2 * Copyright (c) 2003 Peter Wemm.
3 * Copyright (c) 1990 The Regents of the University of California.
6 * This code is derived from software contributed to Berkeley by
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10 * modification, are permitted provided that the following conditions
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.
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
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36 #include <machine/asmacros.h>
37 #include <machine/specialreg.h>
41 /*****************************************************************************/
43 /*****************************************************************************/
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.
65 movl PCPU(CPUID), %eax
66 testq %rdi,%rdi /* no thread? */
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 */
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 */
83 * cpu_switch(old, new)
85 * Save the current thread state, then select the next thread to run
91 /* Switch to new thread. First, save context. */
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)
104 testl $PCB_32BIT,PCB_FLAGS(%r8)
105 jz 1f /* no, skip over */
107 /* Save segment selector numbers */
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 */
121 movq %rax,PCB_DR6(%r8)
123 movq %rax,PCB_DR3(%r8)
125 movq %rax,PCB_DR2(%r8)
127 movq %rax,PCB_DR1(%r8)
129 movq %rax,PCB_DR0(%r8)
132 /* have we used fp, and need a save? */
133 cmpq %rdi,PCPU(FPCURTHREAD)
135 addq $PCB_SAVEFPU,%r8
142 movq %rax,PCPU(FPCURTHREAD)
145 /* Save is done. Now fire up new thread. Leave old vmspace. */
146 movq TD_PCB(%rsi),%r8
148 /* switch address space */
149 movq PCB_CR3(%r8),%rdx
151 cmpq %rdx,%rax /* Same address space? */
153 movq %rdx,%cr3 /* new address space */
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 */
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 */
168 * At this point, we've switched address spaces and are ready
169 * to load up the rest of the next context.
171 movq TD_PCB(%rsi),%r8
173 testl $PCB_32BIT,PCB_FLAGS(%r8)
174 jz 1f /* no, skip over */
176 /* Restore segment selector numbers */
181 /* Restore userland %gs while preserving kernel gsbase */
182 movl $MSR_GSBASE,%ecx
189 /* Restore userland %fs */
190 movl $MSR_FSBASE,%ecx
191 movl PCB_FSBASE(%r8),%eax
192 movl PCB_FSBASE+4(%r8),%edx
195 /* Restore userland %gs */
196 movl $MSR_KGSBASE,%ecx
197 movl PCB_GSBASE(%r8),%eax
198 movl PCB_GSBASE+4(%r8),%edx
202 /* Update the TSS_RSP0 pointer for the next interrupt */
203 movq PCPU(TSSP), %rax
204 addq $COMMON_TSS_RSP0, %rax
207 movq %rbx, PCPU(RSP0)
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
220 movq %r8, PCPU(CURPCB)
221 movq %rsi, PCPU(CURTHREAD) /* into next thread */
223 /* Test if debug registers should be restored. */
224 testl $PCB_DBREGS,PCB_FLAGS(%r8)
226 movq PCB_DR6(%r8),%rax
228 movq PCB_DR3(%r8),%rax
230 movq PCB_DR2(%r8),%rax
232 movq PCB_DR1(%r8),%rax
234 movq PCB_DR0(%r8),%rax
236 /* But preserve reserved bits in %dr7 */
238 andq $0x0000fc00,%rax
239 movq PCB_DR7(%r8),%rcx
240 andq $~0x0000fc00,%rcx
248 * Update pcb, saving current processor state.
254 /* Save caller's return address. */
256 movq %rax,PCB_RIP(%rcx)
259 movq %rax,PCB_CR3(%rcx)
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)
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).
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.
283 movq PCPU(FPCURTHREAD),%rax
287 movq TD_PCB(%rax),%rdi
288 leaq PCB_SAVEFPU(%rdi),%rdi
295 movq $PCB_SAVEFPU_SIZE,%rdx /* arg 3 */
296 leaq PCB_SAVEFPU(%rcx),%rsi /* arg 2 */
297 /* arg 1 (%rdi) already loaded */