| blob | 1333d9851778ab282c3cc7a282ec9368c1e26035 |
1 /*
2 * linux/arch/x86_64/entry.S
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
6 * Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
7 */
9 /*
10 * entry.S contains the system-call and fault low-level handling routines.
11 *
12 * Some of this is documented in Documentation/x86/entry_64.txt
13 *
14 * NOTE: This code handles signal-recognition, which happens every time
15 * after an interrupt and after each system call.
16 *
17 * Normal syscalls and interrupts don't save a full stack frame, this is
18 * only done for syscall tracing, signals or fork/exec et.al.
19 *
20 * A note on terminology:
21 * - top of stack: Architecture defined interrupt frame from SS to RIP
22 * at the top of the kernel process stack.
23 * - partial stack frame: partially saved registers up to R11.
24 * - full stack frame: Like partial stack frame, but all register saved.
25 *
26 * Some macro usage:
27 * - CFI macros are used to generate dwarf2 unwind information for better
28 * backtraces. They don't change any code.
29 * - SAVE_ALL/RESTORE_ALL - Save/restore all registers
30 * - SAVE_ARGS/RESTORE_ARGS - Save/restore registers that C functions modify.
31 * There are unfortunately lots of special cases where some registers
32 * not touched. The macro is a big mess that should be cleaned up.
33 * - SAVE_REST/RESTORE_REST - Handle the registers not saved by SAVE_ARGS.
34 * Gives a full stack frame.
35 * - ENTRY/END Define functions in the symbol table.
36 * - FIXUP_TOP_OF_STACK/RESTORE_TOP_OF_STACK - Fix up the hardware stack
37 * frame that is otherwise undefined after a SYSCALL
38 * - TRACE_IRQ_* - Trace hard interrupt state for lock debugging.
39 * - errorentry/paranoidentry/zeroentry - Define exception entry points.
40 */
42 #include <linux/linkage.h>
43 #include <asm/segment.h>
44 #include <asm/cache.h>
45 #include <asm/errno.h>
46 #include <asm/dwarf2.h>
47 #include <asm/calling.h>
48 #include <asm/asm-offsets.h>
49 #include <asm/msr.h>
50 #include <asm/unistd.h>
51 #include <asm/thread_info.h>
52 #include <asm/hw_irq.h>
53 #include <asm/page_types.h>
54 #include <asm/irqflags.h>
55 #include <asm/paravirt.h>
56 #include <asm/ftrace.h>
57 #include <asm/percpu.h>
58 #include <linux/err.h>
60 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
61 #include <linux/elf-em.h>
62 #define AUDIT_ARCH_X86_64 (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
63 #define __AUDIT_ARCH_64BIT 0x80000000
64 #define __AUDIT_ARCH_LE 0x40000000
66 .code64
67 .section .entry.text, "ax"
69 #ifdef CONFIG_FUNCTION_TRACER
70 #ifdef CONFIG_DYNAMIC_FTRACE
71 ENTRY(mcount)
72 retq
73 END(mcount)
75 ENTRY(ftrace_caller)
76 cmpl $0, function_trace_stop
77 jne ftrace_stub
79 MCOUNT_SAVE_FRAME
81 movq 0x38(%rsp), %rdi
82 movq 8(%rbp), %rsi
83 subq $MCOUNT_INSN_SIZE, %rdi
85 GLOBAL(ftrace_call)
86 call ftrace_stub
88 MCOUNT_RESTORE_FRAME
90 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
91 GLOBAL(ftrace_graph_call)
92 jmp ftrace_stub
93 #endif
95 GLOBAL(ftrace_stub)
96 retq
97 END(ftrace_caller)
99 #else /* ! CONFIG_DYNAMIC_FTRACE */
100 ENTRY(mcount)
101 cmpl $0, function_trace_stop
102 jne ftrace_stub
104 cmpq $ftrace_stub, ftrace_trace_function
105 jnz trace
107 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
108 cmpq $ftrace_stub, ftrace_graph_return
109 jnz ftrace_graph_caller
111 cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
112 jnz ftrace_graph_caller
113 #endif
115 GLOBAL(ftrace_stub)
116 retq
118 trace:
119 MCOUNT_SAVE_FRAME
121 movq 0x38(%rsp), %rdi
122 movq 8(%rbp), %rsi
123 subq $MCOUNT_INSN_SIZE, %rdi
125 call *ftrace_trace_function
127 MCOUNT_RESTORE_FRAME
129 jmp ftrace_stub
130 END(mcount)
131 #endif /* CONFIG_DYNAMIC_FTRACE */
132 #endif /* CONFIG_FUNCTION_TRACER */
134 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
135 ENTRY(ftrace_graph_caller)
136 cmpl $0, function_trace_stop
137 jne ftrace_stub
139 MCOUNT_SAVE_FRAME
141 leaq 8(%rbp), %rdi
142 movq 0x38(%rsp), %rsi
143 movq (%rbp), %rdx
144 subq $MCOUNT_INSN_SIZE, %rsi
146 call prepare_ftrace_return
148 MCOUNT_RESTORE_FRAME
150 retq
151 END(ftrace_graph_caller)
153 GLOBAL(return_to_handler)
154 subq $24, %rsp
156 /* Save the return values */
157 movq %rax, (%rsp)
158 movq %rdx, 8(%rsp)
159 movq %rbp, %rdi
161 call ftrace_return_to_handler
163 movq %rax, %rdi
164 movq 8(%rsp), %rdx
165 movq (%rsp), %rax
166 addq $24, %rsp
167 jmp *%rdi
168 #endif
171 #ifndef CONFIG_PREEMPT
172 #define retint_kernel retint_restore_args
173 #endif
175 #ifdef CONFIG_PARAVIRT
176 ENTRY(native_usergs_sysret64)
177 swapgs
178 sysretq
179 ENDPROC(native_usergs_sysret64)
180 #endif /* CONFIG_PARAVIRT */
183 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
184 #ifdef CONFIG_TRACE_IRQFLAGS
185 bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */
186 jnc 1f
187 TRACE_IRQS_ON
188 1:
189 #endif
190 .endm
192 /*
193 * C code is not supposed to know about undefined top of stack. Every time
194 * a C function with an pt_regs argument is called from the SYSCALL based
195 * fast path FIXUP_TOP_OF_STACK is needed.
196 * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
197 * manipulation.
198 */
200 /* %rsp:at FRAMEEND */
201 .macro FIXUP_TOP_OF_STACK tmp offset=0
202 movq PER_CPU_VAR(old_rsp),\tmp
203 movq \tmp,RSP+\offset(%rsp)
204 movq $__USER_DS,SS+\offset(%rsp)
205 movq $__USER_CS,CS+\offset(%rsp)
206 movq $-1,RCX+\offset(%rsp)
207 movq R11+\offset(%rsp),\tmp /* get eflags */
208 movq \tmp,EFLAGS+\offset(%rsp)
209 .endm
211 .macro RESTORE_TOP_OF_STACK tmp offset=0
212 movq RSP+\offset(%rsp),\tmp
213 movq \tmp,PER_CPU_VAR(old_rsp)
214 movq EFLAGS+\offset(%rsp),\tmp
215 movq \tmp,R11+\offset(%rsp)
216 .endm
218 .macro FAKE_STACK_FRAME child_rip
219 /* push in order ss, rsp, eflags, cs, rip */
220 xorl %eax, %eax
221 pushq_cfi $__KERNEL_DS /* ss */
222 /*CFI_REL_OFFSET ss,0*/
223 pushq_cfi %rax /* rsp */
224 CFI_REL_OFFSET rsp,0
225 pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_BIT1) /* eflags - interrupts on */
226 /*CFI_REL_OFFSET rflags,0*/
227 pushq_cfi $__KERNEL_CS /* cs */
228 /*CFI_REL_OFFSET cs,0*/
229 pushq_cfi \child_rip /* rip */
230 CFI_REL_OFFSET rip,0
231 pushq_cfi %rax /* orig rax */
232 .endm
234 .macro UNFAKE_STACK_FRAME
235 addq $8*6, %rsp
236 CFI_ADJUST_CFA_OFFSET -(6*8)
237 .endm
239 /*
240 * initial frame state for interrupts (and exceptions without error code)
241 */
242 .macro EMPTY_FRAME start=1 offset=0
243 .if \start
244 CFI_STARTPROC simple
245 CFI_SIGNAL_FRAME
246 CFI_DEF_CFA rsp,8+\offset
247 .else
248 CFI_DEF_CFA_OFFSET 8+\offset
249 .endif
250 .endm
252 /*
253 * initial frame state for interrupts (and exceptions without error code)
254 */
255 .macro INTR_FRAME start=1 offset=0
256 EMPTY_FRAME \start, SS+8+\offset-RIP
257 /*CFI_REL_OFFSET ss, SS+\offset-RIP*/
258 CFI_REL_OFFSET rsp, RSP+\offset-RIP
259 /*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/
260 /*CFI_REL_OFFSET cs, CS+\offset-RIP*/
261 CFI_REL_OFFSET rip, RIP+\offset-RIP
262 .endm
264 /*
265 * initial frame state for exceptions with error code (and interrupts
266 * with vector already pushed)
267 */
268 .macro XCPT_FRAME start=1 offset=0
269 INTR_FRAME \start, RIP+\offset-ORIG_RAX
270 /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
271 .endm
273 /*
274 * frame that enables calling into C.
275 */
276 .macro PARTIAL_FRAME start=1 offset=0
277 XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET
278 CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET
279 CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET
280 CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET
281 CFI_REL_OFFSET rcx, RCX+\offset-ARGOFFSET
282 CFI_REL_OFFSET rax, RAX+\offset-ARGOFFSET
283 CFI_REL_OFFSET r8, R8+\offset-ARGOFFSET
284 CFI_REL_OFFSET r9, R9+\offset-ARGOFFSET
285 CFI_REL_OFFSET r10, R10+\offset-ARGOFFSET
286 CFI_REL_OFFSET r11, R11+\offset-ARGOFFSET
287 .endm
289 /*
290 * frame that enables passing a complete pt_regs to a C function.
291 */
292 .macro DEFAULT_FRAME start=1 offset=0
293 PARTIAL_FRAME \start, R11+\offset-R15
294 CFI_REL_OFFSET rbx, RBX+\offset
295 CFI_REL_OFFSET rbp, RBP+\offset
296 CFI_REL_OFFSET r12, R12+\offset
297 CFI_REL_OFFSET r13, R13+\offset
298 CFI_REL_OFFSET r14, R14+\offset
299 CFI_REL_OFFSET r15, R15+\offset
300 .endm
302 /* save partial stack frame */
303 .macro SAVE_ARGS_IRQ
304 cld
305 /* start from rbp in pt_regs and jump over */
306 movq_cfi rdi, RDI-RBP
307 movq_cfi rsi, RSI-RBP
308 movq_cfi rdx, RDX-RBP
309 movq_cfi rcx, RCX-RBP
310 movq_cfi rax, RAX-RBP
311 movq_cfi r8, R8-RBP
312 movq_cfi r9, R9-RBP
313 movq_cfi r10, R10-RBP
314 movq_cfi r11, R11-RBP
316 /* Save rbp so that we can unwind from get_irq_regs() */
317 movq_cfi rbp, 0
319 /* Save previous stack value */
320 movq %rsp, %rsi
322 leaq -RBP(%rsp),%rdi /* arg1 for handler */
323 testl $3, CS(%rdi)
324 je 1f
325 SWAPGS
326 /*
327 * irq_count is used to check if a CPU is already on an interrupt stack
328 * or not. While this is essentially redundant with preempt_count it is
329 * a little cheaper to use a separate counter in the PDA (short of
330 * moving irq_enter into assembly, which would be too much work)
331 */
332 1: incl PER_CPU_VAR(irq_count)
333 jne 2f
334 mov PER_CPU_VAR(irq_stack_ptr),%rsp
335 CFI_DEF_CFA_REGISTER rsi
337 2: /* Store previous stack value */
338 pushq %rsi
339 CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \
340 0x77 /* DW_OP_breg7 */, 0, \
341 0x06 /* DW_OP_deref */, \
342 0x08 /* DW_OP_const1u */, SS+8-RBP, \
343 0x22 /* DW_OP_plus */
344 /* We entered an interrupt context - irqs are off: */
345 TRACE_IRQS_OFF
346 .endm
348 ENTRY(save_rest)
349 PARTIAL_FRAME 1 REST_SKIP+8
350 movq 5*8+16(%rsp), %r11 /* save return address */
351 movq_cfi rbx, RBX+16
352 movq_cfi rbp, RBP+16
353 movq_cfi r12, R12+16
354 movq_cfi r13, R13+16
355 movq_cfi r14, R14+16
356 movq_cfi r15, R15+16
357 movq %r11, 8(%rsp) /* return address */
358 FIXUP_TOP_OF_STACK %r11, 16
359 ret
360 CFI_ENDPROC
361 END(save_rest)
363 /* save complete stack frame */
364 .pushsection .kprobes.text, "ax"
365 ENTRY(save_paranoid)
366 XCPT_FRAME 1 RDI+8
367 cld
368 movq_cfi rdi, RDI+8
369 movq_cfi rsi, RSI+8
370 movq_cfi rdx, RDX+8
371 movq_cfi rcx, RCX+8
372 movq_cfi rax, RAX+8
373 movq_cfi r8, R8+8
374 movq_cfi r9, R9+8
375 movq_cfi r10, R10+8
376 movq_cfi r11, R11+8
377 movq_cfi rbx, RBX+8
378 movq_cfi rbp, RBP+8
379 movq_cfi r12, R12+8
380 movq_cfi r13, R13+8
381 movq_cfi r14, R14+8
382 movq_cfi r15, R15+8
383 movl $1,%ebx
384 movl $MSR_GS_BASE,%ecx
385 rdmsr
386 testl %edx,%edx
387 js 1f /* negative -> in kernel */
388 SWAPGS
389 xorl %ebx,%ebx
390 1: ret
391 CFI_ENDPROC
392 END(save_paranoid)
393 .popsection
395 /*
396 * A newly forked process directly context switches into this address.
397 *
398 * rdi: prev task we switched from
399 */
400 ENTRY(ret_from_fork)
401 DEFAULT_FRAME
403 LOCK ; btr $TIF_FORK,TI_flags(%r8)
405 pushq_cfi kernel_eflags(%rip)
406 popfq_cfi # reset kernel eflags
408 call schedule_tail # rdi: 'prev' task parameter
410 GET_THREAD_INFO(%rcx)
412 RESTORE_REST
414 testl $3, CS-ARGOFFSET(%rsp) # from kernel_thread?
415 jz retint_restore_args
417 testl $_TIF_IA32, TI_flags(%rcx) # 32-bit compat task needs IRET
418 jnz int_ret_from_sys_call
420 RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
421 jmp ret_from_sys_call # go to the SYSRET fastpath
423 CFI_ENDPROC
424 END(ret_from_fork)
426 /*
427 * System call entry. Up to 6 arguments in registers are supported.
428 *
429 * SYSCALL does not save anything on the stack and does not change the
430 * stack pointer.
431 */
433 /*
434 * Register setup:
435 * rax system call number
436 * rdi arg0
437 * rcx return address for syscall/sysret, C arg3
438 * rsi arg1
439 * rdx arg2
440 * r10 arg3 (--> moved to rcx for C)
441 * r8 arg4
442 * r9 arg5
443 * r11 eflags for syscall/sysret, temporary for C
444 * r12-r15,rbp,rbx saved by C code, not touched.
445 *
446 * Interrupts are off on entry.
447 * Only called from user space.
448 *
449 * XXX if we had a free scratch register we could save the RSP into the stack frame
450 * and report it properly in ps. Unfortunately we haven't.
451 *
452 * When user can change the frames always force IRET. That is because
453 * it deals with uncanonical addresses better. SYSRET has trouble
454 * with them due to bugs in both AMD and Intel CPUs.
455 */
457 ENTRY(system_call)
458 CFI_STARTPROC simple
459 CFI_SIGNAL_FRAME
460 CFI_DEF_CFA rsp,KERNEL_STACK_OFFSET
461 CFI_REGISTER rip,rcx
462 /*CFI_REGISTER rflags,r11*/
463 SWAPGS_UNSAFE_STACK
464 /*
465 * A hypervisor implementation might want to use a label
466 * after the swapgs, so that it can do the swapgs
467 * for the guest and jump here on syscall.
468 */
469 GLOBAL(system_call_after_swapgs)
471 movq %rsp,PER_CPU_VAR(old_rsp)
472 movq PER_CPU_VAR(kernel_stack),%rsp
473 /*
474 * No need to follow this irqs off/on section - it's straight
475 * and short:
476 */
477 ENABLE_INTERRUPTS(CLBR_NONE)
478 SAVE_ARGS 8,0
479 movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
480 movq %rcx,RIP-ARGOFFSET(%rsp)
481 CFI_REL_OFFSET rip,RIP-ARGOFFSET
482 testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
483 jnz tracesys
484 system_call_fastpath:
485 cmpq $__NR_syscall_max,%rax
486 ja badsys
487 movq %r10,%rcx
488 call *sys_call_table(,%rax,8) # XXX: rip relative
489 movq %rax,RAX-ARGOFFSET(%rsp)
490 /*
491 * Syscall return path ending with SYSRET (fast path)
492 * Has incomplete stack frame and undefined top of stack.
493 */
494 ret_from_sys_call:
495 movl $_TIF_ALLWORK_MASK,%edi
496 /* edi: flagmask */
497 sysret_check:
498 LOCKDEP_SYS_EXIT
499 DISABLE_INTERRUPTS(CLBR_NONE)
500 TRACE_IRQS_OFF
501 movl TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET),%edx
502 andl %edi,%edx
503 jnz sysret_careful
504 CFI_REMEMBER_STATE
505 /*
506 * sysretq will re-enable interrupts:
507 */
508 TRACE_IRQS_ON
509 movq RIP-ARGOFFSET(%rsp),%rcx
510 CFI_REGISTER rip,rcx
511 RESTORE_ARGS 1,-ARG_SKIP,0
512 /*CFI_REGISTER rflags,r11*/
513 movq PER_CPU_VAR(old_rsp), %rsp
514 USERGS_SYSRET64
516 CFI_RESTORE_STATE
517 /* Handle reschedules */
518 /* edx: work, edi: workmask */
519 sysret_careful:
520 bt $TIF_NEED_RESCHED,%edx
521 jnc sysret_signal
522 TRACE_IRQS_ON
523 ENABLE_INTERRUPTS(CLBR_NONE)
524 pushq_cfi %rdi
525 call schedule
526 popq_cfi %rdi
527 jmp sysret_check
529 /* Handle a signal */
530 sysret_signal:
531 TRACE_IRQS_ON
532 ENABLE_INTERRUPTS(CLBR_NONE)
533 #ifdef CONFIG_AUDITSYSCALL
534 bt $TIF_SYSCALL_AUDIT,%edx
535 jc sysret_audit
536 #endif
537 /*
538 * We have a signal, or exit tracing or single-step.
539 * These all wind up with the iret return path anyway,
540 * so just join that path right now.
541 */
542 FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
543 jmp int_check_syscall_exit_work
545 badsys:
546 movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
547 jmp ret_from_sys_call
549 #ifdef CONFIG_AUDITSYSCALL
550 /*
551 * Fast path for syscall audit without full syscall trace.
552 * We just call __audit_syscall_entry() directly, and then
553 * jump back to the normal fast path.
554 */
555 auditsys:
556 movq %r10,%r9 /* 6th arg: 4th syscall arg */
557 movq %rdx,%r8 /* 5th arg: 3rd syscall arg */
558 movq %rsi,%rcx /* 4th arg: 2nd syscall arg */
559 movq %rdi,%rdx /* 3rd arg: 1st syscall arg */
560 movq %rax,%rsi /* 2nd arg: syscall number */
561 movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */
562 call __audit_syscall_entry
563 LOAD_ARGS 0 /* reload call-clobbered registers */
564 jmp system_call_fastpath
566 /*
567 * Return fast path for syscall audit. Call __audit_syscall_exit()
568 * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
569 * masked off.
570 */
571 sysret_audit:
572 movq RAX-ARGOFFSET(%rsp),%rsi /* second arg, syscall return value */
573 cmpq $-MAX_ERRNO,%rsi /* is it < -MAX_ERRNO? */
574 setbe %al /* 1 if so, 0 if not */
575 movzbl %al,%edi /* zero-extend that into %edi */
576 call __audit_syscall_exit
577 movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
578 jmp sysret_check
579 #endif /* CONFIG_AUDITSYSCALL */
581 /* Do syscall tracing */
582 tracesys:
583 #ifdef CONFIG_AUDITSYSCALL
584 testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
585 jz auditsys
586 #endif
587 SAVE_REST
588 movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
589 FIXUP_TOP_OF_STACK %rdi
590 movq %rsp,%rdi
591 call syscall_trace_enter
592 /*
593 * Reload arg registers from stack in case ptrace changed them.
594 * We don't reload %rax because syscall_trace_enter() returned
595 * the value it wants us to use in the table lookup.
596 */
597 LOAD_ARGS ARGOFFSET, 1
598 RESTORE_REST
599 cmpq $__NR_syscall_max,%rax
600 ja int_ret_from_sys_call /* RAX(%rsp) set to -ENOSYS above */
601 movq %r10,%rcx /* fixup for C */
602 call *sys_call_table(,%rax,8)
603 movq %rax,RAX-ARGOFFSET(%rsp)
604 /* Use IRET because user could have changed frame */
606 /*
607 * Syscall return path ending with IRET.
608 * Has correct top of stack, but partial stack frame.
609 */
610 GLOBAL(int_ret_from_sys_call)
611 DISABLE_INTERRUPTS(CLBR_NONE)
612 TRACE_IRQS_OFF
613 movl $_TIF_ALLWORK_MASK,%edi
614 /* edi: mask to check */
615 GLOBAL(int_with_check)
616 LOCKDEP_SYS_EXIT_IRQ
617 GET_THREAD_INFO(%rcx)
618 movl TI_flags(%rcx),%edx
619 andl %edi,%edx
620 jnz int_careful
621 andl $~TS_COMPAT,TI_status(%rcx)
622 jmp retint_swapgs
624 /* Either reschedule or signal or syscall exit tracking needed. */
625 /* First do a reschedule test. */
626 /* edx: work, edi: workmask */
627 int_careful:
628 bt $TIF_NEED_RESCHED,%edx
629 jnc int_very_careful
630 TRACE_IRQS_ON
631 ENABLE_INTERRUPTS(CLBR_NONE)
632 pushq_cfi %rdi
633 call schedule
634 popq_cfi %rdi
635 DISABLE_INTERRUPTS(CLBR_NONE)
636 TRACE_IRQS_OFF
637 jmp int_with_check
639 /* handle signals and tracing -- both require a full stack frame */
640 int_very_careful:
641 TRACE_IRQS_ON
642 ENABLE_INTERRUPTS(CLBR_NONE)
643 int_check_syscall_exit_work:
644 SAVE_REST
645 /* Check for syscall exit trace */
646 testl $_TIF_WORK_SYSCALL_EXIT,%edx
647 jz int_signal
648 pushq_cfi %rdi
649 leaq 8(%rsp),%rdi # &ptregs -> arg1
650 call syscall_trace_leave
651 popq_cfi %rdi
652 andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
653 jmp int_restore_rest
655 int_signal:
656 testl $_TIF_DO_NOTIFY_MASK,%edx
657 jz 1f
658 movq %rsp,%rdi # &ptregs -> arg1
659 xorl %esi,%esi # oldset -> arg2
660 call do_notify_resume
661 1: movl $_TIF_WORK_MASK,%edi
662 int_restore_rest:
663 RESTORE_REST
664 DISABLE_INTERRUPTS(CLBR_NONE)
665 TRACE_IRQS_OFF
666 jmp int_with_check
667 CFI_ENDPROC
668 END(system_call)
670 /*
671 * Certain special system calls that need to save a complete full stack frame.
672 */
673 .macro PTREGSCALL label,func,arg
674 ENTRY(\label)
675 PARTIAL_FRAME 1 8 /* offset 8: return address */
676 subq $REST_SKIP, %rsp
677 CFI_ADJUST_CFA_OFFSET REST_SKIP
678 call save_rest
679 DEFAULT_FRAME 0 8 /* offset 8: return address */
680 leaq 8(%rsp), \arg /* pt_regs pointer */
681 call \func
682 jmp ptregscall_common
683 CFI_ENDPROC
684 END(\label)
685 .endm
687 PTREGSCALL stub_clone, sys_clone, %r8
688 PTREGSCALL stub_fork, sys_fork, %rdi
689 PTREGSCALL stub_vfork, sys_vfork, %rdi
690 PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
691 PTREGSCALL stub_iopl, sys_iopl, %rsi
693 ENTRY(ptregscall_common)
694 DEFAULT_FRAME 1 8 /* offset 8: return address */
695 RESTORE_TOP_OF_STACK %r11, 8
696 movq_cfi_restore R15+8, r15
697 movq_cfi_restore R14+8, r14
698 movq_cfi_restore R13+8, r13
699 movq_cfi_restore R12+8, r12
700 movq_cfi_restore RBP+8, rbp
701 movq_cfi_restore RBX+8, rbx
702 ret $REST_SKIP /* pop extended registers */
703 CFI_ENDPROC
704 END(ptregscall_common)
706 ENTRY(stub_execve)
707 CFI_STARTPROC
708 addq $8, %rsp
709 PARTIAL_FRAME 0
710 SAVE_REST
711 FIXUP_TOP_OF_STACK %r11
712 movq %rsp, %rcx
713 call sys_execve
714 RESTORE_TOP_OF_STACK %r11
715 movq %rax,RAX(%rsp)
716 RESTORE_REST
717 jmp int_ret_from_sys_call
718 CFI_ENDPROC
719 END(stub_execve)
721 /*
722 * sigreturn is special because it needs to restore all registers on return.
723 * This cannot be done with SYSRET, so use the IRET return path instead.
724 */
725 ENTRY(stub_rt_sigreturn)
726 CFI_STARTPROC
727 addq $8, %rsp
728 PARTIAL_FRAME 0
729 SAVE_REST
730 movq %rsp,%rdi
731 FIXUP_TOP_OF_STACK %r11
732 call sys_rt_sigreturn
733 movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
734 RESTORE_REST
735 jmp int_ret_from_sys_call
736 CFI_ENDPROC
737 END(stub_rt_sigreturn)
739 /*
740 * Build the entry stubs and pointer table with some assembler magic.
741 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
742 * single cache line on all modern x86 implementations.
743 */
744 .section .init.rodata,"a"
745 ENTRY(interrupt)
746 .section .entry.text
747 .p2align 5
748 .p2align CONFIG_X86_L1_CACHE_SHIFT
749 ENTRY(irq_entries_start)
750 INTR_FRAME
751 vector=FIRST_EXTERNAL_VECTOR
752 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
753 .balign 32
754 .rept 7
755 .if vector < NR_VECTORS
756 .if vector <> FIRST_EXTERNAL_VECTOR
757 CFI_ADJUST_CFA_OFFSET -8
758 .endif
759 1: pushq_cfi $(~vector+0x80) /* Note: always in signed byte range */
760 .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
761 jmp 2f
762 .endif
763 .previous
764 .quad 1b
765 .section .entry.text
766 vector=vector+1
767 .endif
768 .endr
769 2: jmp common_interrupt
770 .endr
771 CFI_ENDPROC
772 END(irq_entries_start)
774 .previous
775 END(interrupt)
776 .previous
778 /*
779 * Interrupt entry/exit.
780 *
781 * Interrupt entry points save only callee clobbered registers in fast path.
782 *
783 * Entry runs with interrupts off.
784 */
786 /* 0(%rsp): ~(interrupt number) */
787 .macro interrupt func
788 /* reserve pt_regs for scratch regs and rbp */
789 subq $ORIG_RAX-RBP, %rsp
790 CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP
791 SAVE_ARGS_IRQ
792 call \func
793 .endm
795 /*
796 * Interrupt entry/exit should be protected against kprobes
797 */
798 .pushsection .kprobes.text, "ax"
799 /*
800 * The interrupt stubs push (~vector+0x80) onto the stack and
801 * then jump to common_interrupt.
802 */
803 .p2align CONFIG_X86_L1_CACHE_SHIFT
804 common_interrupt:
805 XCPT_FRAME
806 addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
807 interrupt do_IRQ
808 /* 0(%rsp): old_rsp-ARGOFFSET */
809 ret_from_intr:
810 DISABLE_INTERRUPTS(CLBR_NONE)
811 TRACE_IRQS_OFF
812 decl PER_CPU_VAR(irq_count)
814 /* Restore saved previous stack */
815 popq %rsi
816 CFI_DEF_CFA_REGISTER rsi
817 leaq ARGOFFSET-RBP(%rsi), %rsp
818 CFI_DEF_CFA_REGISTER rsp
819 CFI_ADJUST_CFA_OFFSET RBP-ARGOFFSET
821 exit_intr:
822 GET_THREAD_INFO(%rcx)
823 testl $3,CS-ARGOFFSET(%rsp)
824 je retint_kernel
826 /* Interrupt came from user space */
827 /*
828 * Has a correct top of stack, but a partial stack frame
829 * %rcx: thread info. Interrupts off.
830 */
831 retint_with_reschedule:
832 movl $_TIF_WORK_MASK,%edi
833 retint_check:
834 LOCKDEP_SYS_EXIT_IRQ
835 movl TI_flags(%rcx),%edx
836 andl %edi,%edx
837 CFI_REMEMBER_STATE
838 jnz retint_careful
840 retint_swapgs: /* return to user-space */
841 /*
842 * The iretq could re-enable interrupts:
843 */
844 DISABLE_INTERRUPTS(CLBR_ANY)
845 TRACE_IRQS_IRETQ
846 SWAPGS
847 jmp restore_args
849 retint_restore_args: /* return to kernel space */
850 DISABLE_INTERRUPTS(CLBR_ANY)
851 /*
852 * The iretq could re-enable interrupts:
853 */
854 TRACE_IRQS_IRETQ
855 restore_args:
856 RESTORE_ARGS 1,8,1
858 irq_return:
859 INTERRUPT_RETURN
861 .section __ex_table, "a"
862 .quad irq_return, bad_iret
863 .previous
865 #ifdef CONFIG_PARAVIRT
866 ENTRY(native_iret)
867 iretq
869 .section __ex_table,"a"
870 .quad native_iret, bad_iret
871 .previous
872 #endif
874 .section .fixup,"ax"
875 bad_iret:
876 /*
877 * The iret traps when the %cs or %ss being restored is bogus.
878 * We've lost the original trap vector and error code.
879 * #GPF is the most likely one to get for an invalid selector.
880 * So pretend we completed the iret and took the #GPF in user mode.
881 *
882 * We are now running with the kernel GS after exception recovery.
883 * But error_entry expects us to have user GS to match the user %cs,
884 * so swap back.
885 */
886 pushq $0
888 SWAPGS
889 jmp general_protection
891 .previous
893 /* edi: workmask, edx: work */
894 retint_careful:
895 CFI_RESTORE_STATE
896 bt $TIF_NEED_RESCHED,%edx
897 jnc retint_signal
898 TRACE_IRQS_ON
899 ENABLE_INTERRUPTS(CLBR_NONE)
900 pushq_cfi %rdi
901 call schedule
902 popq_cfi %rdi
903 GET_THREAD_INFO(%rcx)
904 DISABLE_INTERRUPTS(CLBR_NONE)
905 TRACE_IRQS_OFF
906 jmp retint_check
908 retint_signal:
909 testl $_TIF_DO_NOTIFY_MASK,%edx
910 jz retint_swapgs
911 TRACE_IRQS_ON
912 ENABLE_INTERRUPTS(CLBR_NONE)
913 SAVE_REST
914 movq $-1,ORIG_RAX(%rsp)
915 xorl %esi,%esi # oldset
916 movq %rsp,%rdi # &pt_regs
917 call do_notify_resume
918 RESTORE_REST
919 DISABLE_INTERRUPTS(CLBR_NONE)
920 TRACE_IRQS_OFF
921 GET_THREAD_INFO(%rcx)
922 jmp retint_with_reschedule
924 #ifdef CONFIG_PREEMPT
925 /* Returning to kernel space. Check if we need preemption */
926 /* rcx: threadinfo. interrupts off. */
927 ENTRY(retint_kernel)
928 cmpl $0,TI_preempt_count(%rcx)
929 jnz retint_restore_args
930 bt $TIF_NEED_RESCHED,TI_flags(%rcx)
931 jnc retint_restore_args
932 bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */
933 jnc retint_restore_args
934 call preempt_schedule_irq
935 jmp exit_intr
936 #endif
938 CFI_ENDPROC
939 END(common_interrupt)
940 /*
941 * End of kprobes section
942 */
943 .popsection
945 /*
946 * APIC interrupts.
947 */
948 .macro apicinterrupt num sym do_sym
949 ENTRY(\sym)
950 INTR_FRAME
951 pushq_cfi $~(\num)
952 .Lcommon_\sym:
953 interrupt \do_sym
954 jmp ret_from_intr
955 CFI_ENDPROC
956 END(\sym)
957 .endm
959 #ifdef CONFIG_SMP
960 apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \
961 irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt
962 apicinterrupt REBOOT_VECTOR \
963 reboot_interrupt smp_reboot_interrupt
964 #endif
966 #ifdef CONFIG_X86_UV
967 apicinterrupt UV_BAU_MESSAGE \
968 uv_bau_message_intr1 uv_bau_message_interrupt
969 #endif
970 apicinterrupt LOCAL_TIMER_VECTOR \
971 apic_timer_interrupt smp_apic_timer_interrupt
972 apicinterrupt X86_PLATFORM_IPI_VECTOR \
973 x86_platform_ipi smp_x86_platform_ipi
975 #ifdef CONFIG_SMP
976 ALIGN
977 INTR_FRAME
978 .irp idx,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \
979 16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
980 .if NUM_INVALIDATE_TLB_VECTORS > \idx
981 ENTRY(invalidate_interrupt\idx)
982 pushq_cfi $~(INVALIDATE_TLB_VECTOR_START+\idx)
983 jmp .Lcommon_invalidate_interrupt0
984 CFI_ADJUST_CFA_OFFSET -8
985 END(invalidate_interrupt\idx)
986 .endif
987 .endr
988 CFI_ENDPROC
989 apicinterrupt INVALIDATE_TLB_VECTOR_START, \
990 invalidate_interrupt0, smp_invalidate_interrupt
991 #endif
993 apicinterrupt THRESHOLD_APIC_VECTOR \
994 threshold_interrupt smp_threshold_interrupt
995 apicinterrupt THERMAL_APIC_VECTOR \
996 thermal_interrupt smp_thermal_interrupt
998 #ifdef CONFIG_SMP
999 apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \
1000 call_function_single_interrupt smp_call_function_single_interrupt
1001 apicinterrupt CALL_FUNCTION_VECTOR \
1002 call_function_interrupt smp_call_function_interrupt
1003 apicinterrupt RESCHEDULE_VECTOR \
1004 reschedule_interrupt smp_reschedule_interrupt
1005 #endif
1007 apicinterrupt ERROR_APIC_VECTOR \
1008 error_interrupt smp_error_interrupt
1009 apicinterrupt SPURIOUS_APIC_VECTOR \
1010 spurious_interrupt smp_spurious_interrupt
1012 #ifdef CONFIG_IRQ_WORK
1013 apicinterrupt IRQ_WORK_VECTOR \
1014 irq_work_interrupt smp_irq_work_interrupt
1015 #endif
1017 /*
1018 * Exception entry points.
1019 */
1020 .macro zeroentry sym do_sym
1021 ENTRY(\sym)
1022 INTR_FRAME
1023 PARAVIRT_ADJUST_EXCEPTION_FRAME
1024 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1025 subq $ORIG_RAX-R15, %rsp
1026 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1027 call error_entry
1028 DEFAULT_FRAME 0
1029 movq %rsp,%rdi /* pt_regs pointer */
1030 xorl %esi,%esi /* no error code */
1031 call \do_sym
1032 jmp error_exit /* %ebx: no swapgs flag */
1033 CFI_ENDPROC
1034 END(\sym)
1035 .endm
1037 .macro paranoidzeroentry sym do_sym
1038 ENTRY(\sym)
1039 INTR_FRAME
1040 PARAVIRT_ADJUST_EXCEPTION_FRAME
1041 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1042 subq $ORIG_RAX-R15, %rsp
1043 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1044 call save_paranoid
1045 TRACE_IRQS_OFF
1046 movq %rsp,%rdi /* pt_regs pointer */
1047 xorl %esi,%esi /* no error code */
1048 call \do_sym
1049 jmp paranoid_exit /* %ebx: no swapgs flag */
1050 CFI_ENDPROC
1051 END(\sym)
1052 .endm
1054 #define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
1055 .macro paranoidzeroentry_ist sym do_sym ist
1056 ENTRY(\sym)
1057 INTR_FRAME
1058 PARAVIRT_ADJUST_EXCEPTION_FRAME
1059 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1060 subq $ORIG_RAX-R15, %rsp
1061 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1062 call save_paranoid
1063 TRACE_IRQS_OFF
1064 movq %rsp,%rdi /* pt_regs pointer */
1065 xorl %esi,%esi /* no error code */
1066 subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1067 call \do_sym
1068 addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1069 jmp paranoid_exit /* %ebx: no swapgs flag */
1070 CFI_ENDPROC
1071 END(\sym)
1072 .endm
1074 .macro errorentry sym do_sym
1075 ENTRY(\sym)
1076 XCPT_FRAME
1077 PARAVIRT_ADJUST_EXCEPTION_FRAME
1078 subq $ORIG_RAX-R15, %rsp
1079 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1080 call error_entry
1081 DEFAULT_FRAME 0
1082 movq %rsp,%rdi /* pt_regs pointer */
1083 movq ORIG_RAX(%rsp),%rsi /* get error code */
1084 movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
1085 call \do_sym
1086 jmp error_exit /* %ebx: no swapgs flag */
1087 CFI_ENDPROC
1088 END(\sym)
1089 .endm
1091 /* error code is on the stack already */
1092 .macro paranoiderrorentry sym do_sym
1093 ENTRY(\sym)
1094 XCPT_FRAME
1095 PARAVIRT_ADJUST_EXCEPTION_FRAME
1096 subq $ORIG_RAX-R15, %rsp
1097 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1098 call save_paranoid
1099 DEFAULT_FRAME 0
1100 TRACE_IRQS_OFF
1101 movq %rsp,%rdi /* pt_regs pointer */
1102 movq ORIG_RAX(%rsp),%rsi /* get error code */
1103 movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
1104 call \do_sym
1105 jmp paranoid_exit /* %ebx: no swapgs flag */
1106 CFI_ENDPROC
1107 END(\sym)
1108 .endm
1110 zeroentry divide_error do_divide_error
1111 zeroentry overflow do_overflow
1112 zeroentry bounds do_bounds
1113 zeroentry invalid_op do_invalid_op
1114 zeroentry device_not_available do_device_not_available
1115 paranoiderrorentry double_fault do_double_fault
1116 zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun
1117 errorentry invalid_TSS do_invalid_TSS
1118 errorentry segment_not_present do_segment_not_present
1119 zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
1120 zeroentry coprocessor_error do_coprocessor_error
1121 errorentry alignment_check do_alignment_check
1122 zeroentry simd_coprocessor_error do_simd_coprocessor_error
1125 /* Reload gs selector with exception handling */
1126 /* edi: new selector */
1127 ENTRY(native_load_gs_index)
1128 CFI_STARTPROC
1129 pushfq_cfi
1130 DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
1131 SWAPGS
1132 gs_change:
1133 movl %edi,%gs
1134 2: mfence /* workaround */
1135 SWAPGS
1136 popfq_cfi
1137 ret
1138 CFI_ENDPROC
1139 END(native_load_gs_index)
1141 .section __ex_table,"a"
1142 .align 8
1143 .quad gs_change,bad_gs
1144 .previous
1145 .section .fixup,"ax"
1146 /* running with kernelgs */
1147 bad_gs:
1148 SWAPGS /* switch back to user gs */
1149 xorl %eax,%eax
1150 movl %eax,%gs
1151 jmp 2b
1152 .previous
1154 ENTRY(kernel_thread_helper)
1155 pushq $0 # fake return address
1156 CFI_STARTPROC
1157 /*
1158 * Here we are in the child and the registers are set as they were
1159 * at kernel_thread() invocation in the parent.
1160 */
1161 call *%rsi
1162 # exit
1163 mov %eax, %edi
1164 call do_exit
1165 ud2 # padding for call trace
1166 CFI_ENDPROC
1167 END(kernel_thread_helper)
1169 /*
1170 * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
1171 *
1172 * C extern interface:
1173 * extern long execve(const char *name, char **argv, char **envp)
1174 *
1175 * asm input arguments:
1176 * rdi: name, rsi: argv, rdx: envp
1177 *
1178 * We want to fallback into:
1179 * extern long sys_execve(const char *name, char **argv,char **envp, struct pt_regs *regs)
1180 *
1181 * do_sys_execve asm fallback arguments:
1182 * rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
1183 */
1184 ENTRY(kernel_execve)
1185 CFI_STARTPROC
1186 FAKE_STACK_FRAME $0
1187 SAVE_ALL
1188 movq %rsp,%rcx
1189 call sys_execve
1190 movq %rax, RAX(%rsp)
1191 RESTORE_REST
1192 testq %rax,%rax
1193 je int_ret_from_sys_call
1194 RESTORE_ARGS
1195 UNFAKE_STACK_FRAME
1196 ret
1197 CFI_ENDPROC
1198 END(kernel_execve)
1200 /* Call softirq on interrupt stack. Interrupts are off. */
1201 ENTRY(call_softirq)
1202 CFI_STARTPROC
1203 pushq_cfi %rbp
1204 CFI_REL_OFFSET rbp,0
1205 mov %rsp,%rbp
1206 CFI_DEF_CFA_REGISTER rbp
1207 incl PER_CPU_VAR(irq_count)
1208 cmove PER_CPU_VAR(irq_stack_ptr),%rsp
1209 push %rbp # backlink for old unwinder
1210 call __do_softirq
1211 leaveq
1212 CFI_RESTORE rbp
1213 CFI_DEF_CFA_REGISTER rsp
1214 CFI_ADJUST_CFA_OFFSET -8
1215 decl PER_CPU_VAR(irq_count)
1216 ret
1217 CFI_ENDPROC
1218 END(call_softirq)
1220 #ifdef CONFIG_XEN
1221 zeroentry xen_hypervisor_callback xen_do_hypervisor_callback
1223 /*
1224 * A note on the "critical region" in our callback handler.
1225 * We want to avoid stacking callback handlers due to events occurring
1226 * during handling of the last event. To do this, we keep events disabled
1227 * until we've done all processing. HOWEVER, we must enable events before
1228 * popping the stack frame (can't be done atomically) and so it would still
1229 * be possible to get enough handler activations to overflow the stack.
1230 * Although unlikely, bugs of that kind are hard to track down, so we'd
1231 * like to avoid the possibility.
1232 * So, on entry to the handler we detect whether we interrupted an
1233 * existing activation in its critical region -- if so, we pop the current
1234 * activation and restart the handler using the previous one.
1235 */
1236 ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
1237 CFI_STARTPROC
1238 /*
1239 * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
1240 * see the correct pointer to the pt_regs
1241 */
1242 movq %rdi, %rsp # we don't return, adjust the stack frame
1243 CFI_ENDPROC
1244 DEFAULT_FRAME
1245 11: incl PER_CPU_VAR(irq_count)
1246 movq %rsp,%rbp
1247 CFI_DEF_CFA_REGISTER rbp
1248 cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
1249 pushq %rbp # backlink for old unwinder
1250 call xen_evtchn_do_upcall
1251 popq %rsp
1252 CFI_DEF_CFA_REGISTER rsp
1253 decl PER_CPU_VAR(irq_count)
1254 jmp error_exit
1255 CFI_ENDPROC
1256 END(xen_do_hypervisor_callback)
1258 /*
1259 * Hypervisor uses this for application faults while it executes.
1260 * We get here for two reasons:
1261 * 1. Fault while reloading DS, ES, FS or GS
1262 * 2. Fault while executing IRET
1263 * Category 1 we do not need to fix up as Xen has already reloaded all segment
1264 * registers that could be reloaded and zeroed the others.
1265 * Category 2 we fix up by killing the current process. We cannot use the
1266 * normal Linux return path in this case because if we use the IRET hypercall
1267 * to pop the stack frame we end up in an infinite loop of failsafe callbacks.
1268 * We distinguish between categories by comparing each saved segment register
1269 * with its current contents: any discrepancy means we in category 1.
1270 */
1271 ENTRY(xen_failsafe_callback)
1272 INTR_FRAME 1 (6*8)
1273 /*CFI_REL_OFFSET gs,GS*/
1274 /*CFI_REL_OFFSET fs,FS*/
1275 /*CFI_REL_OFFSET es,ES*/
1276 /*CFI_REL_OFFSET ds,DS*/
1277 CFI_REL_OFFSET r11,8
1278 CFI_REL_OFFSET rcx,0
1279 movw %ds,%cx
1280 cmpw %cx,0x10(%rsp)
1281 CFI_REMEMBER_STATE
1282 jne 1f
1283 movw %es,%cx
1284 cmpw %cx,0x18(%rsp)
1285 jne 1f
1286 movw %fs,%cx
1287 cmpw %cx,0x20(%rsp)
1288 jne 1f
1289 movw %gs,%cx
1290 cmpw %cx,0x28(%rsp)
1291 jne 1f
1292 /* All segments match their saved values => Category 2 (Bad IRET). */
1293 movq (%rsp),%rcx
1294 CFI_RESTORE rcx
1295 movq 8(%rsp),%r11
1296 CFI_RESTORE r11
1297 addq $0x30,%rsp
1298 CFI_ADJUST_CFA_OFFSET -0x30
1299 pushq_cfi $0 /* RIP */
1300 pushq_cfi %r11
1301 pushq_cfi %rcx
1302 jmp general_protection
1303 CFI_RESTORE_STATE
1304 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
1305 movq (%rsp),%rcx
1306 CFI_RESTORE rcx
1307 movq 8(%rsp),%r11
1308 CFI_RESTORE r11
1309 addq $0x30,%rsp
1310 CFI_ADJUST_CFA_OFFSET -0x30
1311 pushq_cfi $0
1312 SAVE_ALL
1313 jmp error_exit
1314 CFI_ENDPROC
1315 END(xen_failsafe_callback)
1317 apicinterrupt XEN_HVM_EVTCHN_CALLBACK \
1318 xen_hvm_callback_vector xen_evtchn_do_upcall
1320 #endif /* CONFIG_XEN */
1322 /*
1323 * Some functions should be protected against kprobes
1324 */
1325 .pushsection .kprobes.text, "ax"
1327 paranoidzeroentry_ist debug do_debug DEBUG_STACK
1328 paranoidzeroentry_ist int3 do_int3 DEBUG_STACK
1329 paranoiderrorentry stack_segment do_stack_segment
1330 #ifdef CONFIG_XEN
1331 zeroentry xen_debug do_debug
1332 zeroentry xen_int3 do_int3
1333 errorentry xen_stack_segment do_stack_segment
1334 #endif
1335 errorentry general_protection do_general_protection
1336 errorentry page_fault do_page_fault
1337 #ifdef CONFIG_KVM_GUEST
1338 errorentry async_page_fault do_async_page_fault
1339 #endif
1340 #ifdef CONFIG_X86_MCE
1341 paranoidzeroentry machine_check *machine_check_vector(%rip)
1342 #endif
1344 /*
1345 * "Paranoid" exit path from exception stack.
1346 * Paranoid because this is used by NMIs and cannot take
1347 * any kernel state for granted.
1348 * We don't do kernel preemption checks here, because only
1349 * NMI should be common and it does not enable IRQs and
1350 * cannot get reschedule ticks.
1351 *
1352 * "trace" is 0 for the NMI handler only, because irq-tracing
1353 * is fundamentally NMI-unsafe. (we cannot change the soft and
1354 * hard flags at once, atomically)
1355 */
1357 /* ebx: no swapgs flag */
1358 ENTRY(paranoid_exit)
1359 DEFAULT_FRAME
1360 DISABLE_INTERRUPTS(CLBR_NONE)
1361 TRACE_IRQS_OFF
1362 testl %ebx,%ebx /* swapgs needed? */
1363 jnz paranoid_restore
1364 testl $3,CS(%rsp)
1365 jnz paranoid_userspace
1366 paranoid_swapgs:
1367 TRACE_IRQS_IRETQ 0
1368 SWAPGS_UNSAFE_STACK
1369 RESTORE_ALL 8
1370 jmp irq_return
1371 paranoid_restore:
1372 TRACE_IRQS_IRETQ 0
1373 RESTORE_ALL 8
1374 jmp irq_return
1375 paranoid_userspace:
1376 GET_THREAD_INFO(%rcx)
1377 movl TI_flags(%rcx),%ebx
1378 andl $_TIF_WORK_MASK,%ebx
1379 jz paranoid_swapgs
1380 movq %rsp,%rdi /* &pt_regs */
1381 call sync_regs
1382 movq %rax,%rsp /* switch stack for scheduling */
1383 testl $_TIF_NEED_RESCHED,%ebx
1384 jnz paranoid_schedule
1385 movl %ebx,%edx /* arg3: thread flags */
1386 TRACE_IRQS_ON
1387 ENABLE_INTERRUPTS(CLBR_NONE)
1388 xorl %esi,%esi /* arg2: oldset */
1389 movq %rsp,%rdi /* arg1: &pt_regs */
1390 call do_notify_resume
1391 DISABLE_INTERRUPTS(CLBR_NONE)
1392 TRACE_IRQS_OFF
1393 jmp paranoid_userspace
1394 paranoid_schedule:
1395 TRACE_IRQS_ON
1396 ENABLE_INTERRUPTS(CLBR_ANY)
1397 call schedule
1398 DISABLE_INTERRUPTS(CLBR_ANY)
1399 TRACE_IRQS_OFF
1400 jmp paranoid_userspace
1401 CFI_ENDPROC
1402 END(paranoid_exit)
1404 /*
1405 * Exception entry point. This expects an error code/orig_rax on the stack.
1406 * returns in "no swapgs flag" in %ebx.
1407 */
1408 ENTRY(error_entry)
1409 XCPT_FRAME
1410 CFI_ADJUST_CFA_OFFSET 15*8
1411 /* oldrax contains error code */
1412 cld
1413 movq_cfi rdi, RDI+8
1414 movq_cfi rsi, RSI+8
1415 movq_cfi rdx, RDX+8
1416 movq_cfi rcx, RCX+8
1417 movq_cfi rax, RAX+8
1418 movq_cfi r8, R8+8
1419 movq_cfi r9, R9+8
1420 movq_cfi r10, R10+8
1421 movq_cfi r11, R11+8
1422 movq_cfi rbx, RBX+8
1423 movq_cfi rbp, RBP+8
1424 movq_cfi r12, R12+8
1425 movq_cfi r13, R13+8
1426 movq_cfi r14, R14+8
1427 movq_cfi r15, R15+8
1428 xorl %ebx,%ebx
1429 testl $3,CS+8(%rsp)
1430 je error_kernelspace
1431 error_swapgs:
1432 SWAPGS
1433 error_sti:
1434 TRACE_IRQS_OFF
1435 ret
1437 /*
1438 * There are two places in the kernel that can potentially fault with
1439 * usergs. Handle them here. The exception handlers after iret run with
1440 * kernel gs again, so don't set the user space flag. B stepping K8s
1441 * sometimes report an truncated RIP for IRET exceptions returning to
1442 * compat mode. Check for these here too.
1443 */
1444 error_kernelspace:
1445 incl %ebx
1446 leaq irq_return(%rip),%rcx
1447 cmpq %rcx,RIP+8(%rsp)
1448 je error_swapgs
1449 movl %ecx,%eax /* zero extend */
1450 cmpq %rax,RIP+8(%rsp)
1451 je bstep_iret
1452 cmpq $gs_change,RIP+8(%rsp)
1453 je error_swapgs
1454 jmp error_sti
1456 bstep_iret:
1457 /* Fix truncated RIP */
1458 movq %rcx,RIP+8(%rsp)
1459 jmp error_swapgs
1460 CFI_ENDPROC
1461 END(error_entry)
1464 /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
1465 ENTRY(error_exit)
1466 DEFAULT_FRAME
1467 movl %ebx,%eax
1468 RESTORE_REST
1469 DISABLE_INTERRUPTS(CLBR_NONE)
1470 TRACE_IRQS_OFF
1471 GET_THREAD_INFO(%rcx)
1472 testl %eax,%eax
1473 jne retint_kernel
1474 LOCKDEP_SYS_EXIT_IRQ
1475 movl TI_flags(%rcx),%edx
1476 movl $_TIF_WORK_MASK,%edi
1477 andl %edi,%edx
1478 jnz retint_careful
1479 jmp retint_swapgs
1480 CFI_ENDPROC
1481 END(error_exit)
1483 /*
1484 * Test if a given stack is an NMI stack or not.
1485 */
1486 .macro test_in_nmi reg stack nmi_ret normal_ret
1487 cmpq %\reg, \stack
1488 ja \normal_ret
1489 subq $EXCEPTION_STKSZ, %\reg
1490 cmpq %\reg, \stack
1491 jb \normal_ret
1492 jmp \nmi_ret
1493 .endm
1495 /* runs on exception stack */
1496 ENTRY(nmi)
1497 INTR_FRAME
1498 PARAVIRT_ADJUST_EXCEPTION_FRAME
1499 /*
1500 * We allow breakpoints in NMIs. If a breakpoint occurs, then
1501 * the iretq it performs will take us out of NMI context.
1502 * This means that we can have nested NMIs where the next
1503 * NMI is using the top of the stack of the previous NMI. We
1504 * can't let it execute because the nested NMI will corrupt the
1505 * stack of the previous NMI. NMI handlers are not re-entrant
1506 * anyway.
1507 *
1508 * To handle this case we do the following:
1509 * Check the a special location on the stack that contains
1510 * a variable that is set when NMIs are executing.
1511 * The interrupted task's stack is also checked to see if it
1512 * is an NMI stack.
1513 * If the variable is not set and the stack is not the NMI
1514 * stack then:
1515 * o Set the special variable on the stack
1516 * o Copy the interrupt frame into a "saved" location on the stack
1517 * o Copy the interrupt frame into a "copy" location on the stack
1518 * o Continue processing the NMI
1519 * If the variable is set or the previous stack is the NMI stack:
1520 * o Modify the "copy" location to jump to the repeate_nmi
1521 * o return back to the first NMI
1522 *
1523 * Now on exit of the first NMI, we first clear the stack variable
1524 * The NMI stack will tell any nested NMIs at that point that it is
1525 * nested. Then we pop the stack normally with iret, and if there was
1526 * a nested NMI that updated the copy interrupt stack frame, a
1527 * jump will be made to the repeat_nmi code that will handle the second
1528 * NMI.
1529 */
1531 /* Use %rdx as out temp variable throughout */
1532 pushq_cfi %rdx
1534 /*
1535 * If %cs was not the kernel segment, then the NMI triggered in user
1536 * space, which means it is definitely not nested.
1537 */
1538 cmpl $__KERNEL_CS, 16(%rsp)
1539 jne first_nmi
1541 /*
1542 * Check the special variable on the stack to see if NMIs are
1543 * executing.
1544 */
1545 cmpl $1, -8(%rsp)
1546 je nested_nmi
1548 /*
1549 * Now test if the previous stack was an NMI stack.
1550 * We need the double check. We check the NMI stack to satisfy the
1551 * race when the first NMI clears the variable before returning.
1552 * We check the variable because the first NMI could be in a
1553 * breakpoint routine using a breakpoint stack.
1554 */
1555 lea 6*8(%rsp), %rdx
1556 test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
1558 nested_nmi:
1559 /*
1560 * Do nothing if we interrupted the fixup in repeat_nmi.
1561 * It's about to repeat the NMI handler, so we are fine
1562 * with ignoring this one.
1563 */
1564 movq $repeat_nmi, %rdx
1565 cmpq 8(%rsp), %rdx
1566 ja 1f
1567 movq $end_repeat_nmi, %rdx
1568 cmpq 8(%rsp), %rdx
1569 ja nested_nmi_out
1571 1:
1572 /* Set up the interrupted NMIs stack to jump to repeat_nmi */
1573 leaq -6*8(%rsp), %rdx
1574 movq %rdx, %rsp
1575 CFI_ADJUST_CFA_OFFSET 6*8
1576 pushq_cfi $__KERNEL_DS
1577 pushq_cfi %rdx
1578 pushfq_cfi
1579 pushq_cfi $__KERNEL_CS
1580 pushq_cfi $repeat_nmi
1582 /* Put stack back */
1583 addq $(11*8), %rsp
1584 CFI_ADJUST_CFA_OFFSET -11*8
1586 nested_nmi_out:
1587 popq_cfi %rdx
1589 /* No need to check faults here */
1590 INTERRUPT_RETURN
1592 first_nmi:
1593 /*
1594 * Because nested NMIs will use the pushed location that we
1595 * stored in rdx, we must keep that space available.
1596 * Here's what our stack frame will look like:
1597 * +-------------------------+
1598 * | original SS |
1599 * | original Return RSP |
1600 * | original RFLAGS |
1601 * | original CS |
1602 * | original RIP |
1603 * +-------------------------+
1604 * | temp storage for rdx |
1605 * +-------------------------+
1606 * | NMI executing variable |
1607 * +-------------------------+
1608 * | Saved SS |
1609 * | Saved Return RSP |
1610 * | Saved RFLAGS |
1611 * | Saved CS |
1612 * | Saved RIP |
1613 * +-------------------------+
1614 * | copied SS |
1615 * | copied Return RSP |
1616 * | copied RFLAGS |
1617 * | copied CS |
1618 * | copied RIP |
1619 * +-------------------------+
1620 * | pt_regs |
1621 * +-------------------------+
1622 *
1623 * The saved RIP is used to fix up the copied RIP that a nested
1624 * NMI may zero out. The original stack frame and the temp storage
1625 * is also used by nested NMIs and can not be trusted on exit.
1626 */
1627 /* Set the NMI executing variable on the stack. */
1628 pushq_cfi $1
1630 /* Copy the stack frame to the Saved frame */
1631 .rept 5
1632 pushq_cfi 6*8(%rsp)
1633 .endr
1635 /* Make another copy, this one may be modified by nested NMIs */
1636 .rept 5
1637 pushq_cfi 4*8(%rsp)
1638 .endr
1640 /* Do not pop rdx, nested NMIs will corrupt it */
1641 movq 11*8(%rsp), %rdx
1643 /*
1644 * Everything below this point can be preempted by a nested
1645 * NMI if the first NMI took an exception. Repeated NMIs
1646 * caused by an exception and nested NMI will start here, and
1647 * can still be preempted by another NMI.
1648 */
1649 restart_nmi:
1650 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1651 subq $ORIG_RAX-R15, %rsp
1652 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1653 /*
1654 * Use save_paranoid to handle SWAPGS, but no need to use paranoid_exit
1655 * as we should not be calling schedule in NMI context.
1656 * Even with normal interrupts enabled. An NMI should not be
1657 * setting NEED_RESCHED or anything that normal interrupts and
1658 * exceptions might do.
1659 */
1660 call save_paranoid
1661 DEFAULT_FRAME 0
1662 /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
1663 movq %rsp,%rdi
1664 movq $-1,%rsi
1665 call do_nmi
1666 testl %ebx,%ebx /* swapgs needed? */
1667 jnz nmi_restore
1668 nmi_swapgs:
1669 SWAPGS_UNSAFE_STACK
1670 nmi_restore:
1671 RESTORE_ALL 8
1672 /* Clear the NMI executing stack variable */
1673 movq $0, 10*8(%rsp)
1674 jmp irq_return
1675 CFI_ENDPROC
1676 END(nmi)
1678 /*
1679 * If an NMI hit an iret because of an exception or breakpoint,
1680 * it can lose its NMI context, and a nested NMI may come in.
1681 * In that case, the nested NMI will change the preempted NMI's
1682 * stack to jump to here when it does the final iret.
1683 */
1684 repeat_nmi:
1685 INTR_FRAME
1686 /* Update the stack variable to say we are still in NMI */
1687 movq $1, 5*8(%rsp)
1689 /* copy the saved stack back to copy stack */
1690 .rept 5
1691 pushq_cfi 4*8(%rsp)
1692 .endr
1694 jmp restart_nmi
1695 CFI_ENDPROC
1696 end_repeat_nmi:
1698 ENTRY(ignore_sysret)
1699 CFI_STARTPROC
1700 mov $-ENOSYS,%eax
1701 sysret
1702 CFI_ENDPROC
1703 END(ignore_sysret)
1705 /*
1706 * End of kprobes section
1707 */
1708 .popsection