbx,PCB_RBX(%r8)
106 movq %rsp,PCB_RSP(%r8)
107 movq %rbp,PCB_RBP(%r8)
108 movq %r12,PCB_R12(%r8)
109 movq %r13,PCB_R13(%r8)
110 movq %r14,PCB_R14(%r8)
111 movq %r15,PCB_R15(%r8)
112 pushfq /* PSL */
113 popq PCB_RFLAGS(%r8)
114
115 /* Save userland %fs */
116 movl $MSR_FSBASE,%ecx
117 rdmsr
118 movl %eax,PCB_FSBASE(%r8)
119 movl %edx,PCB_FSBASE+4(%r8)
120
121 /* Save userland %gs */
122 movl $MSR_KGSBASE,%ecx
123 rdmsr
124 movl %eax,PCB_GSBASE(%r8)
125 movl %edx,PCB_GSBASE+4(%r8)
126
127 /* Save segment selector numbers */
128 movl %ds,PCB_DS(%r8)
129 movl %es,PCB_ES(%r8)
130 movl %fs,PCB_FS(%r8)
131 movl %gs,PCB_GS(%r8)
132
133 /* have we used fp, and need a save? */
134 cmpq %rdi,PCPU(FPCURTHREAD)
135 jne 1f
136 pushq %rdi
137 pushq %rsi
138 addq $PCB_SAVEFPU,%r8 /* h/w bugs make saving complicated */
139 movq %r8, %rdi
140 call fpusave /* do it in a big C function */
141 popq %rsi
142 popq %rdi
143 1:
144
145 /* Save is done. Now fire up new thread. Leave old vmspace. */
146 #ifdef INVARIANTS
147 testq %rsi,%rsi /* no thread? */
148 jz badsw3 /* no, panic */
149 #endif
150 movq TD_PCB(%rsi),%r8
151 movl PCPU(CPUID), %eax
152
153 /* switch address space */
154 movq PCB_CR3(%r8),%rdx
155 movq %rdx,%cr3 /* new address space */
156
157 /* Release bit from old pmap->pm_active */
158 movq TD_PROC(%rdi), %rdx /* oldproc */
159 movq P_VMSPACE(%rdx), %rdx
160 #ifdef SMP
161 lock
162 #endif
163 btrl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* clear old */
164
165 /* Set bit in new pmap->pm_active */
166 movq TD_PROC(%rsi),%rdx /* newproc */
167 movq P_VMSPACE(%rdx), %rdx
168 #ifdef SMP
169 lock
170 #endif
171 btsl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */
172
173 sw1:
174 /*
175 * At this point, we've switched address spaces and are ready
176 * to load up the rest of the next context.
177 */
178 movq TD_PCB(%rsi),%r8
179
180 /* Restore segment selector numbers */
181 movl PCB_DS(%r8),%ds
182 movl PCB_ES(%r8),%es
183 movl PCB_FS(%r8),%fs
184
185 /* Restore userland %gs while preserving kernel gsbase */
186 movl $MSR_GSBASE,%ecx
187 rdmsr
188 movl PCB_GS(%r8),%gs
189 wrmsr
190
191 /* Restore userland %fs */
192 movl $MSR_FSBASE,%ecx
193 movl PCB_FSBASE(%r8),%eax
194 movl PCB_FSBASE+4(%r8),%edx
195 wrmsr
196
197 /* Restore userland %gs */
198 movl $MSR_KGSBASE,%ecx
199 movl PCB_GSBASE(%r8),%eax
200 movl PCB_GSBASE+4(%r8),%edx
201 wrmsr
202
203 /* Update the TSS_RSP0 pointer for the next interrupt */
204 movq PCPU(TSSP), %rax
205 addq $COMMON_TSS_RSP0, %rax
206 leaq -16(%r8), %rbx
207 movq %rbx, (%rax)
208 movq %rbx, PCPU(RSP0)
209
210 /* Restore context. */
211 movq PCB_RBX(%r8),%rbx
212 movq PCB_RSP(%r8),%rsp
213 movq PCB_RBP(%r8),%rbp
214 movq PCB_R12(%r8),%r12
215 movq PCB_R13(%r8),%r13
216 movq PCB_R14(%r8),%r14
217 movq PCB_R15(%r8),%r15
218 movq PCB_RIP(%r8),%rax
219 movq %rax,(%rsp)
220 pushq PCB_RFLAGS(%r8)
221 popfq
222
223 movq %r8, PCPU(CURPCB)
224 movq %rsi, PCPU(CURTHREAD) /* into next thread */
225
226 ret
227
228 #ifdef INVARIANTS
229 badsw1:
230 pushq %rax
231 pushq %rcx
232 pushq %rdx
233 pushq %rbx
234 pushq %rbp
235 pushq %rsi
236 pushq %rdi
237 pushq %r8
238 pushq %r9
239 pushq %r10
240 pushq %r11
241 pushq %r12
242 pushq %r13
243 pushq %r14
244 pushq %r15
245 pushq $sw0_1
246 call panic
247 sw0_1: .asciz "cpu_throw: no newthread supplied"
248
249 badsw2:
250 pushq %rax
251 pushq %rcx
252 pushq %rdx
253 pushq %rbx
254 pushq %rbp
255 pushq %rsi
256 pushq %rdi
257 pushq %r8
258 pushq %r9
259 pushq %r10
260 pushq %r11
261 pushq %r12
262 pushq %r13
263 pushq %r14
264 pushq %r15
265 pushq $sw0_2
266 call panic
267 sw0_2: .asciz "cpu_switch: no curthread supplied"
268
269 badsw3:
270 pushq %rax
271 pushq %rcx
272 pushq %rdx
273 pushq %rbx
274 pushq %rbp
275 pushq %rsi
276 pushq %rdi
277 pushq %r8
278 pushq %r9
279 pushq %r10
280 pushq %r11
281 pushq %r12
282 pushq %r13
283 pushq %r14
284 pushq %r15
285 pushq $sw0_3
286 call panic
287 sw0_3: .asciz "cpu_switch: no newthread supplied"
288 #endif
289
290 noswitch: .asciz "cpu_switch: called!"
291 nothrow: .asciz "cpu_throw: called!"
292 /*
293 * savectx(pcb)
294 * Update pcb, saving current processor state.
295 */
296 ENTRY(savectx)
297 /* Fetch PCB. */
298 movq %rdi,%rcx
299
300 /* Save caller's return address. */
301 movq (%rsp),%rax
302 movq %rax,PCB_RIP(%rcx)
303
304 movq %cr3,%rax
305 movq %rax,PCB_CR3(%rcx)
306
307 movq %rbx,PCB_RBX(%rcx)
308 movq %rsp,PCB_RSP(%rcx)
309 movq %rbp,PCB_RBP(%rcx)
310 movq %r12,PCB_R12(%rcx)
311 movq %r13,PCB_R13(%rcx)
312 movq %r14,PCB_R14(%rcx)
313 movq %r15,PCB_R15(%rcx)
314 pushfq
315 popq PCB_RFLAGS(%rcx)
316
317 /*
318 * If fpcurthread == NULL, then the fpu h/w state is irrelevant and the
319 * state had better already be in the pcb. This is true for forks
320 * but not for dumps (the old book-keeping with FP flags in the pcb
321 * always lost for dumps because the dump pcb has 0 flags).
322 *
323 * If fpcurthread != NULL, then we have to save the fpu h/w state to
324 * fpcurthread's pcb and copy it to the requested pcb, or save to the
325 * requested pcb and reload. Copying is easier because we would
326 * have to handle h/w bugs for reloading. We used to lose the
327 * parent's fpu state for forks by forgetting to reload.
328 */
329 pushfq
330 cli
331 movq PCPU(FPCURTHREAD),%rax
332 testq %rax,%rax
333 je 1f
334
335 pushq %rcx
336 pushq %rax
337 movq TD_PCB(%rax),%rdi
338 leaq PCB_SAVEFPU(%rdi),%rdi
339 call fpusave
340 popq %rax
341 popq %rcx
342
343 movq $PCB_SAVEFPU_SIZE,%rdx /* arg 3 */
344 leaq PCB_SAVEFPU(%rcx),%rsi /* arg 2 */
345 movq %rax,%rdi /* arg 1 */
346 call bcopy
347 1:
348 popfq
349
350 ret
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