Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/cpu_switch.S
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1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * William Jolitz. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $FreeBSD: releng/5.1/sys/amd64/amd64/cpu_switch.S 115006 2003-05-15 00:23:40Z peter $ 37 */ 38 39 #include <machine/asmacros.h> 40 41 #include "assym.s" 42 43 /*****************************************************************************/ 44 /* Scheduling */ 45 /*****************************************************************************/ 46 47 .text 48 49 /* 50 * cpu_throw() 51 * 52 * This is the second half of cpu_swtch(). It is used when the current 53 * thread is either a dummy or slated to die, and we no longer care 54 * about its state. This is only a slight optimization and is probably 55 * not worth it anymore. Note that we need to clear the pm_active bits so 56 * we do need the old proc if it still exists. 57 * %rdi = oldtd 58 * %rsi = newtd 59 */ 60 ENTRY(cpu_throw) 61 xorq %rax, %rax 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 btrq %rax, VM_PMAP+PM_ACTIVE(%rdx) /* clear old */ 69 1: 70 movq TD_PCB(%rsi),%rdx /* newtd->td_proc */ 71 movq PCB_CR3(%rdx),%rdx 72 movq %rdx,%cr3 /* new address space */ 73 /* set bit in new pm_active */ 74 movq TD_PROC(%rsi),%rdx 75 movq P_VMSPACE(%rdx), %rdx 76 btsq %rax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */ 77 jmp sw1 78 79 /* 80 * cpu_switch(old, new) 81 * 82 * Save the current thread state, then select the next thread to run 83 * and load its state. 84 * %rdi = oldtd 85 * %rsi = newtd 86 */ 87 ENTRY(cpu_switch) 88 89 /* Switch to new thread. First, save context. */ 90 #ifdef INVARIANTS 91 testq %rdi,%rdi /* no thread? */ 92 jz badsw2 /* no, panic */ 93 #endif 94 95 movq TD_PCB(%rdi),%r8 96 97 movq (%rsp),%rax /* Hardware registers */ 98 movq %rax,PCB_RIP(%r8) 99 movq %rbx,PCB_RBX(%r8) 100 movq %rsp,PCB_RSP(%r8) 101 movq %rbp,PCB_RBP(%r8) 102 movq %r12,PCB_R12(%r8) 103 movq %r13,PCB_R13(%r8) 104 movq %r14,PCB_R14(%r8) 105 movq %r15,PCB_R15(%r8) 106 pushfq /* PSL */ 107 popq PCB_RFLAGS(%r8) 108 109 /* Save userland %fs */ 110 movl $MSR_FSBASE,%ecx 111 rdmsr 112 movl %eax,PCB_FSBASE(%r8) 113 movl %edx,PCB_FSBASE+4(%r8) 114 115 /* Save userland %gs */ 116 movl $MSR_KGSBASE,%ecx 117 rdmsr 118 movl %eax,PCB_GSBASE(%r8) 119 movl %edx,PCB_GSBASE+4(%r8) 120 121 /* Save segment selector numbers */ 122 movl %ds,PCB_DS(%r8) 123 movl %es,PCB_ES(%r8) 124 movl %fs,PCB_FS(%r8) 125 movl %gs,PCB_GS(%r8) 126 127 /* have we used fp, and need a save? */ 128 cmpq %rdi,PCPU(FPCURTHREAD) 129 jne 1f 130 pushq %rdi 131 pushq %rsi 132 addq $PCB_SAVEFPU,%r8 /* h/w bugs make saving complicated */ 133 movq %r8, %rdi 134 call npxsave /* do it in a big C function */ 135 popq %rsi 136 popq %rdi 137 1: 138 139 /* Save is done. Now fire up new thread. Leave old vmspace. */ 140 #ifdef INVARIANTS 141 testq %rsi,%rsi /* no thread? */ 142 jz badsw3 /* no, panic */ 143 #endif 144 movq TD_PCB(%rsi),%r8 145 xorq %rax, %rax 146 movl PCPU(CPUID), %eax 147 148 /* switch address space */ 149 movq PCB_CR3(%r8),%rdx 150 movq %rdx,%cr3 /* new address space */ 151 152 /* Release bit from old pmap->pm_active */ 153 movq TD_PROC(%rdi), %rdx /* oldproc */ 154 movq P_VMSPACE(%rdx), %rdx 155 btrq %rax, VM_PMAP+PM_ACTIVE(%rdx) /* clear old */ 156 157 /* Set bit in new pmap->pm_active */ 158 movq TD_PROC(%rsi),%rdx /* newproc */ 159 movq P_VMSPACE(%rdx), %rdx 160 btsq %rax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */ 161 162 sw1: 163 /* 164 * At this point, we've switched address spaces and are ready 165 * to load up the rest of the next context. 166 */ 167 movq TD_PCB(%rsi),%r8 168 169 /* Restore segment selector numbers */ 170 movl PCB_DS(%r8),%ds 171 movl PCB_ES(%r8),%es 172 movl PCB_FS(%r8),%fs 173 174 /* Restore userland %gs while preserving kernel gsbase */ 175 movl $MSR_GSBASE,%ecx 176 rdmsr 177 movl PCB_GS(%r8),%gs 178 wrmsr 179 180 /* Restore userland %fs */ 181 movl $MSR_FSBASE,%ecx 182 movl PCB_FSBASE(%r8),%eax 183 movl PCB_FSBASE+4(%r8),%edx 184 wrmsr 185 186 /* Restore userland %gs */ 187 movl $MSR_KGSBASE,%ecx 188 movl PCB_GSBASE(%r8),%eax 189 movl PCB_GSBASE+4(%r8),%edx 190 wrmsr 191 192 /* Update the TSS_RSP0 pointer for the next interrupt */ 193 leaq -16(%r8), %rbx 194 movq %rbx, common_tss + COMMON_TSS_RSP0 195 196 /* Restore context. */ 197 movq PCB_RBX(%r8),%rbx 198 movq PCB_RSP(%r8),%rsp 199 movq PCB_RBP(%r8),%rbp 200 movq PCB_R12(%r8),%r12 201 movq PCB_R13(%r8),%r13 202 movq PCB_R14(%r8),%r14 203 movq PCB_R15(%r8),%r15 204 movq PCB_RIP(%r8),%rax 205 movq %rax,(%rsp) 206 pushq PCB_RFLAGS(%r8) 207 popfq 208 209 movq %r8, PCPU(CURPCB) 210 movq %rsi, PCPU(CURTHREAD) /* into next thread */ 211 212 ret 213 214 #ifdef INVARIANTS 215 badsw1: 216 pushq %rax 217 pushq %rcx 218 pushq %rdx 219 pushq %rbx 220 pushq %rbp 221 pushq %rsi 222 pushq %rdi 223 pushq %r8 224 pushq %r9 225 pushq %r10 226 pushq %r11 227 pushq %r12 228 pushq %r13 229 pushq %r14 230 pushq %r15 231 pushq $sw0_1 232 call panic 233 sw0_1: .asciz "cpu_throw: no newthread supplied" 234 235 badsw2: 236 pushq %rax 237 pushq %rcx 238 pushq %rdx 239 pushq %rbx 240 pushq %rbp 241 pushq %rsi 242 pushq %rdi 243 pushq %r8 244 pushq %r9 245 pushq %r10 246 pushq %r11 247 pushq %r12 248 pushq %r13 249 pushq %r14 250 pushq %r15 251 pushq $sw0_2 252 call panic 253 sw0_2: .asciz "cpu_switch: no curthread supplied" 254 255 badsw3: 256 pushq %rax 257 pushq %rcx 258 pushq %rdx 259 pushq %rbx 260 pushq %rbp 261 pushq %rsi 262 pushq %rdi 263 pushq %r8 264 pushq %r9 265 pushq %r10 266 pushq %r11 267 pushq %r12 268 pushq %r13 269 pushq %r14 270 pushq %r15 271 pushq $sw0_3 272 call panic 273 sw0_3: .asciz "cpu_switch: no newthread supplied" 274 #endif 275 276 noswitch: .asciz "cpu_switch: called!" 277 nothrow: .asciz "cpu_throw: called!" 278 /* 279 * savectx(pcb) 280 * Update pcb, saving current processor state. 281 */ 282 ENTRY(savectx) 283 /* Fetch PCB. */ 284 movq %rdi,%rcx 285 286 /* Save caller's return address. */ 287 movq (%rsp),%rax 288 movq %rax,PCB_RIP(%rcx) 289 290 movq %cr3,%rax 291 movq %rax,PCB_CR3(%rcx) 292 293 movq %rbx,PCB_RBX(%rcx) 294 movq %rsp,PCB_RSP(%rcx) 295 movq %rbp,PCB_RBP(%rcx) 296 movq %r12,PCB_R12(%rcx) 297 movq %r13,PCB_R13(%rcx) 298 movq %r14,PCB_R14(%rcx) 299 movq %r15,PCB_R15(%rcx) 300 pushfq 301 popq PCB_RFLAGS(%rcx) 302 303 /* 304 * If fpcurthread == NULL, then the npx h/w state is irrelevant and the 305 * state had better already be in the pcb. This is true for forks 306 * but not for dumps (the old book-keeping with FP flags in the pcb 307 * always lost for dumps because the dump pcb has 0 flags). 308 * 309 * If fpcurthread != NULL, then we have to save the npx h/w state to 310 * fpcurthread's pcb and copy it to the requested pcb, or save to the 311 * requested pcb and reload. Copying is easier because we would 312 * have to handle h/w bugs for reloading. We used to lose the 313 * parent's npx state for forks by forgetting to reload. 314 */ 315 pushfq 316 cli 317 movq PCPU(FPCURTHREAD),%rax 318 testq %rax,%rax 319 je 1f 320 321 pushq %rcx 322 pushq %rax 323 movq TD_PCB(%rax),%rdi 324 leaq PCB_SAVEFPU(%rdi),%rdi 325 call npxsave 326 popq %rax 327 popq %rcx 328 329 movq $PCB_SAVEFPU_SIZE,%rdx /* arg 3 */ 330 leaq PCB_SAVEFPU(%rcx),%rsi /* arg 2 */ 331 movq %rax,%rdi /* arg 1 */ 332 call bcopy 333 1: 334 popfq 335 336 ret
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