]>
Commit | Line | Data |
---|---|---|
7458026b | 1 | /* Library support for -fsplit-stack. */ |
8d9254fc | 2 | /* Copyright (C) 2009-2020 Free Software Foundation, Inc. |
7458026b ILT |
3 | Contributed by Ian Lance Taylor <iant@google.com>. |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | Under Section 7 of GPL version 3, you are granted additional | |
18 | permissions described in the GCC Runtime Library Exception, version | |
19 | 3.1, as published by the Free Software Foundation. | |
20 | ||
21 | You should have received a copy of the GNU General Public License and | |
22 | a copy of the GCC Runtime Library Exception along with this program; | |
23 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
24 | <http://www.gnu.org/licenses/>. */ | |
25 | ||
aac9480d MS |
26 | #pragma GCC optimize ("no-isolate-erroneous-paths-dereference") |
27 | ||
0f0fd745 AM |
28 | /* powerpc 32-bit not supported. */ |
29 | #if !defined __powerpc__ || defined __powerpc64__ | |
30 | ||
7458026b ILT |
31 | #include "tconfig.h" |
32 | #include "tsystem.h" | |
33 | #include "coretypes.h" | |
34 | #include "tm.h" | |
852b75ed | 35 | #include "libgcc_tm.h" |
7458026b | 36 | |
67914693 | 37 | /* If inhibit_libc is defined, we cannot compile this file. The |
7458026b ILT |
38 | effect is that people will not be able to use -fsplit-stack. That |
39 | is much better than failing the build particularly since people | |
40 | will want to define inhibit_libc while building a compiler which | |
41 | can build glibc. */ | |
42 | ||
43 | #ifndef inhibit_libc | |
44 | ||
45 | #include <assert.h> | |
46 | #include <errno.h> | |
47 | #include <signal.h> | |
48 | #include <stdlib.h> | |
e14304ef | 49 | #include <string.h> |
7458026b ILT |
50 | #include <unistd.h> |
51 | #include <sys/mman.h> | |
52 | #include <sys/uio.h> | |
53 | ||
54 | #include "generic-morestack.h" | |
55 | ||
710d54ed ILT |
56 | /* Some systems use LD_PRELOAD or similar tricks to add hooks to |
57 | mmap/munmap. That breaks this code, because when we call mmap | |
58 | there is enough stack space for the system call but there is not, | |
59 | in general, enough stack space to run a hook. At least when using | |
60 | glibc on GNU/Linux we can avoid the problem by calling __mmap and | |
61 | __munmap. */ | |
62 | ||
458ca332 | 63 | #if defined(__gnu_linux__) && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 26)) |
710d54ed ILT |
64 | |
65 | extern void *__mmap (void *, size_t, int, int, int, off_t); | |
66 | extern int __munmap (void *, size_t); | |
67 | ||
68 | #define mmap __mmap | |
69 | #define munmap __munmap | |
70 | ||
71 | #endif /* defined(__gnu_linux__) */ | |
72 | ||
e14304ef ILT |
73 | typedef unsigned uintptr_type __attribute__ ((mode (pointer))); |
74 | ||
7458026b ILT |
75 | /* This file contains subroutines that are used by code compiled with |
76 | -fsplit-stack. */ | |
77 | ||
78 | /* Declare functions to avoid warnings--there is no header file for | |
79 | these internal functions. We give most of these functions the | |
80 | flatten attribute in order to minimize their stack usage--here we | |
81 | must minimize stack usage even at the cost of code size, and in | |
82 | general inlining everything will do that. */ | |
83 | ||
84 | extern void | |
85 | __generic_morestack_set_initial_sp (void *sp, size_t len) | |
86 | __attribute__ ((no_split_stack, flatten, visibility ("hidden"))); | |
87 | ||
88 | extern void * | |
89 | __generic_morestack (size_t *frame_size, void *old_stack, size_t param_size) | |
90 | __attribute__ ((no_split_stack, flatten, visibility ("hidden"))); | |
91 | ||
92 | extern void * | |
93 | __generic_releasestack (size_t *pavailable) | |
94 | __attribute__ ((no_split_stack, flatten, visibility ("hidden"))); | |
95 | ||
96 | extern void | |
97 | __morestack_block_signals (void) | |
98 | __attribute__ ((no_split_stack, flatten, visibility ("hidden"))); | |
99 | ||
100 | extern void | |
101 | __morestack_unblock_signals (void) | |
102 | __attribute__ ((no_split_stack, flatten, visibility ("hidden"))); | |
103 | ||
104 | extern size_t | |
105 | __generic_findstack (void *stack) | |
106 | __attribute__ ((no_split_stack, flatten, visibility ("hidden"))); | |
107 | ||
108 | extern void | |
109 | __morestack_load_mmap (void) | |
110 | __attribute__ ((no_split_stack, visibility ("hidden"))); | |
111 | ||
112 | extern void * | |
113 | __morestack_allocate_stack_space (size_t size) | |
114 | __attribute__ ((visibility ("hidden"))); | |
115 | ||
e14304ef ILT |
116 | /* These are functions which -fsplit-stack code can call. These are |
117 | not called by the compiler, and are not hidden. FIXME: These | |
118 | should be in some header file somewhere, somehow. */ | |
7458026b ILT |
119 | |
120 | extern void * | |
121 | __splitstack_find (void *, void *, size_t *, void **, void **, void **) | |
122 | __attribute__ ((visibility ("default"))); | |
123 | ||
e14304ef ILT |
124 | extern void |
125 | __splitstack_block_signals (int *, int *) | |
126 | __attribute__ ((visibility ("default"))); | |
127 | ||
128 | extern void | |
129 | __splitstack_getcontext (void *context[10]) | |
130 | __attribute__ ((no_split_stack, visibility ("default"))); | |
131 | ||
132 | extern void | |
133 | __splitstack_setcontext (void *context[10]) | |
134 | __attribute__ ((no_split_stack, visibility ("default"))); | |
135 | ||
136 | extern void * | |
137 | __splitstack_makecontext (size_t, void *context[10], size_t *) | |
138 | __attribute__ ((visibility ("default"))); | |
139 | ||
a01207c4 ILT |
140 | extern void * |
141 | __splitstack_resetcontext (void *context[10], size_t *) | |
142 | __attribute__ ((visibility ("default"))); | |
143 | ||
144 | extern void | |
145 | __splitstack_releasecontext (void *context[10]) | |
146 | __attribute__ ((visibility ("default"))); | |
147 | ||
e14304ef ILT |
148 | extern void |
149 | __splitstack_block_signals_context (void *context[10], int *, int *) | |
150 | __attribute__ ((visibility ("default"))); | |
151 | ||
152 | extern void * | |
153 | __splitstack_find_context (void *context[10], size_t *, void **, void **, | |
154 | void **) | |
155 | __attribute__ ((visibility ("default"))); | |
156 | ||
157 | /* These functions must be defined by the processor specific code. */ | |
158 | ||
159 | extern void *__morestack_get_guard (void) | |
160 | __attribute__ ((no_split_stack, visibility ("hidden"))); | |
161 | ||
162 | extern void __morestack_set_guard (void *) | |
163 | __attribute__ ((no_split_stack, visibility ("hidden"))); | |
164 | ||
165 | extern void *__morestack_make_guard (void *, size_t) | |
166 | __attribute__ ((no_split_stack, visibility ("hidden"))); | |
167 | ||
7458026b ILT |
168 | /* When we allocate a stack segment we put this header at the |
169 | start. */ | |
170 | ||
171 | struct stack_segment | |
172 | { | |
173 | /* The previous stack segment--when a function running on this stack | |
174 | segment returns, it will run on the previous one. */ | |
175 | struct stack_segment *prev; | |
176 | /* The next stack segment, if it has been allocated--when a function | |
177 | is running on this stack segment, the next one is not being | |
178 | used. */ | |
179 | struct stack_segment *next; | |
180 | /* The total size of this stack segment. */ | |
181 | size_t size; | |
182 | /* The stack address when this stack was created. This is used when | |
183 | popping the stack. */ | |
184 | void *old_stack; | |
185 | /* A list of memory blocks allocated by dynamic stack | |
186 | allocation. */ | |
187 | struct dynamic_allocation_blocks *dynamic_allocation; | |
188 | /* A list of dynamic memory blocks no longer needed. */ | |
189 | struct dynamic_allocation_blocks *free_dynamic_allocation; | |
190 | /* An extra pointer in case we need some more information some | |
191 | day. */ | |
192 | void *extra; | |
193 | }; | |
194 | ||
195 | /* This structure holds the (approximate) initial stack pointer and | |
196 | size for the system supplied stack for a thread. This is set when | |
197 | the thread is created. We also store a sigset_t here to hold the | |
198 | signal mask while splitting the stack, since we don't want to store | |
199 | that on the stack. */ | |
200 | ||
201 | struct initial_sp | |
202 | { | |
203 | /* The initial stack pointer. */ | |
204 | void *sp; | |
205 | /* The stack length. */ | |
206 | size_t len; | |
207 | /* A signal mask, put here so that the thread can use it without | |
208 | needing stack space. */ | |
209 | sigset_t mask; | |
e14304ef ILT |
210 | /* Non-zero if we should not block signals. This is a reversed flag |
211 | so that the default zero value is the safe value. The type is | |
212 | uintptr_type because it replaced one of the void * pointers in | |
213 | extra. */ | |
214 | uintptr_type dont_block_signals; | |
7458026b | 215 | /* Some extra space for later extensibility. */ |
e14304ef | 216 | void *extra[4]; |
7458026b ILT |
217 | }; |
218 | ||
219 | /* A list of memory blocks allocated by dynamic stack allocation. | |
220 | This is used for code that calls alloca or uses variably sized | |
221 | arrays. */ | |
222 | ||
223 | struct dynamic_allocation_blocks | |
224 | { | |
225 | /* The next block in the list. */ | |
226 | struct dynamic_allocation_blocks *next; | |
227 | /* The size of the allocated memory. */ | |
228 | size_t size; | |
229 | /* The allocated memory. */ | |
230 | void *block; | |
231 | }; | |
232 | ||
233 | /* These thread local global variables must be shared by all split | |
234 | stack code across shared library boundaries. Therefore, they have | |
235 | default visibility. They have extensibility fields if needed for | |
236 | new versions. If more radical changes are needed, new code can be | |
237 | written using new variable names, while still using the existing | |
238 | variables in a backward compatible manner. Symbol versioning is | |
239 | also used, although, since these variables are only referenced by | |
240 | code in this file and generic-morestack-thread.c, it is likely that | |
241 | simply using new names will suffice. */ | |
242 | ||
243 | /* The first stack segment allocated for this thread. */ | |
244 | ||
245 | __thread struct stack_segment *__morestack_segments | |
246 | __attribute__ ((visibility ("default"))); | |
247 | ||
248 | /* The stack segment that we think we are currently using. This will | |
249 | be correct in normal usage, but will be incorrect if an exception | |
250 | unwinds into a different stack segment or if longjmp jumps to a | |
251 | different stack segment. */ | |
252 | ||
253 | __thread struct stack_segment *__morestack_current_segment | |
254 | __attribute__ ((visibility ("default"))); | |
255 | ||
256 | /* The initial stack pointer and size for this thread. */ | |
257 | ||
258 | __thread struct initial_sp __morestack_initial_sp | |
259 | __attribute__ ((visibility ("default"))); | |
260 | ||
261 | /* A static signal mask, to avoid taking up stack space. */ | |
262 | ||
263 | static sigset_t __morestack_fullmask; | |
264 | ||
1f3fa525 TM |
265 | /* Page size, as returned from getpagesize(). Set on startup. */ |
266 | static unsigned int static_pagesize; | |
267 | ||
268 | /* Set on startup to non-zero value if SPLIT_STACK_GUARD env var is set. */ | |
269 | static int use_guard_page; | |
270 | ||
7458026b ILT |
271 | /* Convert an integer to a decimal string without using much stack |
272 | space. Return a pointer to the part of the buffer to use. We this | |
273 | instead of sprintf because sprintf will require too much stack | |
274 | space. */ | |
275 | ||
276 | static char * | |
277 | print_int (int val, char *buf, int buflen, size_t *print_len) | |
278 | { | |
279 | int is_negative; | |
280 | int i; | |
281 | unsigned int uval; | |
282 | ||
283 | uval = (unsigned int) val; | |
284 | if (val >= 0) | |
285 | is_negative = 0; | |
286 | else | |
287 | { | |
288 | is_negative = 1; | |
289 | uval = - uval; | |
290 | } | |
291 | ||
292 | i = buflen; | |
293 | do | |
294 | { | |
295 | --i; | |
296 | buf[i] = '0' + (uval % 10); | |
297 | uval /= 10; | |
298 | } | |
299 | while (uval != 0 && i > 0); | |
300 | ||
301 | if (is_negative) | |
302 | { | |
303 | if (i > 0) | |
304 | --i; | |
305 | buf[i] = '-'; | |
306 | } | |
307 | ||
308 | *print_len = buflen - i; | |
309 | return buf + i; | |
310 | } | |
311 | ||
312 | /* Print the string MSG/LEN, the errno number ERR, and a newline on | |
313 | stderr. Then crash. */ | |
314 | ||
315 | void | |
316 | __morestack_fail (const char *, size_t, int) __attribute__ ((noreturn)); | |
317 | ||
318 | void | |
319 | __morestack_fail (const char *msg, size_t len, int err) | |
320 | { | |
321 | char buf[24]; | |
322 | static const char nl[] = "\n"; | |
323 | struct iovec iov[3]; | |
324 | union { char *p; const char *cp; } const_cast; | |
325 | ||
326 | const_cast.cp = msg; | |
327 | iov[0].iov_base = const_cast.p; | |
328 | iov[0].iov_len = len; | |
329 | /* We can't call strerror, because it may try to translate the error | |
330 | message, and that would use too much stack space. */ | |
331 | iov[1].iov_base = print_int (err, buf, sizeof buf, &iov[1].iov_len); | |
332 | const_cast.cp = &nl[0]; | |
333 | iov[2].iov_base = const_cast.p; | |
334 | iov[2].iov_len = sizeof nl - 1; | |
335 | /* FIXME: On systems without writev we need to issue three write | |
336 | calls, or punt on printing errno. For now this is irrelevant | |
337 | since stack splitting only works on GNU/Linux anyhow. */ | |
338 | writev (2, iov, 3); | |
339 | abort (); | |
340 | } | |
341 | ||
342 | /* Allocate a new stack segment. FRAME_SIZE is the required frame | |
343 | size. */ | |
344 | ||
345 | static struct stack_segment * | |
346 | allocate_segment (size_t frame_size) | |
347 | { | |
7458026b ILT |
348 | unsigned int pagesize; |
349 | unsigned int overhead; | |
350 | unsigned int allocate; | |
351 | void *space; | |
352 | struct stack_segment *pss; | |
353 | ||
354 | pagesize = static_pagesize; | |
7458026b ILT |
355 | overhead = sizeof (struct stack_segment); |
356 | ||
357 | allocate = pagesize; | |
358 | if (allocate < MINSIGSTKSZ) | |
359 | allocate = ((MINSIGSTKSZ + overhead + pagesize - 1) | |
360 | & ~ (pagesize - 1)); | |
361 | if (allocate < frame_size) | |
362 | allocate = ((frame_size + overhead + pagesize - 1) | |
363 | & ~ (pagesize - 1)); | |
364 | ||
365 | if (use_guard_page) | |
366 | allocate += pagesize; | |
367 | ||
368 | /* FIXME: If this binary requires an executable stack, then we need | |
369 | to set PROT_EXEC. Unfortunately figuring that out is complicated | |
370 | and target dependent. We would need to use dl_iterate_phdr to | |
371 | see if there is any object which does not have a PT_GNU_STACK | |
372 | phdr, though only for architectures which use that mechanism. */ | |
373 | space = mmap (NULL, allocate, PROT_READ | PROT_WRITE, | |
374 | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); | |
375 | if (space == MAP_FAILED) | |
376 | { | |
377 | static const char msg[] = | |
378 | "unable to allocate additional stack space: errno "; | |
379 | __morestack_fail (msg, sizeof msg - 1, errno); | |
380 | } | |
381 | ||
382 | if (use_guard_page) | |
383 | { | |
384 | void *guard; | |
385 | ||
53d68b9f | 386 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
387 | guard = space; |
388 | space = (char *) space + pagesize; | |
389 | #else | |
390 | guard = space + allocate - pagesize; | |
391 | #endif | |
392 | ||
393 | mprotect (guard, pagesize, PROT_NONE); | |
394 | allocate -= pagesize; | |
395 | } | |
396 | ||
397 | pss = (struct stack_segment *) space; | |
398 | ||
e14304ef | 399 | pss->prev = NULL; |
7458026b ILT |
400 | pss->next = NULL; |
401 | pss->size = allocate - overhead; | |
402 | pss->dynamic_allocation = NULL; | |
403 | pss->free_dynamic_allocation = NULL; | |
404 | pss->extra = NULL; | |
405 | ||
7458026b ILT |
406 | return pss; |
407 | } | |
408 | ||
409 | /* Free a list of dynamic blocks. */ | |
410 | ||
411 | static void | |
412 | free_dynamic_blocks (struct dynamic_allocation_blocks *p) | |
413 | { | |
414 | while (p != NULL) | |
415 | { | |
416 | struct dynamic_allocation_blocks *next; | |
417 | ||
418 | next = p->next; | |
419 | free (p->block); | |
420 | free (p); | |
421 | p = next; | |
422 | } | |
423 | } | |
424 | ||
425 | /* Merge two lists of dynamic blocks. */ | |
426 | ||
427 | static struct dynamic_allocation_blocks * | |
428 | merge_dynamic_blocks (struct dynamic_allocation_blocks *a, | |
429 | struct dynamic_allocation_blocks *b) | |
430 | { | |
431 | struct dynamic_allocation_blocks **pp; | |
432 | ||
433 | if (a == NULL) | |
434 | return b; | |
435 | if (b == NULL) | |
436 | return a; | |
437 | for (pp = &a->next; *pp != NULL; pp = &(*pp)->next) | |
438 | ; | |
439 | *pp = b; | |
440 | return a; | |
441 | } | |
442 | ||
443 | /* Release stack segments. If FREE_DYNAMIC is non-zero, we also free | |
444 | any dynamic blocks. Otherwise we return them. */ | |
445 | ||
446 | struct dynamic_allocation_blocks * | |
447 | __morestack_release_segments (struct stack_segment **pp, int free_dynamic) | |
448 | { | |
449 | struct dynamic_allocation_blocks *ret; | |
450 | struct stack_segment *pss; | |
451 | ||
452 | ret = NULL; | |
453 | pss = *pp; | |
454 | while (pss != NULL) | |
455 | { | |
456 | struct stack_segment *next; | |
457 | unsigned int allocate; | |
458 | ||
459 | next = pss->next; | |
460 | ||
461 | if (pss->dynamic_allocation != NULL | |
462 | || pss->free_dynamic_allocation != NULL) | |
463 | { | |
464 | if (free_dynamic) | |
465 | { | |
466 | free_dynamic_blocks (pss->dynamic_allocation); | |
467 | free_dynamic_blocks (pss->free_dynamic_allocation); | |
468 | } | |
469 | else | |
470 | { | |
471 | ret = merge_dynamic_blocks (pss->dynamic_allocation, ret); | |
472 | ret = merge_dynamic_blocks (pss->free_dynamic_allocation, ret); | |
473 | } | |
474 | } | |
475 | ||
476 | allocate = pss->size + sizeof (struct stack_segment); | |
477 | if (munmap (pss, allocate) < 0) | |
478 | { | |
479 | static const char msg[] = "munmap of stack space failed: errno "; | |
480 | __morestack_fail (msg, sizeof msg - 1, errno); | |
481 | } | |
482 | ||
483 | pss = next; | |
484 | } | |
485 | *pp = NULL; | |
486 | ||
487 | return ret; | |
488 | } | |
489 | ||
490 | /* This function is called by a processor specific function to set the | |
491 | initial stack pointer for a thread. The operating system will | |
492 | always create a stack for a thread. Here we record a stack pointer | |
493 | near the base of that stack. The size argument lets the processor | |
494 | specific code estimate how much stack space is available on this | |
495 | initial stack. */ | |
496 | ||
497 | void | |
498 | __generic_morestack_set_initial_sp (void *sp, size_t len) | |
499 | { | |
500 | /* The stack pointer most likely starts on a page boundary. Adjust | |
501 | to the nearest 512 byte boundary. It's not essential that we be | |
502 | precise here; getting it wrong will just leave some stack space | |
503 | unused. */ | |
53d68b9f | 504 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
505 | sp = (void *) ((((__UINTPTR_TYPE__) sp + 511U) / 512U) * 512U); |
506 | #else | |
507 | sp = (void *) ((((__UINTPTR_TYPE__) sp - 511U) / 512U) * 512U); | |
508 | #endif | |
509 | ||
510 | __morestack_initial_sp.sp = sp; | |
511 | __morestack_initial_sp.len = len; | |
512 | sigemptyset (&__morestack_initial_sp.mask); | |
513 | ||
514 | sigfillset (&__morestack_fullmask); | |
d80c632e | 515 | #if defined(__GLIBC__) && defined(__linux__) |
a13780a6 | 516 | /* In glibc, the first two real time signals are used by the NPTL |
7458026b ILT |
517 | threading library. By taking them out of the set of signals, we |
518 | avoiding copying the signal mask in pthread_sigmask. More | |
519 | importantly, pthread_sigmask uses less stack space on x86_64. */ | |
520 | sigdelset (&__morestack_fullmask, __SIGRTMIN); | |
521 | sigdelset (&__morestack_fullmask, __SIGRTMIN + 1); | |
522 | #endif | |
523 | } | |
524 | ||
525 | /* This function is called by a processor specific function which is | |
526 | run in the prologue when more stack is needed. The processor | |
527 | specific function handles the details of saving registers and | |
528 | frobbing the actual stack pointer. This function is responsible | |
529 | for allocating a new stack segment and for copying a parameter | |
530 | block from the old stack to the new one. On function entry | |
531 | *PFRAME_SIZE is the size of the required stack frame--the returned | |
532 | stack must be at least this large. On function exit *PFRAME_SIZE | |
533 | is the amount of space remaining on the allocated stack. OLD_STACK | |
534 | points at the parameters the old stack (really the current one | |
535 | while this function is running). OLD_STACK is saved so that it can | |
536 | be returned by a later call to __generic_releasestack. PARAM_SIZE | |
537 | is the size in bytes of parameters to copy to the new stack. This | |
538 | function returns a pointer to the new stack segment, pointing to | |
539 | the memory after the parameters have been copied. The returned | |
540 | value minus the returned *PFRAME_SIZE (or plus if the stack grows | |
541 | upward) is the first address on the stack which should not be used. | |
542 | ||
543 | This function is running on the old stack and has only a limited | |
544 | amount of stack space available. */ | |
545 | ||
546 | void * | |
547 | __generic_morestack (size_t *pframe_size, void *old_stack, size_t param_size) | |
548 | { | |
549 | size_t frame_size = *pframe_size; | |
550 | struct stack_segment *current; | |
551 | struct stack_segment **pp; | |
552 | struct dynamic_allocation_blocks *dynamic; | |
553 | char *from; | |
554 | char *to; | |
555 | void *ret; | |
556 | size_t i; | |
e808687a | 557 | size_t aligned; |
7458026b ILT |
558 | |
559 | current = __morestack_current_segment; | |
560 | ||
561 | pp = current != NULL ? ¤t->next : &__morestack_segments; | |
562 | if (*pp != NULL && (*pp)->size < frame_size) | |
563 | dynamic = __morestack_release_segments (pp, 0); | |
564 | else | |
565 | dynamic = NULL; | |
566 | current = *pp; | |
567 | ||
568 | if (current == NULL) | |
e14304ef ILT |
569 | { |
570 | current = allocate_segment (frame_size + param_size); | |
571 | current->prev = __morestack_current_segment; | |
572 | *pp = current; | |
573 | } | |
7458026b ILT |
574 | |
575 | current->old_stack = old_stack; | |
576 | ||
577 | __morestack_current_segment = current; | |
578 | ||
579 | if (dynamic != NULL) | |
580 | { | |
581 | /* Move the free blocks onto our list. We don't want to call | |
582 | free here, as we are short on stack space. */ | |
583 | current->free_dynamic_allocation = | |
584 | merge_dynamic_blocks (dynamic, current->free_dynamic_allocation); | |
585 | } | |
586 | ||
587 | *pframe_size = current->size - param_size; | |
588 | ||
e808687a ILT |
589 | /* Align the returned stack to a 32-byte boundary. */ |
590 | aligned = (param_size + 31) & ~ (size_t) 31; | |
591 | ||
53d68b9f | 592 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
593 | { |
594 | char *bottom = (char *) (current + 1) + current->size; | |
e808687a ILT |
595 | to = bottom - aligned; |
596 | ret = bottom - aligned; | |
7458026b ILT |
597 | } |
598 | #else | |
599 | to = current + 1; | |
e808687a ILT |
600 | to += aligned - param_size; |
601 | ret = (char *) (current + 1) + aligned; | |
7458026b ILT |
602 | #endif |
603 | ||
604 | /* We don't call memcpy to avoid worrying about the dynamic linker | |
605 | trying to resolve it. */ | |
606 | from = (char *) old_stack; | |
607 | for (i = 0; i < param_size; i++) | |
608 | *to++ = *from++; | |
609 | ||
610 | return ret; | |
611 | } | |
612 | ||
613 | /* This function is called by a processor specific function when it is | |
614 | ready to release a stack segment. We don't actually release the | |
615 | stack segment, we just move back to the previous one. The current | |
616 | stack segment will still be available if we need it in | |
617 | __generic_morestack. This returns a pointer to the new stack | |
618 | segment to use, which is the one saved by a previous call to | |
619 | __generic_morestack. The processor specific function is then | |
620 | responsible for actually updating the stack pointer. This sets | |
621 | *PAVAILABLE to the amount of stack space now available. */ | |
622 | ||
623 | void * | |
624 | __generic_releasestack (size_t *pavailable) | |
625 | { | |
626 | struct stack_segment *current; | |
627 | void *old_stack; | |
628 | ||
629 | current = __morestack_current_segment; | |
630 | old_stack = current->old_stack; | |
631 | current = current->prev; | |
632 | __morestack_current_segment = current; | |
633 | ||
634 | if (current != NULL) | |
635 | { | |
53d68b9f | 636 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
637 | *pavailable = (char *) old_stack - (char *) (current + 1); |
638 | #else | |
639 | *pavailable = (char *) (current + 1) + current->size - (char *) old_stack; | |
640 | #endif | |
641 | } | |
642 | else | |
643 | { | |
644 | size_t used; | |
645 | ||
646 | /* We have popped back to the original stack. */ | |
53d68b9f | 647 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
648 | if ((char *) old_stack >= (char *) __morestack_initial_sp.sp) |
649 | used = 0; | |
650 | else | |
651 | used = (char *) __morestack_initial_sp.sp - (char *) old_stack; | |
652 | #else | |
653 | if ((char *) old_stack <= (char *) __morestack_initial_sp.sp) | |
654 | used = 0; | |
655 | else | |
656 | used = (char *) old_stack - (char *) __morestack_initial_sp.sp; | |
657 | #endif | |
658 | ||
659 | if (used > __morestack_initial_sp.len) | |
660 | *pavailable = 0; | |
661 | else | |
662 | *pavailable = __morestack_initial_sp.len - used; | |
663 | } | |
664 | ||
665 | return old_stack; | |
666 | } | |
667 | ||
668 | /* Block signals while splitting the stack. This avoids trouble if we | |
669 | try to invoke a signal handler which itself wants to split the | |
670 | stack. */ | |
671 | ||
672 | extern int pthread_sigmask (int, const sigset_t *, sigset_t *) | |
673 | __attribute__ ((weak)); | |
674 | ||
675 | void | |
676 | __morestack_block_signals (void) | |
677 | { | |
e14304ef ILT |
678 | if (__morestack_initial_sp.dont_block_signals) |
679 | ; | |
680 | else if (pthread_sigmask) | |
7458026b ILT |
681 | pthread_sigmask (SIG_BLOCK, &__morestack_fullmask, |
682 | &__morestack_initial_sp.mask); | |
683 | else | |
684 | sigprocmask (SIG_BLOCK, &__morestack_fullmask, | |
685 | &__morestack_initial_sp.mask); | |
686 | } | |
687 | ||
688 | /* Unblock signals while splitting the stack. */ | |
689 | ||
690 | void | |
691 | __morestack_unblock_signals (void) | |
692 | { | |
e14304ef ILT |
693 | if (__morestack_initial_sp.dont_block_signals) |
694 | ; | |
695 | else if (pthread_sigmask) | |
7458026b ILT |
696 | pthread_sigmask (SIG_SETMASK, &__morestack_initial_sp.mask, NULL); |
697 | else | |
698 | sigprocmask (SIG_SETMASK, &__morestack_initial_sp.mask, NULL); | |
699 | } | |
700 | ||
701 | /* This function is called to allocate dynamic stack space, for alloca | |
702 | or a variably sized array. This is a regular function with | |
703 | sufficient stack space, so we just use malloc to allocate the | |
704 | space. We attach the allocated blocks to the current stack | |
705 | segment, so that they will eventually be reused or freed. */ | |
706 | ||
707 | void * | |
708 | __morestack_allocate_stack_space (size_t size) | |
709 | { | |
710 | struct stack_segment *seg, *current; | |
711 | struct dynamic_allocation_blocks *p; | |
712 | ||
713 | /* We have to block signals to avoid getting confused if we get | |
714 | interrupted by a signal whose handler itself uses alloca or a | |
715 | variably sized array. */ | |
716 | __morestack_block_signals (); | |
717 | ||
718 | /* Since we don't want to call free while we are low on stack space, | |
719 | we may have a list of already allocated blocks waiting to be | |
720 | freed. Release them all, unless we find one that is large | |
721 | enough. We don't look at every block to see if one is large | |
722 | enough, just the first one, because we aren't trying to build a | |
723 | memory allocator here, we're just trying to speed up common | |
724 | cases. */ | |
725 | ||
726 | current = __morestack_current_segment; | |
727 | p = NULL; | |
728 | for (seg = __morestack_segments; seg != NULL; seg = seg->next) | |
729 | { | |
730 | p = seg->free_dynamic_allocation; | |
731 | if (p != NULL) | |
732 | { | |
733 | if (p->size >= size) | |
734 | { | |
735 | seg->free_dynamic_allocation = p->next; | |
736 | break; | |
737 | } | |
738 | ||
739 | free_dynamic_blocks (p); | |
740 | seg->free_dynamic_allocation = NULL; | |
741 | p = NULL; | |
742 | } | |
743 | } | |
744 | ||
745 | if (p == NULL) | |
746 | { | |
747 | /* We need to allocate additional memory. */ | |
748 | p = malloc (sizeof (*p)); | |
749 | if (p == NULL) | |
750 | abort (); | |
751 | p->size = size; | |
752 | p->block = malloc (size); | |
753 | if (p->block == NULL) | |
754 | abort (); | |
755 | } | |
756 | ||
757 | /* If we are still on the initial stack, then we have a space leak. | |
758 | FIXME. */ | |
759 | if (current != NULL) | |
760 | { | |
761 | p->next = current->dynamic_allocation; | |
762 | current->dynamic_allocation = p; | |
763 | } | |
764 | ||
765 | __morestack_unblock_signals (); | |
766 | ||
767 | return p->block; | |
768 | } | |
769 | ||
770 | /* Find the stack segment for STACK and return the amount of space | |
771 | available. This is used when unwinding the stack because of an | |
772 | exception, in order to reset the stack guard correctly. */ | |
773 | ||
774 | size_t | |
775 | __generic_findstack (void *stack) | |
776 | { | |
777 | struct stack_segment *pss; | |
778 | size_t used; | |
779 | ||
780 | for (pss = __morestack_current_segment; pss != NULL; pss = pss->prev) | |
781 | { | |
782 | if ((char *) pss < (char *) stack | |
783 | && (char *) pss + pss->size > (char *) stack) | |
784 | { | |
785 | __morestack_current_segment = pss; | |
53d68b9f | 786 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
787 | return (char *) stack - (char *) (pss + 1); |
788 | #else | |
789 | return (char *) (pss + 1) + pss->size - (char *) stack; | |
790 | #endif | |
791 | } | |
792 | } | |
793 | ||
794 | /* We have popped back to the original stack. */ | |
e14304ef ILT |
795 | |
796 | if (__morestack_initial_sp.sp == NULL) | |
797 | return 0; | |
798 | ||
53d68b9f | 799 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
800 | if ((char *) stack >= (char *) __morestack_initial_sp.sp) |
801 | used = 0; | |
802 | else | |
803 | used = (char *) __morestack_initial_sp.sp - (char *) stack; | |
804 | #else | |
805 | if ((char *) stack <= (char *) __morestack_initial_sp.sp) | |
806 | used = 0; | |
807 | else | |
808 | used = (char *) stack - (char *) __morestack_initial_sp.sp; | |
809 | #endif | |
810 | ||
811 | if (used > __morestack_initial_sp.len) | |
812 | return 0; | |
813 | else | |
814 | return __morestack_initial_sp.len - used; | |
815 | } | |
816 | ||
817 | /* This function is called at program startup time to make sure that | |
818 | mmap, munmap, and getpagesize are resolved if linking dynamically. | |
819 | We want to resolve them while we have enough stack for them, rather | |
1f3fa525 TM |
820 | than calling into the dynamic linker while low on stack space. |
821 | Similarly, invoke getenv here to check for split-stack related control | |
822 | variables, since doing do as part of the __morestack path can result | |
823 | in unwanted use of SSE/AVX registers (see GCC PR 86213). */ | |
7458026b ILT |
824 | |
825 | void | |
826 | __morestack_load_mmap (void) | |
827 | { | |
828 | /* Call with bogus values to run faster. We don't care if the call | |
829 | fails. Pass __MORESTACK_CURRENT_SEGMENT to make sure that any | |
830 | TLS accessor function is resolved. */ | |
831 | mmap (__morestack_current_segment, 0, PROT_READ, MAP_ANONYMOUS, -1, 0); | |
832 | mprotect (NULL, 0, 0); | |
1f3fa525 TM |
833 | munmap (0, static_pagesize); |
834 | ||
835 | /* Initialize these values here, so as to avoid dynamic linker | |
836 | activity as part of a __morestack call. */ | |
837 | static_pagesize = getpagesize(); | |
838 | use_guard_page = getenv ("SPLIT_STACK_GUARD") != 0; | |
7458026b ILT |
839 | } |
840 | ||
841 | /* This function may be used to iterate over the stack segments. | |
842 | This can be called like this. | |
843 | void *next_segment = NULL; | |
844 | void *next_sp = NULL; | |
845 | void *initial_sp = NULL; | |
846 | void *stack; | |
847 | size_t stack_size; | |
848 | while ((stack = __splitstack_find (next_segment, next_sp, &stack_size, | |
849 | &next_segment, &next_sp, | |
850 | &initial_sp)) != NULL) | |
851 | { | |
852 | // Stack segment starts at stack and is stack_size bytes long. | |
853 | } | |
854 | ||
855 | There is no way to iterate over the stack segments of a different | |
856 | thread. However, what is permitted is for one thread to call this | |
857 | with the first two values NULL, to pass next_segment, next_sp, and | |
858 | initial_sp to a different thread, and then to suspend one way or | |
859 | another. A different thread may run the subsequent | |
860 | __morestack_find iterations. Of course, this will only work if the | |
861 | first thread is suspended during the __morestack_find iterations. | |
862 | If not, the second thread will be looking at the stack while it is | |
863 | changing, and anything could happen. | |
864 | ||
865 | FIXME: This should be declared in some header file, but where? */ | |
866 | ||
867 | void * | |
868 | __splitstack_find (void *segment_arg, void *sp, size_t *len, | |
869 | void **next_segment, void **next_sp, | |
870 | void **initial_sp) | |
871 | { | |
872 | struct stack_segment *segment; | |
873 | void *ret; | |
874 | char *nsp; | |
875 | ||
e14304ef | 876 | if (segment_arg == (void *) (uintptr_type) 1) |
7458026b ILT |
877 | { |
878 | char *isp = (char *) *initial_sp; | |
879 | ||
e14304ef ILT |
880 | if (isp == NULL) |
881 | return NULL; | |
882 | ||
883 | *next_segment = (void *) (uintptr_type) 2; | |
7458026b | 884 | *next_sp = NULL; |
53d68b9f | 885 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
886 | if ((char *) sp >= isp) |
887 | return NULL; | |
888 | *len = (char *) isp - (char *) sp; | |
889 | return sp; | |
890 | #else | |
891 | if ((char *) sp <= (char *) isp) | |
892 | return NULL; | |
893 | *len = (char *) sp - (char *) isp; | |
894 | return (void *) isp; | |
895 | #endif | |
896 | } | |
e14304ef | 897 | else if (segment_arg == (void *) (uintptr_type) 2) |
7458026b ILT |
898 | return NULL; |
899 | else if (segment_arg != NULL) | |
900 | segment = (struct stack_segment *) segment_arg; | |
901 | else | |
902 | { | |
903 | *initial_sp = __morestack_initial_sp.sp; | |
904 | segment = __morestack_current_segment; | |
905 | sp = (void *) &segment; | |
906 | while (1) | |
907 | { | |
908 | if (segment == NULL) | |
e14304ef ILT |
909 | return __splitstack_find ((void *) (uintptr_type) 1, sp, len, |
910 | next_segment, next_sp, initial_sp); | |
7458026b ILT |
911 | if ((char *) sp >= (char *) (segment + 1) |
912 | && (char *) sp <= (char *) (segment + 1) + segment->size) | |
913 | break; | |
914 | segment = segment->prev; | |
915 | } | |
916 | } | |
917 | ||
918 | if (segment->prev == NULL) | |
e14304ef | 919 | *next_segment = (void *) (uintptr_type) 1; |
7458026b ILT |
920 | else |
921 | *next_segment = segment->prev; | |
922 | ||
923 | /* The old_stack value is the address of the function parameters of | |
924 | the function which called __morestack. So if f1 called f2 which | |
925 | called __morestack, the stack looks like this: | |
926 | ||
927 | parameters <- old_stack | |
928 | return in f1 | |
929 | return in f2 | |
457186f6 | 930 | registers pushed by __morestack |
7458026b | 931 | |
457186f6 ILT |
932 | The registers pushed by __morestack may not be visible on any |
933 | other stack, if we are being called by a signal handler | |
934 | immediately after the call to __morestack_unblock_signals. We | |
935 | want to adjust our return value to include those registers. This | |
936 | is target dependent. */ | |
7458026b ILT |
937 | |
938 | nsp = (char *) segment->old_stack; | |
457186f6 | 939 | |
a01207c4 ILT |
940 | if (nsp == NULL) |
941 | { | |
942 | /* We've reached the top of the stack. */ | |
943 | *next_segment = (void *) (uintptr_type) 2; | |
944 | } | |
945 | else | |
946 | { | |
457186f6 | 947 | #if defined (__x86_64__) |
a01207c4 | 948 | nsp -= 12 * sizeof (void *); |
457186f6 | 949 | #elif defined (__i386__) |
a01207c4 | 950 | nsp -= 6 * sizeof (void *); |
0f0fd745 | 951 | #elif defined __powerpc64__ |
4cb4721f MK |
952 | #elif defined __s390x__ |
953 | nsp -= 2 * 160; | |
954 | #elif defined __s390__ | |
955 | nsp -= 2 * 96; | |
7458026b | 956 | #else |
457186f6 | 957 | #error "unrecognized target" |
7458026b | 958 | #endif |
457186f6 | 959 | |
a01207c4 ILT |
960 | *next_sp = (void *) nsp; |
961 | } | |
7458026b | 962 | |
53d68b9f | 963 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
7458026b ILT |
964 | *len = (char *) (segment + 1) + segment->size - (char *) sp; |
965 | ret = (void *) sp; | |
966 | #else | |
967 | *len = (char *) sp - (char *) (segment + 1); | |
968 | ret = (void *) (segment + 1); | |
969 | #endif | |
970 | ||
971 | return ret; | |
972 | } | |
973 | ||
e14304ef ILT |
974 | /* Tell the split stack code whether it has to block signals while |
975 | manipulating the stack. This is for programs in which some threads | |
976 | block all signals. If a thread already blocks signals, there is no | |
977 | need for the split stack code to block them as well. If NEW is not | |
978 | NULL, then if *NEW is non-zero signals will be blocked while | |
979 | splitting the stack, otherwise they will not. If OLD is not NULL, | |
980 | *OLD will be set to the old value. */ | |
981 | ||
982 | void | |
983 | __splitstack_block_signals (int *new, int *old) | |
984 | { | |
985 | if (old != NULL) | |
986 | *old = __morestack_initial_sp.dont_block_signals ? 0 : 1; | |
987 | if (new != NULL) | |
988 | __morestack_initial_sp.dont_block_signals = *new ? 0 : 1; | |
989 | } | |
990 | ||
991 | /* The offsets into the arrays used by __splitstack_getcontext and | |
992 | __splitstack_setcontext. */ | |
993 | ||
994 | enum __splitstack_context_offsets | |
995 | { | |
996 | MORESTACK_SEGMENTS = 0, | |
997 | CURRENT_SEGMENT = 1, | |
998 | CURRENT_STACK = 2, | |
999 | STACK_GUARD = 3, | |
1000 | INITIAL_SP = 4, | |
1001 | INITIAL_SP_LEN = 5, | |
1002 | BLOCK_SIGNALS = 6, | |
1003 | ||
1004 | NUMBER_OFFSETS = 10 | |
1005 | }; | |
1006 | ||
1007 | /* Get the current split stack context. This may be used for | |
1008 | coroutine switching, similar to getcontext. The argument should | |
1009 | have at least 10 void *pointers for extensibility, although we | |
1010 | don't currently use all of them. This would normally be called | |
1011 | immediately before a call to getcontext or swapcontext or | |
1012 | setjmp. */ | |
1013 | ||
1014 | void | |
1015 | __splitstack_getcontext (void *context[NUMBER_OFFSETS]) | |
1016 | { | |
1017 | memset (context, 0, NUMBER_OFFSETS * sizeof (void *)); | |
1018 | context[MORESTACK_SEGMENTS] = (void *) __morestack_segments; | |
1019 | context[CURRENT_SEGMENT] = (void *) __morestack_current_segment; | |
1020 | context[CURRENT_STACK] = (void *) &context; | |
1021 | context[STACK_GUARD] = __morestack_get_guard (); | |
1022 | context[INITIAL_SP] = (void *) __morestack_initial_sp.sp; | |
1023 | context[INITIAL_SP_LEN] = (void *) (uintptr_type) __morestack_initial_sp.len; | |
1024 | context[BLOCK_SIGNALS] = (void *) __morestack_initial_sp.dont_block_signals; | |
1025 | } | |
1026 | ||
1027 | /* Set the current split stack context. The argument should be a | |
1028 | context previously passed to __splitstack_getcontext. This would | |
1029 | normally be called immediately after a call to getcontext or | |
1030 | swapcontext or setjmp if something jumped to it. */ | |
1031 | ||
1032 | void | |
1033 | __splitstack_setcontext (void *context[NUMBER_OFFSETS]) | |
1034 | { | |
1035 | __morestack_segments = (struct stack_segment *) context[MORESTACK_SEGMENTS]; | |
1036 | __morestack_current_segment = | |
1037 | (struct stack_segment *) context[CURRENT_SEGMENT]; | |
1038 | __morestack_set_guard (context[STACK_GUARD]); | |
1039 | __morestack_initial_sp.sp = context[INITIAL_SP]; | |
1040 | __morestack_initial_sp.len = (size_t) context[INITIAL_SP_LEN]; | |
1041 | __morestack_initial_sp.dont_block_signals = | |
1042 | (uintptr_type) context[BLOCK_SIGNALS]; | |
1043 | } | |
1044 | ||
1045 | /* Create a new split stack context. This will allocate a new stack | |
1046 | segment which may be used by a coroutine. STACK_SIZE is the | |
1047 | minimum size of the new stack. The caller is responsible for | |
1048 | actually setting the stack pointer. This would normally be called | |
1049 | before a call to makecontext, and the returned stack pointer and | |
1050 | size would be used to set the uc_stack field. A function called | |
1051 | via makecontext on a stack created by __splitstack_makecontext may | |
1052 | not return. Note that the returned pointer points to the lowest | |
1053 | address in the stack space, and thus may not be the value to which | |
1054 | to set the stack pointer. */ | |
1055 | ||
1056 | void * | |
1057 | __splitstack_makecontext (size_t stack_size, void *context[NUMBER_OFFSETS], | |
1058 | size_t *size) | |
1059 | { | |
1060 | struct stack_segment *segment; | |
1061 | void *initial_sp; | |
1062 | ||
1063 | memset (context, 0, NUMBER_OFFSETS * sizeof (void *)); | |
1064 | segment = allocate_segment (stack_size); | |
1065 | context[MORESTACK_SEGMENTS] = segment; | |
1066 | context[CURRENT_SEGMENT] = segment; | |
53d68b9f | 1067 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
e14304ef ILT |
1068 | initial_sp = (void *) ((char *) (segment + 1) + segment->size); |
1069 | #else | |
1070 | initial_sp = (void *) (segment + 1); | |
1071 | #endif | |
1072 | context[STACK_GUARD] = __morestack_make_guard (initial_sp, segment->size); | |
1073 | context[INITIAL_SP] = NULL; | |
1074 | context[INITIAL_SP_LEN] = 0; | |
1075 | *size = segment->size; | |
1076 | return (void *) (segment + 1); | |
1077 | } | |
1078 | ||
a01207c4 ILT |
1079 | /* Given an existing split stack context, reset it back to the start |
1080 | of the stack. Return the stack pointer and size, appropriate for | |
1081 | use with makecontext. This may be used if a coroutine exits, in | |
1082 | order to reuse the stack segments for a new coroutine. */ | |
1083 | ||
1084 | void * | |
1085 | __splitstack_resetcontext (void *context[10], size_t *size) | |
1086 | { | |
1087 | struct stack_segment *segment; | |
1088 | void *initial_sp; | |
1089 | size_t initial_size; | |
1090 | void *ret; | |
1091 | ||
1092 | /* Reset the context assuming that MORESTACK_SEGMENTS, INITIAL_SP | |
1093 | and INITIAL_SP_LEN are correct. */ | |
1094 | ||
1095 | segment = context[MORESTACK_SEGMENTS]; | |
1096 | context[CURRENT_SEGMENT] = segment; | |
1097 | context[CURRENT_STACK] = NULL; | |
1098 | if (segment == NULL) | |
1099 | { | |
1100 | initial_sp = context[INITIAL_SP]; | |
1101 | initial_size = (uintptr_type) context[INITIAL_SP_LEN]; | |
1102 | ret = initial_sp; | |
53d68b9f | 1103 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
a01207c4 ILT |
1104 | ret = (void *) ((char *) ret - initial_size); |
1105 | #endif | |
1106 | } | |
1107 | else | |
1108 | { | |
53d68b9f | 1109 | #ifdef __LIBGCC_STACK_GROWS_DOWNWARD__ |
a01207c4 ILT |
1110 | initial_sp = (void *) ((char *) (segment + 1) + segment->size); |
1111 | #else | |
1112 | initial_sp = (void *) (segment + 1); | |
1113 | #endif | |
1114 | initial_size = segment->size; | |
1115 | ret = (void *) (segment + 1); | |
1116 | } | |
1117 | context[STACK_GUARD] = __morestack_make_guard (initial_sp, initial_size); | |
1118 | context[BLOCK_SIGNALS] = NULL; | |
1119 | *size = initial_size; | |
1120 | return ret; | |
1121 | } | |
1122 | ||
1123 | /* Release all the memory associated with a splitstack context. This | |
1124 | may be used if a coroutine exits and the associated stack should be | |
1125 | freed. */ | |
1126 | ||
1127 | void | |
1128 | __splitstack_releasecontext (void *context[10]) | |
1129 | { | |
e9e053eb ILT |
1130 | __morestack_release_segments (((struct stack_segment **) |
1131 | &context[MORESTACK_SEGMENTS]), | |
1132 | 1); | |
a01207c4 ILT |
1133 | } |
1134 | ||
e14304ef ILT |
1135 | /* Like __splitstack_block_signals, but operating on CONTEXT, rather |
1136 | than on the current state. */ | |
1137 | ||
1138 | void | |
1139 | __splitstack_block_signals_context (void *context[NUMBER_OFFSETS], int *new, | |
1140 | int *old) | |
1141 | { | |
1142 | if (old != NULL) | |
1143 | *old = ((uintptr_type) context[BLOCK_SIGNALS]) != 0 ? 0 : 1; | |
1144 | if (new != NULL) | |
1145 | context[BLOCK_SIGNALS] = (void *) (uintptr_type) (*new ? 0 : 1); | |
1146 | } | |
1147 | ||
1148 | /* Find the stack segments associated with a split stack context. | |
1149 | This will return the address of the first stack segment and set | |
1150 | *STACK_SIZE to its size. It will set next_segment, next_sp, and | |
1151 | initial_sp which may be passed to __splitstack_find to find the | |
1152 | remaining segments. */ | |
1153 | ||
1154 | void * | |
1155 | __splitstack_find_context (void *context[NUMBER_OFFSETS], size_t *stack_size, | |
1156 | void **next_segment, void **next_sp, | |
1157 | void **initial_sp) | |
1158 | { | |
1159 | void *sp; | |
1160 | struct stack_segment *segment; | |
1161 | ||
1162 | *initial_sp = context[INITIAL_SP]; | |
1163 | ||
1164 | sp = context[CURRENT_STACK]; | |
1165 | if (sp == NULL) | |
1166 | { | |
1167 | /* Most likely this context was created but was never used. The | |
1168 | value 2 is a code used by __splitstack_find to mean that we | |
1169 | have reached the end of the list of stacks. */ | |
1170 | *next_segment = (void *) (uintptr_type) 2; | |
1171 | *next_sp = NULL; | |
1172 | *initial_sp = NULL; | |
1173 | return NULL; | |
1174 | } | |
1175 | ||
1176 | segment = context[CURRENT_SEGMENT]; | |
1177 | if (segment == NULL) | |
1178 | { | |
1179 | /* Most likely this context was saved by a thread which was not | |
1180 | created using __splistack_makecontext and which has never | |
1181 | split the stack. The value 1 is a code used by | |
1182 | __splitstack_find to look at the initial stack. */ | |
1183 | segment = (struct stack_segment *) (uintptr_type) 1; | |
1184 | } | |
1185 | ||
1186 | return __splitstack_find (segment, sp, stack_size, next_segment, next_sp, | |
1187 | initial_sp); | |
1188 | } | |
1189 | ||
7458026b | 1190 | #endif /* !defined (inhibit_libc) */ |
0f0fd745 | 1191 | #endif /* not powerpc 32-bit */ |