| blob | 69cea570858637308d3b7ce2d18211393d7e0804 |
1 /*
2 * very-low-level utilities for runtime support
3 */
5 /*
6 * This software is part of the SBCL system. See the README file for
7 * more information.
8 *
9 * This software is derived from the CMU CL system, which was
10 * written at Carnegie Mellon University and released into the
11 * public domain. The software is in the public domain and is
12 * provided with absolutely no warranty. See the COPYING and CREDITS
13 * files for more information.
14 */
15 \f
16 #ifdef __ELF__
17 // Mark the object as not requiring an executable stack.
18 .section .note.GNU-stack,"",%progbits
19 #endif
21 #include "genesis/sbcl.h"
22 #include "genesis/closure.h"
23 #include "genesis/static-symbols.h"
24 #include "genesis/symbol.h"
25 #include "genesis/thread.h"
27 /* Minimize conditionalization for different OS naming schemes.
28 *
29 * (As of sbcl-0.8.10, this seems no longer to be much of an issue,
30 * since everyone has converged on ELF. If this generality really
31 * turns out not to matter, perhaps it's just clutter we could get
32 * rid of? -- WHN 2004-04-18)
33 *
34 * (Except Win32, which is unlikely ever to be ELF, sorry. -- AB 2005-12-08)
35 */
36 #if defined __linux__ || defined LISP_FEATURE_FREEBSD || defined __NetBSD__ || defined __OpenBSD__ || \
37 defined __sun || defined __DragonFly__
38 #define GNAME(var) var
39 #else
40 #define GNAME(var) _##var
41 #endif
43 /* Get the right type of alignment. Linux, FreeBSD and NetBSD (but not OpenBSD)
44 * want alignment in bytes.
45 *
46 * (As in the GNAME() definitions above, as of sbcl-0.8.10, this seems
47 * no longer to be much of an issue, since everyone has converged on
48 * the same value. If this generality really turns out not to
49 * matter any more, perhaps it's just clutter we could get
50 * rid of? -- WHN 2004-04-18)
51 */
52 #if defined(__linux__) || defined(LISP_FEATURE_FREEBSD) || defined(__NetBSD__) || defined(__OpenBSD__) || \
53 defined(__sun) || defined(LISP_FEATURE_WIN32) || defined(__DragonFly__)
54 #define align_16byte 16
55 #else
56 #define align_16byte 4
57 #endif
59 /*
60 * The assembler used for win32 doesn't like .type or .size directives,
61 * so we want to conditionally kill them out. So let's wrap them in macros
62 * that are defined to be no-ops on win32. Hopefully this still works on
63 * other platforms.
64 */
65 #if !defined(LISP_FEATURE_WIN32) && !defined(LISP_FEATURE_DARWIN)
66 #define TYPE(name) .type name,@function
67 #define SIZE(name) .size name,.-name
68 #else
69 #define TYPE(name)
70 #define SIZE(name)
71 #endif
73 /* Helper macros for access to thread-locals slots for both OS types:
74 * ------------------------------------------------------------------------
75 *
76 * Windows TEB block
77 * ================== __________
78 * | Win32 %FS base | ----> | | 0
79 * ================== | | 1
80 * z z
81 * TLS slots start here> |XXXXXXXX| e10 = TEB_STATIC_TLS_SLOTS_OFFSET
82 * |XXXXXXXX| e11
83 * z ... z
84 * |XXXXXXXX| e4e
85 * TLS ends here> ,- |XXXXXXXX| e4f = TEB_STATIC_TLS_SLOTS_OFFSET+63
86 * / z z
87 * | ---------- "os_address" ----.
88 * | |
89 * | big blob of SBCL-specific thread-local data |
90 * | |----------------------------------------| <--'
91 * | | CONTROL, BINDING, ALIEN STACK |
92 * | z z
93 * ================== | |----------------------------------------|
94 * | Linux %FS base | -->| | FFI stack pointer |
95 * ================== | | (extra page for mprotect) |
96 * \ |----------------------------------------|
97 * (union p_t_d) -----> \-> | struct thread { | dynamic_values[0] |
98 * . | ... | [1] |
99 * . z ... z ... z
100 * [tls data begins] | } | ... | <-
101 * [declared end of p_t_d] |----------------------------------------| . |
102 * . | ... | . |
103 * . | [TLS_SIZE-1] | <-|
104 * [tls data actually ends] |----------------------------------------| |
105 * . | ALTSTACK | |
106 * . |----------------------------------------| |
107 * . | struct nonpointer_thread_data { } | |
108 * . ------------------------------------------ |
109 * [blob actually ends] |
110 * /
111 * /
112 * /
113 * ______________________ /
114 * | struct symbol { | /
115 * z ... z /
116 * | fixnum tls_index; // fixnum value relative to union /
117 * | } | (< TLS_SIZE = 4096)
118 * ---------------------|
119 */
120 #ifdef LISP_FEATURE_WIN32
121 # define TEB_STATIC_TLS_SLOTS_OFFSET 0xE10
122 # define TEB_SBCL_THREAD_BASE_OFFSET (TEB_STATIC_TLS_SLOTS_OFFSET+(63*4))
123 # define SBCL_THREAD_BASE_EA %fs:TEB_SBCL_THREAD_BASE_OFFSET
124 # define MAYBE_FS(addr) addr
125 # define LoadTlSymbolValueAddress(symbol,reg) ; \
126 movl SBCL_THREAD_BASE_EA, reg ; \
127 addl (symbol+SYMBOL_TLS_INDEX_OFFSET), reg ;
128 # define LoadCurrentThreadSlot(offset,reg); \
129 movl SBCL_THREAD_BASE_EA, reg ; \
130 movl offset(reg), reg ;
131 #elif !defined(LISP_FEATURE_SB_THREAD)
132 /* so that we don't have to rewrite the safepoint logic */
133 # define SBCL_THREAD_BASE_EA GNAME(all_threads)
134 # define MAYBE_FS(addr) addr
135 #elif defined(LISP_FEATURE_LINUX) || defined(LISP_FEATURE_SUNOS) || defined(LISP_FEATURE_FREEBSD) || \
136 defined(LISP_FEATURE_DRAGONFLY)
137 /* %fs:0 refers to the current thread. Useful! Less usefully,
138 * Linux/x86 isn't capable of reporting a faulting si_addr on a
139 * segment as defined above (whereas faults on the segment that %gs
140 * usually points are reported just fine...).
141 * But we have the thread's address stored in the THIS slot,
142 * so that within the thread
143 * movl %fs:THIS_OFFSET,x
144 * stores the absolute address of %fs:0 into x.
145 */
146 # define SBCL_THREAD_BASE_EA %fs:THREAD_THIS_OFFSET
147 # define MAYBE_FS(addr) addr
148 #else
149 /* perhaps there's an OS out there that actually supports %fs without
150 * jumping through hoops, so just in case, here a default definition: */
151 # define SBCL_THREAD_BASE_EA $0
152 # define MAYBE_FS(addr) %fs:addr
153 #endif
156 /* the CSP page sits right before the thread */
157 #define THREAD_SAVED_CSP_OFFSET (-N_WORD_BYTES)
159 #ifdef LISP_FEATURE_UD2_BREAKPOINTS
160 #define TRAP ud2
161 #else
162 #define TRAP int3
163 #endif
165 .text
166 .globl GNAME(all_threads)
167 \f
168 /*
169 * A call to call_into_c preserves esi, edi, and ebp.
170 * (The C function will preserve ebx, esi, edi, and ebp across its
171 * function call, but we trash ebx ourselves by using it to save the
172 * return Lisp address.)
173 *
174 * Return values are in eax and maybe edx for quads, or st(0) for
175 * floats.
176 *
177 * This should work for Lisp calls C calls Lisp calls C..
178 *
179 * FIXME & OAOOM: This duplicates call-out in src/compiler/x86/c-call.lisp,
180 * so if you tweak this, change that too!
181 */
182 /*
183 * Note on sections specific to LISP_FEATURE_SB_SAFEPOINT:
184 *
185 * The code below is essential to safepoint-based garbage collection,
186 * and several details need to be considered for correct implementation.
187 *
188 * The stack spilling approach:
189 * On SB-SAFEPOINT platforms, the CALL-OUT vop is defined to spill all
190 * live Lisp TNs to the stack to provide information for conservative
191 * GC cooperatively (avoiding the need to retrieve register values
192 * from POSIX signal contexts or Windows GetThreadContext()).
193 *
194 * Finding the SP at all:
195 * The main remaining value needed by GC is the stack pointer (SP) at
196 * the moment of entering the foreign function. For this purpose, a
197 * thread-local field for the SP is used. Two stores to that field
198 * are done for each C call, one to save the SP before calling out and
199 * and one to undo that store afterwards.
200 *
201 * Stores as synchronization points:
202 * These two stores delimit the C call: While the SP is set, our
203 * thread is known not to run Lisp code: During GC, memory protection
204 * ensures that no thread proceeds across stores.
205 *
206 * The return PC issue:
207 * (Note that CALL-OUT has, in principle, two versions: Inline
208 * assembly in the VOP -or- alternatively the out-of-line version you
209 * are currently reading. In reality, safepoint builds currently
210 * lack the inline code entirely.)
211 *
212 * Both versions need to take special care with the return PC:
213 * - In the inline version of the code (if it existed), the two stores
214 * would be done directly in the CALL-OUT vop. In that theoretical
215 * implementation, even though the CALL instruction pushes the return
216 * address to the stack, it is outside of the range preserved by the
217 * GC as possible heap pointers.
218 * - In this out-of-line version, the stores are done during
219 * call_into_c's frame, but an equivalent problem arises: In order
220 * to present the stack of arguments as our foreign function expects
221 * them, call_into_c has to pop the Lisp return address into a
222 * register.
223 * In both cases, stack scanning would not normally find the return
224 * address, so we arrange to store it in a slot within our calling
225 * frame. The address of this slot is passed to us in EDI.
226 *
227 * Note on look-alike accessor macros with vastly different behaviour:
228 * THREAD_PC_AROUND_FOREIGN_CALL_OFFSET was an "ordinary" field of the
229 * struct thread, whereas THREAD_SAVED_CSP_OFFSET is a synchronization
230 * point on a potentially write-protected page.
231 */
233 .text
234 .align align_16byte,0x90
235 .globl GNAME(call_into_c)
236 TYPE(GNAME(call_into_c))
237 GNAME(call_into_c):
238 /* Save the return Lisp address in ebx. */
239 popl %ebx
241 /* Setup the NPX for C */
242 /* The VOP says regarding CLD: "Clear out DF: Darwin, Windows,
243 * and Solaris at least require this, and it should not hurt
244 * others either." call_into_c didn't have it, but better safe than
245 * sorry. */
246 cld
247 fstp %st(0)
248 fstp %st(0)
249 fstp %st(0)
250 fstp %st(0)
251 fstp %st(0)
252 fstp %st(0)
253 fstp %st(0)
254 fstp %st(0)
256 #ifdef LISP_FEATURE_SB_SAFEPOINT
257 /* Save our return PC in the allocated slot (address passed in EDI) */
258 movl %ebx,(%edi)
259 /* enter safe region: store SP */
260 movl SBCL_THREAD_BASE_EA,%edi
261 movl %esp,MAYBE_FS(THREAD_SAVED_CSP_OFFSET(%edi))
262 #endif
264 /* foreign call, preserving ESI, EDI, and EBX */
265 call *%eax # normal callout using Lisp stack
266 /* return values now in eax/edx OR st(0) */
268 #ifdef LISP_FEATURE_SB_SAFEPOINT
269 /* leave region: clear the SP! */
270 xorl %ecx,%ecx
271 movl %ecx,MAYBE_FS(THREAD_SAVED_CSP_OFFSET(%edi))
272 #endif
274 movl %eax,%ecx # remember integer return value
276 /* Check for a return FP value. */
277 fxam
278 fnstsw %ax
279 andl $0x4500,%eax
280 cmpl $0x4100,%eax
281 jne Lfp_rtn_value
283 /* The return value is in eax, or eax,edx? */
284 /* Set up the NPX stack for Lisp. */
285 fldz # Ensure no regs are empty.
286 fldz
287 fldz
288 fldz
289 fldz
290 fldz
291 fldz
292 fldz
294 /* Restore the return value. */
295 movl %ecx,%eax # maybe return value
297 /* Return. */
298 jmp *%ebx
300 Lfp_rtn_value:
301 /* The return result is in st(0). */
302 /* Set up the NPX stack for Lisp, placing the result in st(0). */
303 fldz # Ensure no regs are empty.
304 fldz
305 fldz
306 fldz
307 fldz
308 fldz
309 fldz
310 fxch %st(7) # Move the result back to st(0).
312 /* We don't need to restore eax, because the result is in st(0). */
314 /* Return. FIXME: It would be nice to restructure this to use RET. */
315 jmp *%ebx
317 SIZE(GNAME(call_into_c))
319 \f
320 #ifdef LISP_FEATURE_OS_THREAD_STACK
321 .text
322 .globl GNAME(funcall1_switching_stack)
323 TYPE(GNAME(funcall1_switching_stack))
324 .align align_16byte,0x90
325 GNAME(funcall1_switching_stack):
326 /* The arguments are switched, funcall1_switching_stack(arg, function)
327 to avoid shuffling registers on x86-64
328 */
329 push %ebp
330 mov %esp,%ebp
332 movl 8(%ebp),%eax # arg
333 movl 12(%ebp),%edx # function
335 mov THREAD_CONTROL_STACK_END_OFFSET(%eax),%esp
336 push %edx
337 push %eax
338 call *%edx
340 mov %ebp, %esp
341 pop %ebp
342 ret
343 SIZE(GNAME(funcall1_switching_stack))
344 #endif
346 .text
347 .globl GNAME(call_into_lisp_first_time)
348 TYPE(GNAME(call_into_lisp_first_time))
350 /* We don't worry too much about saving registers
351 * here, because we never expect to return from the initial call to lisp
352 * anyway */
354 .align align_16byte,0x90
355 GNAME(call_into_lisp_first_time):
356 GNAME(lspmain):
357 pushl %ebp # Save old frame pointer.
358 movl %esp,%ebp # Establish new frame.
359 #ifndef LISP_FEATURE_WIN32
360 movl GNAME(all_threads),%eax
361 /* pthread machinery takes care of this for other threads */
362 movl THREAD_CONTROL_STACK_END_OFFSET(%eax) ,%esp
363 #else
364 /* Win32 -really- doesn't like you switching stacks out from under it. */
365 movl GNAME(all_threads),%eax
366 #endif
367 jmp Lstack
368 \f
369 .text
370 .globl GNAME(call_into_lisp)
371 TYPE(GNAME(call_into_lisp))
373 /* The C conventions require that ebx, esi, edi, and ebp be preserved
374 * across function calls. */
376 .align align_16byte,0x90
377 GNAME(call_into_lisp):
378 pushl %ebp # Save old frame pointer.
379 movl %esp,%ebp # Establish new frame.
381 Lstack:
382 /* Save the NPX state */
383 fwait # Catch any pending NPX exceptions.
384 subl $108,%esp # Make room for the NPX state.
385 fnsave (%esp) # save and reset NPX
387 movl (%esp),%eax # Load NPX control word.
388 andl $0xfffff2ff,%eax # Set rounding mode to nearest.
389 orl $0x00000200,%eax # Set precision to 64 bits. (53-bit mantissa)
390 pushl %eax
391 fldcw (%esp) # Recover modes.
392 popl %eax
394 fldz # Ensure no FP regs are empty.
395 fldz
396 fldz
397 fldz
398 fldz
399 fldz
400 fldz
401 fldz
403 /* Save C regs: ebx esi edi. */
404 pushl %ebx
405 pushl %esi
406 pushl %edi
408 /* Clear descriptor regs. */
409 xorl %eax,%eax # lexenv
410 xorl %ebx,%ebx # available
411 xorl %ecx,%ecx # arg count
412 xorl %edx,%edx # first arg
413 xorl %edi,%edi # second arg
414 xorl %esi,%esi # third arg
416 /* Establish Lisp args. */
417 movl 8(%ebp),%eax # lexenv?
418 movl 12(%ebp),%ebx # address of arg vec
419 movl 16(%ebp),%ecx # num args
420 shll $2,%ecx # Make num args into fixnum.
421 cmpl $0,%ecx
422 je Ldone
423 movl (%ebx),%edx # arg0
424 cmpl $4,%ecx
425 je Ldone
426 movl 4(%ebx),%edi # arg1
427 cmpl $8,%ecx
428 je Ldone
429 movl 8(%ebx),%esi # arg2
430 Ldone:
431 /* Registers eax, ecx, edx, edi, and esi are now live. */
433 #ifdef LISP_FEATURE_WIN32
434 /* Establish an SEH frame. */
435 #ifdef LISP_FEATURE_SB_THREAD
436 /* Save binding stack pointer */
437 subl $4, %esp
438 pushl %eax
439 movl SBCL_THREAD_BASE_EA, %eax
440 movl THREAD_BINDING_STACK_POINTER_OFFSET(%eax), %eax
441 movl %eax, 4(%esp)
442 popl %eax
443 #else
444 pushl BINDING_STACK_POINTER + SYMBOL_VALUE_OFFSET
445 #endif
446 pushl $GNAME(exception_handler_wrapper)
447 pushl %fs:0
448 movl %esp, %fs:0
449 #endif
451 /* Alloc new frame. */
452 push %ebp # Dummy for return address
453 push %ebp # fp in save location S1
454 mov %esp,%ebp # The current sp marks start of new frame.
455 sub $4,%esp # Ensure 3 slots are allocated, two above.
457 call *CLOSURE_FUN_OFFSET(%eax)
459 /* If the function returned multiple values, it will return to
460 this point. Lose them */
461 jnc LsingleValue
462 mov %ebx, %esp
463 LsingleValue:
464 /* A singled value function returns here */
466 #ifdef LISP_FEATURE_WIN32
467 /* Remove our SEH frame. */
468 mov %fs:0,%esp
469 popl %fs:0
470 add $8, %esp
471 #endif
473 /* Restore C regs: ebx esi edi. */
474 popl %edi
475 popl %esi
476 popl %ebx
478 /* Restore the NPX state. */
479 frstor (%esp)
480 addl $108, %esp
482 popl %ebp # c-sp
483 movl %edx,%eax # c-val
484 ret
485 SIZE(GNAME(call_into_lisp))
486 \f
487 /* support for saving and restoring the NPX state from C */
488 .text
489 .globl GNAME(fpu_save)
490 TYPE(GNAME(fpu_save))
491 .align 2,0x90
492 GNAME(fpu_save):
493 movl 4(%esp),%eax
494 fnsave (%eax) # Save the NPX state. (resets NPX)
495 ret
496 SIZE(GNAME(fpu_save))
498 .globl GNAME(fpu_restore)
499 TYPE(GNAME(fpu_restore))
500 .align 2,0x90
501 GNAME(fpu_restore):
502 movl 4(%esp),%eax
503 frstor (%eax) # Restore the NPX state.
504 ret
505 SIZE(GNAME(fpu_restore))
506 \f
507 /*
508 * fun-end breakpoint magic
509 */
511 /*
512 * For an explanation of the magic involved in function-end
513 * breakpoints, see the implementation in ppc-assem.S.
514 */
516 .text
517 .globl GNAME(fun_end_breakpoint_guts)
518 .align align_16byte
519 GNAME(fun_end_breakpoint_guts):
520 /* Multiple Value return */
521 jc multiple_value_return
522 /* Single value return: The eventual return will now use the
523 multiple values return convention but with a return values
524 count of one. */
525 movl %esp,%ebx # Setup ebx - the ofp.
526 subl $4,%esp # Allocate one stack slot for the return value
527 movl $(1 << N_FIXNUM_TAG_BITS),%ecx # Setup ecx for one return value.
528 movl $(NIL),%edi # default second value
529 movl $(NIL),%esi # default third value
531 multiple_value_return:
533 .globl GNAME(fun_end_breakpoint_trap)
534 GNAME(fun_end_breakpoint_trap):
535 TRAP
536 .byte trap_FunEndBreakpoint
537 hlt # We should never return here.
539 .globl GNAME(fun_end_breakpoint_end)
540 GNAME(fun_end_breakpoint_end):
542 \f
543 .globl GNAME(do_pending_interrupt)
544 TYPE(GNAME(do_pending_interrupt))
545 .align align_16byte,0x90
546 GNAME(do_pending_interrupt):
547 TRAP
548 .byte trap_PendingInterrupt
549 ret
550 SIZE(GNAME(do_pending_interrupt))
551 \f
552 #ifdef LISP_FEATURE_SB_SAFEPOINT
553 .globl GNAME(handle_global_safepoint_violation)
554 TYPE(GNAME(handle_global_safepoint_violation))
555 .align align_16byte,0x90
556 GNAME(handle_global_safepoint_violation):
557 TRAP
558 .byte trap_GlobalSafepoint
559 ret
560 SIZE(GNAME(handle_global_safepoint_violation))
562 .globl GNAME(handle_csp_safepoint_violation)
563 TYPE(GNAME(handle_csp_safepoint_violation))
564 .align align_16byte,0x90
565 GNAME(handle_csp_safepoint_violation):
566 TRAP
567 .byte trap_CspSafepoint
568 ret
569 SIZE(GNAME(handle_csp_safepoint_violation))
570 #endif /* SB-SAFEPOINT */
571 \f
572 .globl GNAME(memory_fault_emulation_trap)
573 TYPE(GNAME(memory_fault_emulation_trap))
574 .align align_16byte,0x90
575 GNAME(memory_fault_emulation_trap):
576 TRAP
577 .byte trap_MemoryFaultEmulation
578 SIZE(GNAME(memory_fault_emulation_trap))
579 \f
580 #ifdef LISP_FEATURE_WIN32
581 /* The guts of the exception-handling system doesn't use
582 * frame pointers, which manages to throw off backtraces
583 * rather badly. So here we grab the (known-good) EBP
584 * and EIP from the exception context and use it to fake
585 * up a stack frame which will skip over the system SEH
586 * code. */
587 .align align_16byte
588 .globl GNAME(exception_handler_wrapper)
589 TYPE(GNAME(exception_handler_wrapper))
590 GNAME(exception_handler_wrapper):
591 /* Context layout is: */
592 /* 7 dwords before FSA. (0x1c) */
593 /* 8 dwords and 0x50 bytes in the FSA. (0x70/0x8c) */
594 /* 4 dwords segregs. (0x10/0x9c) */
595 /* 6 dwords non-stack GPRs. (0x18/0xb4) */
596 /* EBP (at 0xb4) */
597 /* EIP (at 0xb8) */
598 #define CONTEXT_EBP_OFFSET 0xb4
599 #define CONTEXT_EIP_OFFSET 0xb8
600 /* some other stuff we don't care about. */
601 pushl %ebp
602 movl 0x10(%esp), %ebp /* context */
603 pushl CONTEXT_EIP_OFFSET(%ebp)
604 pushl CONTEXT_EBP_OFFSET(%ebp)
605 movl %esp, %ebp
606 pushl 0x1c(%esp)
607 pushl 0x1c(%esp)
608 pushl 0x1c(%esp)
609 pushl 0x1c(%esp)
610 call GNAME(handle_exception)
611 lea 8(%ebp), %esp
612 popl %ebp
613 ret
614 SIZE(GNAME(exception_handler_wrapper))
615 #endif
617 #ifdef LISP_FEATURE_DARWIN
618 .align align_16byte
619 .globl GNAME(call_into_lisp_tramp)
620 TYPE(GNAME(call_into_lisp_tramp))
621 GNAME(call_into_lisp_tramp):
622 /* 1. build the stack frame from the block that's pointed to by ECX
623 2. free the block
624 3. set ECX to 0
625 4. call the function via call_into_lisp
626 */
627 pushl 0(%ecx) /* return address */
629 pushl %ebp
630 movl %esp, %ebp
632 pushl 32(%ecx) /* eflags */
633 pushl 28(%ecx) /* EAX */
634 pushl 20(%ecx) /* ECX */
635 pushl 16(%ecx) /* EDX */
636 pushl 24(%ecx) /* EBX */
637 pushl $0 /* popal is going to ignore esp */
638 pushl %ebp /* is this right?? */
639 pushl 12(%ecx) /* ESI */
640 pushl 8(%ecx) /* EDI */
641 pushl $0 /* args for call_into_lisp */
642 pushl $0
643 pushl 4(%ecx) /* function to call */
645 /* free our save block */
646 pushl %ecx /* reserve sufficient space on stack for args */
647 pushl %ecx
648 andl $0xfffffff0, %esp /* align stack */
649 movl $0x40, 4(%esp)
650 movl %ecx, (%esp)
651 call GNAME(os_alloc_gc_space)
653 /* call call_into_lisp */
654 leal -48(%ebp), %esp
655 call GNAME(call_into_lisp)
657 /* Clean up our mess */
658 leal -36(%ebp), %esp
659 popal
660 popfl
661 leave
662 ret
664 SIZE(call_into_lisp_tramp)
665 #endif
667 .align align_16byte,0x90
668 .globl GNAME(post_signal_tramp)
669 TYPE(GNAME(post_signal_tramp))
670 GNAME(post_signal_tramp):
671 /* this is notionally the second half of a function whose first half
672 * doesn't exist. This is where call_into_lisp returns when called
673 * using return_to_lisp_function */
674 addl $12,%esp /* clear call_into_lisp args from stack */
675 popal /* restore registers */
676 popfl
677 #ifdef LISP_FEATURE_DARWIN
678 /* skip two padding words */
679 addl $8,%esp
680 #endif
681 leave
682 ret
683 SIZE(GNAME(post_signal_tramp))
685 \f
686 /* When LISP_FEATURE_C_STACK_IS_CONTROL_STACK, we cannot safely scrub
687 * the control stack from C, largely due to not knowing where the
688 * active stack frame ends. On such platforms, we reimplement the
689 * core scrubbing logic in assembly, in this case here:
690 */
691 .text
692 .align align_16byte,0x90
693 .globl GNAME(arch_scrub_control_stack)
694 TYPE(GNAME(arch_scrub_control_stack))
695 GNAME(arch_scrub_control_stack):
696 /* We are passed three parameters:
697 * A (struct thread *) at [ESP+4],
698 * the address of the guard page at [ESP+8], and
699 * the address of the hard guard page at [ESP+12].
700 * We may trash EAX, ECX, and EDX with impunity.
701 * [ESP] is our return address, [ESP-4] is the first
702 * stack slot to scrub. */
704 /* We start by setting up our scrub pointer in EAX, our
705 * guard page upper bound in ECX, and our hard guard
706 * page upper bound in EDX. */
707 lea -4(%esp), %eax
708 mov GNAME(os_vm_page_size),%edx
709 mov %edx, %ecx
710 add 8(%esp), %ecx
711 add 12(%esp), %edx
713 /* We need to do a memory operation relative to the
714 * thread pointer, so put it in %ecx and our guard
715 * page upper bound in 4(%esp). */
716 xchg 4(%esp), %ecx
718 /* Now we begin our main scrub loop. */
719 ascs_outer_loop:
721 /* If we're about to scrub the hard guard page, exit. */
722 cmp %edx, %eax
723 jae ascs_check_guard_page
724 cmp 12(%esp), %eax
725 ja ascs_finished
727 ascs_check_guard_page:
728 /* If we're about to scrub the guard page, and the guard
729 * page is protected, exit. */
730 cmp 4(%esp), %eax
731 jae ascs_clear_loop
732 cmp 8(%esp), %eax
733 jbe ascs_clear_loop
734 /* test state_word.control_stack_guard_page_protected */
735 cmpb $0, THREAD_STATE_WORD_OFFSET(%ecx)
736 jne ascs_finished
738 /* Clear memory backwards to the start of the (4KiB) page */
739 ascs_clear_loop:
740 movl $0, (%eax)
741 test $0xfff, %eax
742 lea -4(%eax), %eax
743 jnz ascs_clear_loop
745 /* If we're about to hit the hard guard page, exit. */
746 cmp %edx, %eax
747 jae ascs_finished
749 /* If the next (previous?) 4KiB page contains a non-zero
750 * word, continue scrubbing. */
751 ascs_check_loop:
752 testl $-1, (%eax)
753 jnz ascs_outer_loop
754 test $0xfff, %eax
755 lea -4(%eax), %eax
756 jnz ascs_check_loop
758 ascs_finished:
759 ret
760 SIZE(GNAME(arch_scrub_control_stack))