cpu_switch.S revision 151429 
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: head/sys/amd64/amd64/cpu_switch.S 151429 2005-10-17 23:10:31Z davidxu $
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 */
64ENTRY(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 */
721:
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 */
90ENTRY(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)
1121:
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)
1301:
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	xorl	%eax,%eax
142	movq	%rax,PCPU(FPCURTHREAD)
1431:
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
166sw1:
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
1871:
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
2002:
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
2431:
244	ret
245
246/*
247 * savectx(pcb)
248 * Update pcb, saving current processor state.
249 */
250ENTRY(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
2991:
300	popfq
301
302	ret
303