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: stable/11/sys/amd64/amd64/cpu_switch.S 361561 2020-05-27 18:55:24Z kib $ 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 */ 71ENTRY(cpu_throw) 72 movq %rsi,%r12 73 movq %rsi,%rdi 74 call pmap_activate_sw 75 jmp sw1 76END(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 */ 87ENTRY(cpu_switch) 88 /* Switch to new thread. First, save context. */ 89 movq TD_PCB(%rdi),%r8 90 91 movq (%rsp),%rax /* Hardware registers */ 92 movq %r15,PCB_R15(%r8) 93 movq %r14,PCB_R14(%r8) 94 movq %r13,PCB_R13(%r8) 95 movq %r12,PCB_R12(%r8) 96 movq %rbp,PCB_RBP(%r8) 97 movq %rsp,PCB_RSP(%r8) 98 movq %rbx,PCB_RBX(%r8) 99 movq %rax,PCB_RIP(%r8) 100 101 testl $PCB_FULL_IRET,PCB_FLAGS(%r8) 102 jnz 2f 103 orl $PCB_FULL_IRET,PCB_FLAGS(%r8) 104 testl $TDP_KTHREAD,TD_PFLAGS(%rdi) 105 jnz 2f 106 testb $CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip) 107 jz 2f 108 movl %fs,%eax 109 cmpl $KUF32SEL,%eax 110 jne 1f 111 rdfsbase %rax 112 movq %rax,PCB_FSBASE(%r8) 1131: movl %gs,%eax 114 cmpl $KUG32SEL,%eax 115 jne 2f 116 movq %rdx,%r12 117 movl $MSR_KGSBASE,%ecx /* Read user gs base */ 118 rdmsr 119 shlq $32,%rdx 120 orq %rdx,%rax 121 movq %rax,PCB_GSBASE(%r8) 122 movq %r12,%rdx 123 1242: 125 testl $PCB_DBREGS,PCB_FLAGS(%r8) 126 jnz store_dr /* static predict not taken */ 127done_store_dr: 128 129 /* have we used fp, and need a save? */ 130 cmpq %rdi,PCPU(FPCURTHREAD) 131 jne 2f 132 movq PCB_SAVEFPU(%r8),%r8 133 clts 134 cmpl $0,use_xsave(%rip) 135 jne 1f 136 fxsave (%r8) 137 jmp 2f 1381: movq %rdx,%rcx 139 movl xsave_mask,%eax 140 movl xsave_mask+4,%edx 141 .globl ctx_switch_xsave 142ctx_switch_xsave: 143 /* This is patched to xsaveopt if supported, see fpuinit_bsp1() */ 144 xsave (%r8) 145 movq %rcx,%rdx 1462: 147 /* Save is done. Now fire up new thread. Leave old vmspace. */ 148 movq %rsi,%r12 149 movq %rdi,%r13 150 movq %rdx,%r15 151 movq %rsi,%rdi 152 callq pmap_activate_sw 153 SETLK %r15,TD_LOCK(%r13) /* Release the old thread */ 154sw1: 155 movq TD_PCB(%r12),%r8 156#if defined(SCHED_ULE) && defined(SMP) 157 /* Wait for the new thread to become unblocked */ 158 movq $blocked_lock, %rdx 1591: 160 movq TD_LOCK(%r12),%rcx 161 cmpq %rcx, %rdx 162 pause 163 je 1b 164#endif 165 /* 166 * At this point, we've switched address spaces and are ready 167 * to load up the rest of the next context. 168 */ 169 170 /* Skip loading LDT and user fsbase/gsbase for kthreads */ 171 testl $TDP_KTHREAD,TD_PFLAGS(%r12) 172 jnz do_kthread 173 174 /* 175 * Load ldt register 176 */ 177 movq TD_PROC(%r12),%rcx 178 cmpq $0, P_MD+MD_LDT(%rcx) 179 jne do_ldt 180 xorl %eax,%eax 181ld_ldt: lldt %ax 182 183 /* Restore fs base in GDT */ 184 movl PCB_FSBASE(%r8),%eax 185 movq PCPU(FS32P),%rdx 186 movw %ax,2(%rdx) 187 shrl $16,%eax 188 movb %al,4(%rdx) 189 shrl $8,%eax 190 movb %al,7(%rdx) 191 192 /* Restore gs base in GDT */ 193 movl PCB_GSBASE(%r8),%eax 194 movq PCPU(GS32P),%rdx 195 movw %ax,2(%rdx) 196 shrl $16,%eax 197 movb %al,4(%rdx) 198 shrl $8,%eax 199 movb %al,7(%rdx) 200 201do_kthread: 202 /* Do we need to reload tss ? */ 203 movq PCPU(TSSP),%rax 204 movq PCB_TSSP(%r8),%rdx 205 testq %rdx,%rdx 206 cmovzq PCPU(COMMONTSSP),%rdx 207 cmpq %rax,%rdx 208 jne do_tss 209done_tss: 210 movq %r8,PCPU(RSP0) 211 movq %r8,PCPU(CURPCB) 212 /* Update the TSS_RSP0 pointer for the next interrupt */ 213 cmpq $~0,PCPU(UCR3) 214 je 1f 215 movq PCPU(PTI_RSP0),%rax 216 movq %rax,TSS_RSP0(%rdx) 217 jmp 2f 2181: movq %r8,TSS_RSP0(%rdx) 2192: movq %r12,PCPU(CURTHREAD) /* into next thread */ 220 221 /* Test if debug registers should be restored. */ 222 testl $PCB_DBREGS,PCB_FLAGS(%r8) 223 jnz load_dr /* static predict not taken */ 224done_load_dr: 225 226 /* Restore context. */ 227 movq PCB_R15(%r8),%r15 228 movq PCB_R14(%r8),%r14 229 movq PCB_R13(%r8),%r13 230 movq PCB_R12(%r8),%r12 231 movq PCB_RBP(%r8),%rbp 232 movq PCB_RSP(%r8),%rsp 233 movq PCB_RBX(%r8),%rbx 234 movq PCB_RIP(%r8),%rax 235 movq %rax,(%rsp) 236 movq PCPU(CURTHREAD),%rdi 237 call fpu_activate_sw 238 cmpb $0,cpu_flush_rsb_ctxsw(%rip) 239 jne rsb_flush 240 ret 241 242 /* 243 * We order these strangely for several reasons. 244 * 1: I wanted to use static branch prediction hints 245 * 2: Most athlon64/opteron cpus don't have them. They define 246 * a forward branch as 'predict not taken'. Intel cores have 247 * the 'rep' prefix to invert this. 248 * So, to make it work on both forms of cpu we do the detour. 249 * We use jumps rather than call in order to avoid the stack. 250 */ 251 252store_dr: 253 movq %dr7,%rax /* yes, do the save */ 254 movq %dr0,%r15 255 movq %dr1,%r14 256 movq %dr2,%r13 257 movq %dr3,%r12 258 movq %dr6,%r11 259 movq %r15,PCB_DR0(%r8) 260 movq %r14,PCB_DR1(%r8) 261 movq %r13,PCB_DR2(%r8) 262 movq %r12,PCB_DR3(%r8) 263 movq %r11,PCB_DR6(%r8) 264 movq %rax,PCB_DR7(%r8) 265 andq $0x0000fc00, %rax /* disable all watchpoints */ 266 movq %rax,%dr7 267 jmp done_store_dr 268 269load_dr: 270 movq %dr7,%rax 271 movq PCB_DR0(%r8),%r15 272 movq PCB_DR1(%r8),%r14 273 movq PCB_DR2(%r8),%r13 274 movq PCB_DR3(%r8),%r12 275 movq PCB_DR6(%r8),%r11 276 movq PCB_DR7(%r8),%rcx 277 movq %r15,%dr0 278 movq %r14,%dr1 279 /* Preserve reserved bits in %dr7 */ 280 andq $0x0000fc00,%rax 281 andq $~0x0000fc00,%rcx 282 movq %r13,%dr2 283 movq %r12,%dr3 284 orq %rcx,%rax 285 movq %r11,%dr6 286 movq %rax,%dr7 287 jmp done_load_dr 288 289do_tss: movq %rdx,PCPU(TSSP) 290 movq %rdx,%rcx 291 movq PCPU(TSS),%rax 292 movw %cx,2(%rax) 293 shrq $16,%rcx 294 movb %cl,4(%rax) 295 shrq $8,%rcx 296 movb %cl,7(%rax) 297 shrq $8,%rcx 298 movl %ecx,8(%rax) 299 movb $0x89,5(%rax) /* unset busy */ 300 movl $TSSSEL,%eax 301 ltr %ax 302 jmp done_tss 303 304do_ldt: movq PCPU(LDT),%rax 305 movq P_MD+MD_LDT_SD(%rcx),%rdx 306 movq %rdx,(%rax) 307 movq P_MD+MD_LDT_SD+8(%rcx),%rdx 308 movq %rdx,8(%rax) 309 movl $LDTSEL,%eax 310 jmp ld_ldt 311END(cpu_switch) 312 313/* 314 * savectx(pcb) 315 * Update pcb, saving current processor state. 316 */ 317ENTRY(savectx) 318 /* Save caller's return address. */ 319 movq (%rsp),%rax 320 movq %rax,PCB_RIP(%rdi) 321 322 movq %rbx,PCB_RBX(%rdi) 323 movq %rsp,PCB_RSP(%rdi) 324 movq %rbp,PCB_RBP(%rdi) 325 movq %r12,PCB_R12(%rdi) 326 movq %r13,PCB_R13(%rdi) 327 movq %r14,PCB_R14(%rdi) 328 movq %r15,PCB_R15(%rdi) 329 330 movq %cr0,%rax 331 movq %rax,PCB_CR0(%rdi) 332 movq %cr2,%rax 333 movq %rax,PCB_CR2(%rdi) 334 movq %cr3,%rax 335 movq %rax,PCB_CR3(%rdi) 336 movq %cr4,%rax 337 movq %rax,PCB_CR4(%rdi) 338 339 movq %dr0,%rax 340 movq %rax,PCB_DR0(%rdi) 341 movq %dr1,%rax 342 movq %rax,PCB_DR1(%rdi) 343 movq %dr2,%rax 344 movq %rax,PCB_DR2(%rdi) 345 movq %dr3,%rax 346 movq %rax,PCB_DR3(%rdi) 347 movq %dr6,%rax 348 movq %rax,PCB_DR6(%rdi) 349 movq %dr7,%rax 350 movq %rax,PCB_DR7(%rdi) 351 352 movl $MSR_FSBASE,%ecx 353 rdmsr 354 movl %eax,PCB_FSBASE(%rdi) 355 movl %edx,PCB_FSBASE+4(%rdi) 356 movl $MSR_GSBASE,%ecx 357 rdmsr 358 movl %eax,PCB_GSBASE(%rdi) 359 movl %edx,PCB_GSBASE+4(%rdi) 360 movl $MSR_KGSBASE,%ecx 361 rdmsr 362 movl %eax,PCB_KGSBASE(%rdi) 363 movl %edx,PCB_KGSBASE+4(%rdi) 364 movl $MSR_EFER,%ecx 365 rdmsr 366 movl %eax,PCB_EFER(%rdi) 367 movl %edx,PCB_EFER+4(%rdi) 368 movl $MSR_STAR,%ecx 369 rdmsr 370 movl %eax,PCB_STAR(%rdi) 371 movl %edx,PCB_STAR+4(%rdi) 372 movl $MSR_LSTAR,%ecx 373 rdmsr 374 movl %eax,PCB_LSTAR(%rdi) 375 movl %edx,PCB_LSTAR+4(%rdi) 376 movl $MSR_CSTAR,%ecx 377 rdmsr 378 movl %eax,PCB_CSTAR(%rdi) 379 movl %edx,PCB_CSTAR+4(%rdi) 380 movl $MSR_SF_MASK,%ecx 381 rdmsr 382 movl %eax,PCB_SFMASK(%rdi) 383 movl %edx,PCB_SFMASK+4(%rdi) 384 385 sgdt PCB_GDT(%rdi) 386 sidt PCB_IDT(%rdi) 387 sldt PCB_LDT(%rdi) 388 str PCB_TR(%rdi) 389 390 movl $1,%eax 391 ret 392END(savectx) 393 394/* 395 * resumectx(pcb) 396 * Resuming processor state from pcb. 397 */ 398ENTRY(resumectx) 399 /* Switch to KPML4phys. */ 400 movq KPML4phys,%rax 401 movq %rax,%cr3 402 403 /* Force kernel segment registers. */ 404 movl $KDSEL,%eax 405 movw %ax,%ds 406 movw %ax,%es 407 movw %ax,%ss 408 movl $KUF32SEL,%eax 409 movw %ax,%fs 410 movl $KUG32SEL,%eax 411 movw %ax,%gs 412 413 movl $MSR_FSBASE,%ecx 414 movl PCB_FSBASE(%rdi),%eax 415 movl 4 + PCB_FSBASE(%rdi),%edx 416 wrmsr 417 movl $MSR_GSBASE,%ecx 418 movl PCB_GSBASE(%rdi),%eax 419 movl 4 + PCB_GSBASE(%rdi),%edx 420 wrmsr 421 movl $MSR_KGSBASE,%ecx 422 movl PCB_KGSBASE(%rdi),%eax 423 movl 4 + PCB_KGSBASE(%rdi),%edx 424 wrmsr 425 426 /* Restore EFER one more time. */ 427 movl $MSR_EFER,%ecx 428 movl PCB_EFER(%rdi),%eax 429 wrmsr 430 431 /* Restore fast syscall stuff. */ 432 movl $MSR_STAR,%ecx 433 movl PCB_STAR(%rdi),%eax 434 movl 4 + PCB_STAR(%rdi),%edx 435 wrmsr 436 movl $MSR_LSTAR,%ecx 437 movl PCB_LSTAR(%rdi),%eax 438 movl 4 + PCB_LSTAR(%rdi),%edx 439 wrmsr 440 movl $MSR_CSTAR,%ecx 441 movl PCB_CSTAR(%rdi),%eax 442 movl 4 + PCB_CSTAR(%rdi),%edx 443 wrmsr 444 movl $MSR_SF_MASK,%ecx 445 movl PCB_SFMASK(%rdi),%eax 446 wrmsr 447 448 /* Restore CR0, CR2, CR4 and CR3. */ 449 movq PCB_CR0(%rdi),%rax 450 movq %rax,%cr0 451 movq PCB_CR2(%rdi),%rax 452 movq %rax,%cr2 453 movq PCB_CR4(%rdi),%rax 454 movq %rax,%cr4 455 movq PCB_CR3(%rdi),%rax 456 movq %rax,%cr3 457 458 /* Restore descriptor tables. */ 459 lidt PCB_IDT(%rdi) 460 lldt PCB_LDT(%rdi) 461 462#define SDT_SYSTSS 9 463#define SDT_SYSBSY 11 464 465 /* Clear "task busy" bit and reload TR. */ 466 movq PCPU(TSS),%rax 467 andb $(~SDT_SYSBSY | SDT_SYSTSS),5(%rax) 468 movw PCB_TR(%rdi),%ax 469 ltr %ax 470 471#undef SDT_SYSTSS 472#undef SDT_SYSBSY 473 474 /* Restore debug registers. */ 475 movq PCB_DR0(%rdi),%rax 476 movq %rax,%dr0 477 movq PCB_DR1(%rdi),%rax 478 movq %rax,%dr1 479 movq PCB_DR2(%rdi),%rax 480 movq %rax,%dr2 481 movq PCB_DR3(%rdi),%rax 482 movq %rax,%dr3 483 movq PCB_DR6(%rdi),%rax 484 movq %rax,%dr6 485 movq PCB_DR7(%rdi),%rax 486 movq %rax,%dr7 487 488 /* Restore other callee saved registers. */ 489 movq PCB_R15(%rdi),%r15 490 movq PCB_R14(%rdi),%r14 491 movq PCB_R13(%rdi),%r13 492 movq PCB_R12(%rdi),%r12 493 movq PCB_RBP(%rdi),%rbp 494 movq PCB_RSP(%rdi),%rsp 495 movq PCB_RBX(%rdi),%rbx 496 497 /* Restore return address. */ 498 movq PCB_RIP(%rdi),%rax 499 movq %rax,(%rsp) 500 501 xorl %eax,%eax 502 ret 503END(resumectx) 504