Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/amd64/amd64/cpu_switch.S
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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/11.1/sys/amd64/amd64/cpu_switch.S 335465 2018-06-21 05:17:13Z gordon $ 34 */ 35 36 #include <machine/asmacros.h> 37 #include <machine/specialreg.h> 38 39 #include "assym.s" 40 #include "opt_sched.h" 41 42 /*****************************************************************************/ 43 /* Scheduling */ 44 /*****************************************************************************/ 45 46 .text 47 48 #ifdef SMP 49 #define LK lock ; 50 #else 51 #define LK 52 #endif 53 54 #if defined(SCHED_ULE) && defined(SMP) 55 #define SETLK xchgq 56 #else 57 #define SETLK movq 58 #endif 59 60 /* 61 * cpu_throw() 62 * 63 * This is the second half of cpu_switch(). It is used when the current 64 * thread is either a dummy or slated to die, and we no longer care 65 * about its state. This is only a slight optimization and is probably 66 * not worth it anymore. Note that we need to clear the pm_active bits so 67 * we do need the old proc if it still exists. 68 * %rdi = oldtd 69 * %rsi = newtd 70 */ 71 ENTRY(cpu_throw) 72 movq %rsi,%r12 73 movq %rsi,%rdi 74 call pmap_activate_sw 75 jmp sw1 76 END(cpu_throw) 77 78 /* 79 * cpu_switch(old, new, mtx) 80 * 81 * Save the current thread state, then select the next thread to run 82 * and load its state. 83 * %rdi = oldtd 84 * %rsi = newtd 85 * %rdx = mtx 86 */ 87 ENTRY(cpu_switch) 88 /* Switch to new thread. First, save context. */ 89 movq TD_PCB(%rdi),%r8 90 orl $PCB_FULL_IRET,PCB_FLAGS(%r8) 91 92 movq (%rsp),%rax /* Hardware registers */ 93 movq %r15,PCB_R15(%r8) 94 movq %r14,PCB_R14(%r8) 95 movq %r13,PCB_R13(%r8) 96 movq %r12,PCB_R12(%r8) 97 movq %rbp,PCB_RBP(%r8) 98 movq %rsp,PCB_RSP(%r8) 99 movq %rbx,PCB_RBX(%r8) 100 movq %rax,PCB_RIP(%r8) 101 102 testl $PCB_DBREGS,PCB_FLAGS(%r8) 103 jnz store_dr /* static predict not taken */ 104 done_store_dr: 105 106 /* have we used fp, and need a save? */ 107 cmpq %rdi,PCPU(FPCURTHREAD) 108 jne 2f 109 movq PCB_SAVEFPU(%r8),%r8 110 clts 111 cmpl $0,use_xsave(%rip) 112 jne 1f 113 fxsave (%r8) 114 jmp 2f 115 1: movq %rdx,%rcx 116 movl xsave_mask,%eax 117 movl xsave_mask+4,%edx 118 .globl ctx_switch_xsave 119 ctx_switch_xsave: 120 /* This is patched to xsaveopt if supported, see fpuinit_bsp1() */ 121 xsave (%r8) 122 movq %rcx,%rdx 123 2: 124 /* Save is done. Now fire up new thread. Leave old vmspace. */ 125 movq %rsi,%r12 126 movq %rdi,%r13 127 movq %rdx,%r15 128 movq %rsi,%rdi 129 callq pmap_activate_sw 130 SETLK %r15,TD_LOCK(%r13) /* Release the old thread */ 131 sw1: 132 movq TD_PCB(%r12),%r8 133 #if defined(SCHED_ULE) && defined(SMP) 134 /* Wait for the new thread to become unblocked */ 135 movq $blocked_lock, %rdx 136 1: 137 movq TD_LOCK(%r12),%rcx 138 cmpq %rcx, %rdx 139 pause 140 je 1b 141 #endif 142 /* 143 * At this point, we've switched address spaces and are ready 144 * to load up the rest of the next context. 145 */ 146 147 /* Skip loading user fsbase/gsbase for kthreads */ 148 testl $TDP_KTHREAD,TD_PFLAGS(%r12) 149 jnz do_kthread 150 151 /* 152 * Load ldt register 153 */ 154 movq TD_PROC(%r12),%rcx 155 cmpq $0, P_MD+MD_LDT(%rcx) 156 jne do_ldt 157 xorl %eax,%eax 158 ld_ldt: lldt %ax 159 160 /* Restore fs base in GDT */ 161 movl PCB_FSBASE(%r8),%eax 162 movq PCPU(FS32P),%rdx 163 movw %ax,2(%rdx) 164 shrl $16,%eax 165 movb %al,4(%rdx) 166 shrl $8,%eax 167 movb %al,7(%rdx) 168 169 /* Restore gs base in GDT */ 170 movl PCB_GSBASE(%r8),%eax 171 movq PCPU(GS32P),%rdx 172 movw %ax,2(%rdx) 173 shrl $16,%eax 174 movb %al,4(%rdx) 175 shrl $8,%eax 176 movb %al,7(%rdx) 177 178 do_kthread: 179 /* Do we need to reload tss ? */ 180 movq PCPU(TSSP),%rax 181 movq PCB_TSSP(%r8),%rdx 182 testq %rdx,%rdx 183 cmovzq PCPU(COMMONTSSP),%rdx 184 cmpq %rax,%rdx 185 jne do_tss 186 done_tss: 187 movq %r8,PCPU(RSP0) 188 movq %r8,PCPU(CURPCB) 189 /* Update the COMMON_TSS_RSP0 pointer for the next interrupt */ 190 cmpb $0,pti(%rip) 191 jne 1f 192 movq %r8,COMMON_TSS_RSP0(%rdx) 193 1: movq %r12,PCPU(CURTHREAD) /* into next thread */ 194 195 /* Test if debug registers should be restored. */ 196 testl $PCB_DBREGS,PCB_FLAGS(%r8) 197 jnz load_dr /* static predict not taken */ 198 done_load_dr: 199 200 /* Restore context. */ 201 movq PCB_R15(%r8),%r15 202 movq PCB_R14(%r8),%r14 203 movq PCB_R13(%r8),%r13 204 movq PCB_R12(%r8),%r12 205 movq PCB_RBP(%r8),%rbp 206 movq PCB_RSP(%r8),%rsp 207 movq PCB_RBX(%r8),%rbx 208 movq PCB_RIP(%r8),%rax 209 movq %rax,(%rsp) 210 movq PCPU(CURTHREAD),%rdi 211 call fpu_activate_sw 212 ret 213 214 /* 215 * We order these strangely for several reasons. 216 * 1: I wanted to use static branch prediction hints 217 * 2: Most athlon64/opteron cpus don't have them. They define 218 * a forward branch as 'predict not taken'. Intel cores have 219 * the 'rep' prefix to invert this. 220 * So, to make it work on both forms of cpu we do the detour. 221 * We use jumps rather than call in order to avoid the stack. 222 */ 223 224 store_dr: 225 movq %dr7,%rax /* yes, do the save */ 226 movq %dr0,%r15 227 movq %dr1,%r14 228 movq %dr2,%r13 229 movq %dr3,%r12 230 movq %dr6,%r11 231 movq %r15,PCB_DR0(%r8) 232 movq %r14,PCB_DR1(%r8) 233 movq %r13,PCB_DR2(%r8) 234 movq %r12,PCB_DR3(%r8) 235 movq %r11,PCB_DR6(%r8) 236 movq %rax,PCB_DR7(%r8) 237 andq $0x0000fc00, %rax /* disable all watchpoints */ 238 movq %rax,%dr7 239 jmp done_store_dr 240 241 load_dr: 242 movq %dr7,%rax 243 movq PCB_DR0(%r8),%r15 244 movq PCB_DR1(%r8),%r14 245 movq PCB_DR2(%r8),%r13 246 movq PCB_DR3(%r8),%r12 247 movq PCB_DR6(%r8),%r11 248 movq PCB_DR7(%r8),%rcx 249 movq %r15,%dr0 250 movq %r14,%dr1 251 /* Preserve reserved bits in %dr7 */ 252 andq $0x0000fc00,%rax 253 andq $~0x0000fc00,%rcx 254 movq %r13,%dr2 255 movq %r12,%dr3 256 orq %rcx,%rax 257 movq %r11,%dr6 258 movq %rax,%dr7 259 jmp done_load_dr 260 261 do_tss: movq %rdx,PCPU(TSSP) 262 movq %rdx,%rcx 263 movq PCPU(TSS),%rax 264 movw %cx,2(%rax) 265 shrq $16,%rcx 266 movb %cl,4(%rax) 267 shrq $8,%rcx 268 movb %cl,7(%rax) 269 shrq $8,%rcx 270 movl %ecx,8(%rax) 271 movb $0x89,5(%rax) /* unset busy */ 272 cmpb $0,pti(%rip) 273 je 1f 274 movq PCPU(PRVSPACE),%rax 275 addq $PC_PTI_STACK+PC_PTI_STACK_SZ*8,%rax 276 movq %rax,COMMON_TSS_RSP0(%rdx) 277 1: movl $TSSSEL,%eax 278 ltr %ax 279 jmp done_tss 280 281 do_ldt: movq PCPU(LDT),%rax 282 movq P_MD+MD_LDT_SD(%rcx),%rdx 283 movq %rdx,(%rax) 284 movq P_MD+MD_LDT_SD+8(%rcx),%rdx 285 movq %rdx,8(%rax) 286 movl $LDTSEL,%eax 287 jmp ld_ldt 288 END(cpu_switch) 289 290 /* 291 * savectx(pcb) 292 * Update pcb, saving current processor state. 293 */ 294 ENTRY(savectx) 295 /* Save caller's return address. */ 296 movq (%rsp),%rax 297 movq %rax,PCB_RIP(%rdi) 298 299 movq %rbx,PCB_RBX(%rdi) 300 movq %rsp,PCB_RSP(%rdi) 301 movq %rbp,PCB_RBP(%rdi) 302 movq %r12,PCB_R12(%rdi) 303 movq %r13,PCB_R13(%rdi) 304 movq %r14,PCB_R14(%rdi) 305 movq %r15,PCB_R15(%rdi) 306 307 movq %cr0,%rax 308 movq %rax,PCB_CR0(%rdi) 309 movq %cr2,%rax 310 movq %rax,PCB_CR2(%rdi) 311 movq %cr3,%rax 312 movq %rax,PCB_CR3(%rdi) 313 movq %cr4,%rax 314 movq %rax,PCB_CR4(%rdi) 315 316 movq %dr0,%rax 317 movq %rax,PCB_DR0(%rdi) 318 movq %dr1,%rax 319 movq %rax,PCB_DR1(%rdi) 320 movq %dr2,%rax 321 movq %rax,PCB_DR2(%rdi) 322 movq %dr3,%rax 323 movq %rax,PCB_DR3(%rdi) 324 movq %dr6,%rax 325 movq %rax,PCB_DR6(%rdi) 326 movq %dr7,%rax 327 movq %rax,PCB_DR7(%rdi) 328 329 movl $MSR_FSBASE,%ecx 330 rdmsr 331 movl %eax,PCB_FSBASE(%rdi) 332 movl %edx,PCB_FSBASE+4(%rdi) 333 movl $MSR_GSBASE,%ecx 334 rdmsr 335 movl %eax,PCB_GSBASE(%rdi) 336 movl %edx,PCB_GSBASE+4(%rdi) 337 movl $MSR_KGSBASE,%ecx 338 rdmsr 339 movl %eax,PCB_KGSBASE(%rdi) 340 movl %edx,PCB_KGSBASE+4(%rdi) 341 movl $MSR_EFER,%ecx 342 rdmsr 343 movl %eax,PCB_EFER(%rdi) 344 movl %edx,PCB_EFER+4(%rdi) 345 movl $MSR_STAR,%ecx 346 rdmsr 347 movl %eax,PCB_STAR(%rdi) 348 movl %edx,PCB_STAR+4(%rdi) 349 movl $MSR_LSTAR,%ecx 350 rdmsr 351 movl %eax,PCB_LSTAR(%rdi) 352 movl %edx,PCB_LSTAR+4(%rdi) 353 movl $MSR_CSTAR,%ecx 354 rdmsr 355 movl %eax,PCB_CSTAR(%rdi) 356 movl %edx,PCB_CSTAR+4(%rdi) 357 movl $MSR_SF_MASK,%ecx 358 rdmsr 359 movl %eax,PCB_SFMASK(%rdi) 360 movl %edx,PCB_SFMASK+4(%rdi) 361 362 sgdt PCB_GDT(%rdi) 363 sidt PCB_IDT(%rdi) 364 sldt PCB_LDT(%rdi) 365 str PCB_TR(%rdi) 366 367 movl $1,%eax 368 ret 369 END(savectx) 370 371 /* 372 * resumectx(pcb) 373 * Resuming processor state from pcb. 374 */ 375 ENTRY(resumectx) 376 /* Switch to KPML4phys. */ 377 movq KPML4phys,%rax 378 movq %rax,%cr3 379 380 /* Force kernel segment registers. */ 381 movl $KDSEL,%eax 382 movw %ax,%ds 383 movw %ax,%es 384 movw %ax,%ss 385 movl $KUF32SEL,%eax 386 movw %ax,%fs 387 movl $KUG32SEL,%eax 388 movw %ax,%gs 389 390 movl $MSR_FSBASE,%ecx 391 movl PCB_FSBASE(%rdi),%eax 392 movl 4 + PCB_FSBASE(%rdi),%edx 393 wrmsr 394 movl $MSR_GSBASE,%ecx 395 movl PCB_GSBASE(%rdi),%eax 396 movl 4 + PCB_GSBASE(%rdi),%edx 397 wrmsr 398 movl $MSR_KGSBASE,%ecx 399 movl PCB_KGSBASE(%rdi),%eax 400 movl 4 + PCB_KGSBASE(%rdi),%edx 401 wrmsr 402 403 /* Restore EFER one more time. */ 404 movl $MSR_EFER,%ecx 405 movl PCB_EFER(%rdi),%eax 406 wrmsr 407 408 /* Restore fast syscall stuff. */ 409 movl $MSR_STAR,%ecx 410 movl PCB_STAR(%rdi),%eax 411 movl 4 + PCB_STAR(%rdi),%edx 412 wrmsr 413 movl $MSR_LSTAR,%ecx 414 movl PCB_LSTAR(%rdi),%eax 415 movl 4 + PCB_LSTAR(%rdi),%edx 416 wrmsr 417 movl $MSR_CSTAR,%ecx 418 movl PCB_CSTAR(%rdi),%eax 419 movl 4 + PCB_CSTAR(%rdi),%edx 420 wrmsr 421 movl $MSR_SF_MASK,%ecx 422 movl PCB_SFMASK(%rdi),%eax 423 wrmsr 424 425 /* Restore CR0, CR2, CR4 and CR3. */ 426 movq PCB_CR0(%rdi),%rax 427 movq %rax,%cr0 428 movq PCB_CR2(%rdi),%rax 429 movq %rax,%cr2 430 movq PCB_CR4(%rdi),%rax 431 movq %rax,%cr4 432 movq PCB_CR3(%rdi),%rax 433 movq %rax,%cr3 434 435 /* Restore descriptor tables. */ 436 lidt PCB_IDT(%rdi) 437 lldt PCB_LDT(%rdi) 438 439 #define SDT_SYSTSS 9 440 #define SDT_SYSBSY 11 441 442 /* Clear "task busy" bit and reload TR. */ 443 movq PCPU(TSS),%rax 444 andb $(~SDT_SYSBSY | SDT_SYSTSS),5(%rax) 445 movw PCB_TR(%rdi),%ax 446 ltr %ax 447 448 #undef SDT_SYSTSS 449 #undef SDT_SYSBSY 450 451 /* Restore debug registers. */ 452 movq PCB_DR0(%rdi),%rax 453 movq %rax,%dr0 454 movq PCB_DR1(%rdi),%rax 455 movq %rax,%dr1 456 movq PCB_DR2(%rdi),%rax 457 movq %rax,%dr2 458 movq PCB_DR3(%rdi),%rax 459 movq %rax,%dr3 460 movq PCB_DR6(%rdi),%rax 461 movq %rax,%dr6 462 movq PCB_DR7(%rdi),%rax 463 movq %rax,%dr7 464 465 /* Restore other callee saved registers. */ 466 movq PCB_R15(%rdi),%r15 467 movq PCB_R14(%rdi),%r14 468 movq PCB_R13(%rdi),%r13 469 movq PCB_R12(%rdi),%r12 470 movq PCB_RBP(%rdi),%rbp 471 movq PCB_RSP(%rdi),%rsp 472 movq PCB_RBX(%rdi),%rbx 473 474 /* Restore return address. */ 475 movq PCB_RIP(%rdi),%rax 476 movq %rax,(%rsp) 477 478 xorl %eax,%eax 479 ret 480 END(resumectx)
Cache object: 14d0ba12d434a280aeb8de2392159054
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