kernel - Implement spectre mitigations part 2
[dragonfly.git] / sys / cpu / x86_64 / include / asmacros.h
1 /*
2  * Copyright (c) 1993 The Regents of the University of California.
3  * Copyright (c) 2008 The DragonFly Project.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  * $FreeBSD: src/sys/amd64/include/asmacros.h,v 1.32 2006/10/28 06:04:29 bde Exp $
31  */
32
33 #ifndef _CPU_ASMACROS_H_
34 #define _CPU_ASMACROS_H_
35
36 #include <sys/cdefs.h>
37 #include <machine/specialreg.h>
38
39 /* XXX too much duplication in various asm*.h's. */
40
41 /*
42  * CNAME is used to manage the relationship between symbol names in C
43  * and the equivalent assembly language names.  CNAME is given a name as
44  * it would be used in a C program.  It expands to the equivalent assembly
45  * language name.
46  */
47 #define CNAME(csym)             csym
48
49 #define ALIGN_DATA      .p2align 3      /* 8 byte alignment, zero filled */
50 #ifdef GPROF
51 #define ALIGN_TEXT      .p2align 4,0x90 /* 16-byte alignment, nop filled */
52 #else
53 #define ALIGN_TEXT      .p2align 4,0x90 /* 16-byte alignment, nop filled */
54 #endif
55 #define SUPERALIGN_TEXT .p2align 4,0x90 /* 16-byte alignment, nop filled */
56
57 #define GEN_ENTRY(name)         ALIGN_TEXT; .globl CNAME(name); \
58                                 .type CNAME(name),@function; CNAME(name):
59 #define NON_GPROF_ENTRY(name)   GEN_ENTRY(name)
60 #define NON_GPROF_RET           .byte 0xc3      /* opcode for `ret' */
61
62 #define END(name)               .size name, . - name
63
64 #ifdef GPROF
65 /*
66  * __mcount is like [.]mcount except that doesn't require its caller to set
67  * up a frame pointer.  It must be called before pushing anything onto the
68  * stack.  gcc should eventually generate code to call __mcount in most
69  * cases.  This would make -pg in combination with -fomit-frame-pointer
70  * useful.  gcc has a configuration variable PROFILE_BEFORE_PROLOGUE to
71  * allow profiling before setting up the frame pointer, but this is
72  * inadequate for good handling of special cases, e.g., -fpic works best
73  * with profiling after the prologue.
74  *
75  * [.]mexitcount is a new function to support non-statistical profiling if an
76  * accurate clock is available.  For C sources, calls to it are generated
77  * by the FreeBSD extension `-mprofiler-epilogue' to gcc.  It is best to
78  * call [.]mexitcount at the end of a function like the MEXITCOUNT macro does,
79  * but gcc currently generates calls to it at the start of the epilogue to
80  * avoid problems with -fpic.
81  *
82  * [.]mcount and __mcount may clobber the call-used registers and %ef.
83  * [.]mexitcount may clobber %ecx and %ef.
84  *
85  * Cross-jumping makes non-statistical profiling timing more complicated.
86  * It is handled in many cases by calling [.]mexitcount before jumping.  It
87  * is handled for conditional jumps using CROSSJUMP() and CROSSJUMP_LABEL().
88  * It is handled for some fault-handling jumps by not sharing the exit
89  * routine.
90  *
91  * ALTENTRY() must be before a corresponding ENTRY() so that it can jump to
92  * the main entry point.  Note that alt entries are counted twice.  They
93  * have to be counted as ordinary entries for gprof to get the call times
94  * right for the ordinary entries.
95  *
96  * High local labels are used in macros to avoid clashes with local labels
97  * in functions.
98  *
99  * Ordinary `ret' is used instead of a macro `RET' because there are a lot
100  * of `ret's.  0xc3 is the opcode for `ret' (`#define ret ... ret' can't
101  * be used because this file is sometimes preprocessed in traditional mode).
102  * `ret' clobbers eflags but this doesn't matter.
103  */
104 #define ALTENTRY(name)          GEN_ENTRY(name) ; MCOUNT ; MEXITCOUNT ; jmp 9f
105 #define CROSSJUMP(jtrue, label, jfalse) \
106         jfalse 8f; MEXITCOUNT; jmp __CONCAT(to,label); 8:
107 #define CROSSJUMPTARGET(label) \
108         ALIGN_TEXT; __CONCAT(to,label): ; MCOUNT; jmp label
109 #define ENTRY(name)             GEN_ENTRY(name) ; 9: ; MCOUNT
110 #define FAKE_MCOUNT(caller)     pushq caller ; call __mcount ; popq %rcx
111 #define MCOUNT                  call __mcount
112 #define MCOUNT_LABEL(name)      GEN_ENTRY(name) ; nop ; ALIGN_TEXT
113 #ifdef GUPROF
114 #define MEXITCOUNT              call .mexitcount
115 #define ret                     MEXITCOUNT ; NON_GPROF_RET
116 #else
117 #define MEXITCOUNT
118 #endif
119
120 #else /* !GPROF */
121 /*
122  * ALTENTRY() has to align because it is before a corresponding ENTRY().
123  * ENTRY() has to align to because there may be no ALTENTRY() before it.
124  * If there is a previous ALTENTRY() then the alignment code for ENTRY()
125  * is empty.
126  */
127 #define ALTENTRY(name)          GEN_ENTRY(name)
128 #define CROSSJUMP(jtrue, label, jfalse) jtrue label
129 #define CROSSJUMPTARGET(label)
130 #define ENTRY(name)             GEN_ENTRY(name)
131 #define FAKE_MCOUNT(caller)
132 #define MCOUNT
133 #define MCOUNT_LABEL(name)
134 #define MEXITCOUNT
135 #endif /* GPROF */
136
137 #ifdef LOCORE
138 /*
139  * Convenience macro for declaring interrupt entry points.
140  */
141 #define IDTVEC(name)    ALIGN_TEXT; .globl __CONCAT(X,name); \
142                         .type __CONCAT(X,name),@function; __CONCAT(X,name):
143
144 /*
145  * stack frame macro support - supports mmu isolation, swapgs, and
146  * stack frame pushing and popping.
147  */
148
149 /*
150  * Kernel pmap isolation to work-around the massive Intel mmu bug
151  * that allows kernel memory to be sussed out due to speculative memory
152  * reads and instruction execution creating timing differences that can
153  * be detected by userland.  e.g. force speculative read, speculatively
154  * execute a cmp/branch sequence, detect timing.  Iterate cmp $values
155  * to suss-out content of speculatively read kernel memory.
156  *
157  * We do this by creating a trampoline area for all user->kernel and
158  * kernel->user transitions.  The trampoline area allows us to limit
159  * the reach the kernel map in the isolated version of the user pmap
160  * to JUST the trampoline area (for all cpus), tss, and vector area.
161  *
162  * It is very important that these transitions not access any memory
163  * outside of the trampoline page while the isolated user process pmap
164  * is active in %cr3.
165  *
166  * The trampoline does not add much overhead when pmap isolation is
167  * disabled, so we just run with it regardless.  Of course, when pmap
168  * isolation is enabled, the %cr3 loads add 150-250ns to every system
169  * call as well as (without PCID) smash the TLB.
170  *
171  * KMMUENTER -  Executed by the trampoline when a user->kernel transition
172  *              is detected.  The stack pointer points into the pcpu
173  *              trampoline space and is available for register save/restore.
174  *              Other registers have not yet been saved.  %gs points at
175  *              the kernel pcpu structure.
176  *
177  *              Caller has already determined that a transition is in
178  *              progress and has already issued the swapgs.  hwtf indicates
179  *              how much hardware has already pushed.
180  *
181  * KMMUEXIT  -  Executed when a kernel->user transition is made.  The stack
182  *              pointer points into the pcpu trampoline space and we are
183  *              almost ready to iretq.  %gs still points at the kernel pcpu
184  *              structure.
185  *
186  *              Caller has already determined that a transition is in
187  *              progress.  hwtf indicates how much hardware has already
188  *              pushed.
189  */
190
191 /*
192  * KMMUENTER_CORE - Handles ISOMMU, IBRS, and IBPB.  Caller has already
193  *                  saved %rcx and %rdx.  We have to deal with %rax.
194  *
195  *                  XXX If IBPB is not supported, try to clear the
196  *                  call return hw cache w/ many x chained call sequence?
197  *
198  *      IBRS2 note - We are leaving IBRS on full-time.  However, Intel
199  *      believes it is not safe unless the MSR is poked on each user->kernel
200  *      transition, so poke the MSR for both IBRS1 and IBRS2.
201  */
202 #define KMMUENTER_CORE                                                  \
203         testq   $PCB_ISOMMU,PCPU(trampoline)+TR_PCB_FLAGS ;             \
204         je      40f ;                                                   \
205         movq    PCPU(trampoline)+TR_PCB_CR3,%rcx ;                      \
206         movq    %rcx,%cr3 ;                                             \
207 40:     testq   $PCB_IBRS1|PCB_IBRS2|PCB_IBPB,PCPU(trampoline)+TR_PCB_GFLAGS ;\
208         je      43f ;                                                   \
209         movq    %rax, TR_RAX(%rsp) ;                                    \
210         testq   $PCB_IBRS1|PCB_IBRS2,PCPU(trampoline)+TR_PCB_GFLAGS ;   \
211         je      41f ;                                                   \
212         movl    $MSR_SPEC_CTRL,%ecx ;                                   \
213         movl    $MSR_IBRS_ENABLE,%eax ;                                 \
214         xorl    %edx,%edx ;                                             \
215         wrmsr ;                                                         \
216 41:     testq   $PCB_IBPB,PCPU(trampoline)+TR_PCB_GFLAGS ;              \
217         je      42f ;                                                   \
218         movl    $MSR_PRED_CMD,%ecx ;                                    \
219         movl    $MSR_IBPB_BARRIER,%eax ;                                \
220         xorl    %edx,%edx ;                                             \
221         wrmsr ;                                                         \
222 42:     movq    TR_RAX(%rsp), %rax ;                                    \
223 43:                                                                     \
224
225
226 /*
227  * Enter with trampoline, hardware pushed up to %rip
228  */
229 #define KMMUENTER_TFRIP                                                 \
230         subq    $TR_RIP, %rsp ;                                         \
231         movq    %rcx, TR_RCX(%rsp) ;                                    \
232         movq    %rdx, TR_RDX(%rsp) ;                                    \
233         KMMUENTER_CORE ;                                                \
234         movq    %rsp, %rcx ;            /* trampoline rsp */            \
235         movq    PCPU(trampoline)+TR_PCB_RSP,%rsp ; /* kstack rsp */     \
236         movq    TR_SS(%rcx), %rdx ;                                     \
237         pushq   %rdx ;                                                  \
238         movq    TR_RSP(%rcx), %rdx ;                                    \
239         pushq   %rdx ;                                                  \
240         movq    TR_RFLAGS(%rcx), %rdx ;                                 \
241         pushq   %rdx ;                                                  \
242         movq    TR_CS(%rcx), %rdx ;                                     \
243         pushq   %rdx ;                                                  \
244         movq    TR_RIP(%rcx), %rdx ;                                    \
245         pushq   %rdx ;                                                  \
246         movq    TR_RDX(%rcx), %rdx ;                                    \
247         movq    TR_RCX(%rcx), %rcx                                      \
248
249 /*
250  * Enter with trampoline, hardware pushed up to ERR
251  */
252 #define KMMUENTER_TFERR                                                 \
253         subq    $TR_ERR, %rsp ;                                         \
254         movq    %rcx, TR_RCX(%rsp) ;                                    \
255         movq    %rdx, TR_RDX(%rsp) ;                                    \
256         KMMUENTER_CORE ;                                                \
257         movq    %rsp, %rcx ;            /* trampoline rsp */            \
258         movq    PCPU(trampoline)+TR_PCB_RSP,%rsp ; /* kstack rsp */     \
259         movq    TR_SS(%rcx), %rdx ;                                     \
260         pushq   %rdx ;                                                  \
261         movq    TR_RSP(%rcx), %rdx ;                                    \
262         pushq   %rdx ;                                                  \
263         movq    TR_RFLAGS(%rcx), %rdx ;                                 \
264         pushq   %rdx ;                                                  \
265         movq    TR_CS(%rcx), %rdx ;                                     \
266         pushq   %rdx ;                                                  \
267         movq    TR_RIP(%rcx), %rdx ;                                    \
268         pushq   %rdx ;                                                  \
269         movq    TR_ERR(%rcx), %rdx ;                                    \
270         pushq   %rdx ;                                                  \
271         movq    TR_RDX(%rcx), %rdx ;                                    \
272         movq    TR_RCX(%rcx), %rcx                                      \
273
274 /*
275  * Enter with trampoline, hardware pushed up to ERR and
276  * we need to save %cr2 early (before potentially reloading %cr3).
277  */
278 #define KMMUENTER_TFERR_SAVECR2                                         \
279         subq    $TR_ERR, %rsp ;                                         \
280         movq    %rcx, TR_RCX(%rsp) ;                                    \
281         movq    %rdx, TR_RDX(%rsp) ;                                    \
282         movq    %cr2, %rcx ;                                            \
283         movq    %rcx, PCPU(trampoline)+TR_CR2 ;                         \
284         KMMUENTER_CORE ;                                                \
285         movq    %rsp, %rcx ;            /* trampoline rsp */            \
286         movq    PCPU(trampoline)+TR_PCB_RSP,%rsp ; /* kstack rsp */     \
287         movq    TR_SS(%rcx), %rdx ;                                     \
288         pushq   %rdx ;                                                  \
289         movq    TR_RSP(%rcx), %rdx ;                                    \
290         pushq   %rdx ;                                                  \
291         movq    TR_RFLAGS(%rcx), %rdx ;                                 \
292         pushq   %rdx ;                                                  \
293         movq    TR_CS(%rcx), %rdx ;                                     \
294         pushq   %rdx ;                                                  \
295         movq    TR_RIP(%rcx), %rdx ;                                    \
296         pushq   %rdx ;                                                  \
297         movq    TR_ERR(%rcx), %rdx ;                                    \
298         pushq   %rdx ;                                                  \
299         movq    TR_RDX(%rcx), %rdx ;                                    \
300         movq    TR_RCX(%rcx), %rcx                                      \
301
302 /*
303  * Set %cr3 if necessary on syscall entry.  No registers may be
304  * disturbed.
305  *
306  * NOTE: TR_CR2 is used by the caller to save %rsp, we cannot use it here.
307  */
308 #define KMMUENTER_SYSCALL                                               \
309         movq    %rcx, PCPU(trampoline)+TR_RCX ;                         \
310         movq    %rdx, PCPU(trampoline)+TR_RDX ;                         \
311         KMMUENTER_CORE ;                                                \
312         movq    PCPU(trampoline)+TR_RDX, %rdx ;                         \
313         movq    PCPU(trampoline)+TR_RCX, %rcx                           \
314
315 /*
316  * KMMUEXIT_CORE handles IBRS and IBPB, but not ISOMMU
317  *
318  * We don't re-execute the IBPB barrier on exit atm.
319  */
320 #define KMMUEXIT_CORE                                                   \
321         testq   $PCB_IBRS1,PCPU(trampoline)+TR_PCB_GFLAGS ;             \
322         je      41f ;                                                   \
323         movq    %rax, PCPU(trampoline)+TR_RAX ;                         \
324         movq    %rcx, PCPU(trampoline)+TR_RCX ;                         \
325         movq    %rdx, PCPU(trampoline)+TR_RDX ;                         \
326         movl    $MSR_SPEC_CTRL,%ecx ;                                   \
327         movl    $MSR_IBRS_DISABLE,%eax ;                                \
328         xorl    %edx,%edx ;                                             \
329         wrmsr ;                                                         \
330         movq    PCPU(trampoline)+TR_RDX, %rdx ;                         \
331         movq    PCPU(trampoline)+TR_RCX, %rcx ;                         \
332         movq    PCPU(trampoline)+TR_RAX, %rax ;                         \
333 41:
334
335 /*
336  * We are positioned at the base of the trapframe.  Advance the trapframe
337  * and handle MMU isolation.  MMU isolation requires us to copy the
338  * hardware frame to the trampoline area before setting %cr3 to the
339  * isolated map.  We then set the %rsp for iretq to TR_RIP in the
340  * trampoline area (after restoring the register we saved in TR_ERR).
341  */
342 #define KMMUEXIT                                                        \
343         addq    $TF_RIP,%rsp ;                                          \
344         KMMUEXIT_CORE ;                                                 \
345         testq   $PCB_ISOMMU,PCPU(trampoline)+TR_PCB_FLAGS ;             \
346         je      40f ;                                                   \
347         movq    %rcx, PCPU(trampoline)+TR_ERR ; /* save in TR_ERR */    \
348         popq    %rcx ;                          /* copy %rip */         \
349         movq    %rcx, PCPU(trampoline)+TR_RIP ;                         \
350         popq    %rcx ;                          /* copy %cs */          \
351         movq    %rcx, PCPU(trampoline)+TR_CS ;                          \
352         popq    %rcx ;                          /* copy %rflags */      \
353         movq    %rcx, PCPU(trampoline)+TR_RFLAGS ;                      \
354         popq    %rcx ;                          /* copy %rsp */         \
355         movq    %rcx, PCPU(trampoline)+TR_RSP ;                         \
356         popq    %rcx ;                          /* copy %ss */          \
357         movq    %rcx, PCPU(trampoline)+TR_SS ;                          \
358         movq    %gs:0,%rcx ;                                            \
359         addq    $GD_TRAMPOLINE+TR_ERR,%rcx ;                            \
360         movq    %rcx,%rsp ;                                             \
361         movq    PCPU(trampoline)+TR_PCB_CR3_ISO,%rcx ;                  \
362         movq    %rcx,%cr3 ;                                             \
363         popq    %rcx ;          /* positioned at TR_RIP after this */   \
364 40:                                                                     \
365
366 /*
367  * Warning: user stack pointer already loaded into %rsp at this
368  * point.  We still have the kernel %gs.
369  *
370  * Caller will sysexit, we do not have to copy anything to the
371  * trampoline area.
372  */
373 #define KMMUEXIT_SYSCALL                                                \
374         KMMUEXIT_CORE ;                                                 \
375         testq   $PCB_ISOMMU,PCPU(trampoline)+TR_PCB_FLAGS ;             \
376         je      40f ;                                                   \
377         movq    %rcx, PCPU(trampoline)+TR_RCX ;                         \
378         movq    PCPU(trampoline)+TR_PCB_CR3_ISO,%rcx ;                  \
379         movq    %rcx,%cr3 ;                                             \
380         movq    PCPU(trampoline)+TR_RCX, %rcx ;                         \
381 40:                                                                     \
382
383 /*
384  * Macros to create and destroy a trap frame.  rsp has already been shifted
385  * to the base of the trapframe in the thread structure.
386  */
387 #define PUSH_FRAME_REGS                                                 \
388         movq    %rdi,TF_RDI(%rsp) ;                                     \
389         movq    %rsi,TF_RSI(%rsp) ;                                     \
390         movq    %rdx,TF_RDX(%rsp) ;                                     \
391         movq    %rcx,TF_RCX(%rsp) ;                                     \
392         movq    %r8,TF_R8(%rsp) ;                                       \
393         movq    %r9,TF_R9(%rsp) ;                                       \
394         movq    %rax,TF_RAX(%rsp) ;                                     \
395         movq    %rbx,TF_RBX(%rsp) ;                                     \
396         movq    %rbp,TF_RBP(%rsp) ;                                     \
397         movq    %r10,TF_R10(%rsp) ;                                     \
398         movq    %r11,TF_R11(%rsp) ;                                     \
399         movq    %r12,TF_R12(%rsp) ;                                     \
400         movq    %r13,TF_R13(%rsp) ;                                     \
401         movq    %r14,TF_R14(%rsp) ;                                     \
402         movq    %r15,TF_R15(%rsp)
403
404 /*
405  * PUSH_FRAME is the first thing executed upon interrupt entry.  We are
406  * responsible for swapgs execution and the KMMUENTER dispatch.
407  */
408 #define PUSH_FRAME_TFRIP                                                \
409         testb   $SEL_RPL_MASK,TF_CS-TF_RIP(%rsp) ; /* from userland? */ \
410         jz      1f ;                                                    \
411         swapgs ;                /* from userland */                     \
412         KMMUENTER_TFRIP ;       /* from userland */                     \
413 1:                                                                      \
414         subq    $TF_RIP,%rsp ;                                          \
415         PUSH_FRAME_REGS                                                 \
416
417 #define PUSH_FRAME_TFERR                                                \
418         testb   $SEL_RPL_MASK,TF_CS-TF_ERR(%rsp) ; /* from userland? */ \
419         jz      1f ;                                                    \
420         swapgs ;                /* from userland */                     \
421         KMMUENTER_TFERR ;       /* from userland */                     \
422 1:                                                                      \
423         subq    $TF_ERR,%rsp ;                                          \
424         PUSH_FRAME_REGS                                                 \
425
426 #define PUSH_FRAME_TFERR_SAVECR2                                        \
427         testb   $SEL_RPL_MASK,TF_CS-TF_ERR(%rsp) ;                      \
428         jz      1f ;                                                    \
429         swapgs ;                /* from userland */                     \
430         KMMUENTER_TFERR_SAVECR2 ;/* from userland */                    \
431         subq    $TF_ERR,%rsp ;                                          \
432         PUSH_FRAME_REGS ;                                               \
433         movq    PCPU(trampoline)+TR_CR2, %r10 ;                         \
434         jmp 2f ;                                                        \
435 1:                                                                      \
436         subq    $TF_ERR,%rsp ;                                          \
437         PUSH_FRAME_REGS ;                                               \
438         movq    %cr2, %r10 ;                                            \
439 2:                                                                      \
440         movq    %r10, TF_ADDR(%rsp)
441
442 /*
443  * POP_FRAME is issued just prior to the iretq, or just prior to a
444  * jmp doreti_iret.  These must be passed in to the macro.
445  */
446 #define POP_FRAME(lastinsn)                                             \
447         movq    TF_RDI(%rsp),%rdi ;                                     \
448         movq    TF_RSI(%rsp),%rsi ;                                     \
449         movq    TF_RDX(%rsp),%rdx ;                                     \
450         movq    TF_RCX(%rsp),%rcx ;                                     \
451         movq    TF_R8(%rsp),%r8 ;                                       \
452         movq    TF_R9(%rsp),%r9 ;                                       \
453         movq    TF_RAX(%rsp),%rax ;                                     \
454         movq    TF_RBX(%rsp),%rbx ;                                     \
455         movq    TF_RBP(%rsp),%rbp ;                                     \
456         movq    TF_R10(%rsp),%r10 ;                                     \
457         movq    TF_R11(%rsp),%r11 ;                                     \
458         movq    TF_R12(%rsp),%r12 ;                                     \
459         movq    TF_R13(%rsp),%r13 ;                                     \
460         movq    TF_R14(%rsp),%r14 ;                                     \
461         movq    TF_R15(%rsp),%r15 ;                                     \
462         cli ;                                                           \
463         testb   $SEL_RPL_MASK,TF_CS(%rsp) ; /* return to user? */       \
464         jz      1f ;                                                    \
465         KMMUEXIT ;              /* return to user */                    \
466         swapgs ;                /* return to user */                    \
467         jmp     2f ;                                                    \
468 1:                                                                      \
469         addq    $TF_RIP,%rsp ;  /* setup for iretq */                   \
470 2:                                                                      \
471         lastinsn
472
473 /*
474  * Access per-CPU data.
475  */
476 #define PCPU(member)            %gs:gd_ ## member
477 #define PCPU_E8(member,idx)     %gs:gd_ ## member(,idx,8)
478 #define PCPU_ADDR(member, reg)                                  \
479         movq %gs:PC_PRVSPACE, reg ;                             \
480         addq $PC_ ## member, reg
481
482 #endif /* LOCORE */
483
484 #endif /* !_CPU_ASMACROS_H_ */