1 /*
2  * Copyright (c) 2020 Intel Corporation
3  *
4  * SPDX-License-Identifier: Apache-2.0
5  */
6 
7 /**
8  * @file
9  *
10  * @brief Macros for declaring thread stacks
11  */
12 
13 /**
14  * @brief Thread Stack APIs
15  * @ingroup kernel_apis
16  * @defgroup thread_stack_api Thread Stack APIs
17  * @{
18  * @}
19  */
20 
21 #ifndef ZEPHYR_INCLUDE_KERNEL_THREAD_STACK_H
22 #define ZEPHYR_INCLUDE_KERNEL_THREAD_STACK_H
23 
24 #if !defined(_ASMLANGUAGE)
25 #include <zephyr/arch/cpu.h>
26 #include <zephyr/sys/util.h>
27 
28 #ifdef __cplusplus
29 extern "C" {
30 #endif
31 
32 /* Using typedef deliberately here, this is quite intended to be an opaque
33  * type.
34  *
35  * The purpose of this data type is to clearly distinguish between the
36  * declared symbol for a stack (of type k_thread_stack_t) and the underlying
37  * buffer which composes the stack data actually used by the underlying
38  * thread; they cannot be used interchangeably as some arches precede the
39  * stack buffer region with guard areas that trigger a MPU or MMU fault
40  * if written to.
41  *
42  * APIs that want to work with the buffer inside should continue to use
43  * char *.
44  *
45  * Stacks should always be created with K_THREAD_STACK_DEFINE().
46  */
47 struct __packed z_thread_stack_element {
48 	char data;
49 };
50 
51 /**
52  * @typedef k_thread_stack_t
53  * @brief Typedef of struct z_thread_stack_element
54  *
55  * @see z_thread_stack_element
56  */
57 
58 
59 /**
60  * @brief Properly align a CPU stack pointer value
61  *
62  * Take the provided value and round it down such that the value is aligned
63  * to the CPU and ABI requirements. This is not used for any memory protection
64  * hardware requirements.
65  *
66  * @param ptr Proposed stack pointer address
67  * @return Properly aligned stack pointer address
68  */
z_stack_ptr_align(char * ptr)69 static inline char *z_stack_ptr_align(char *ptr)
70 {
71 	return (char *)ROUND_DOWN(ptr, ARCH_STACK_PTR_ALIGN);
72 }
73 #define Z_STACK_PTR_ALIGN(ptr) ((uintptr_t)z_stack_ptr_align((char *)(ptr)))
74 
75 /**
76  * @brief Helper macro for getting a stack frame struct
77  *
78  * It is very common for architectures to define a struct which contains
79  * all the data members that are pre-populated in arch_new_thread().
80  *
81  * Given a type and an initial stack pointer, return a properly cast
82  * pointer to the frame struct.
83  *
84  * @param type Type of the initial stack frame struct
85  * @param ptr Initial aligned stack pointer value
86  * @return Pointer to stack frame struct within the stack buffer
87  */
88 #define Z_STACK_PTR_TO_FRAME(type, ptr) \
89 	(type *)((ptr) - sizeof(type))
90 
91 #ifdef ARCH_KERNEL_STACK_RESERVED
92 #define K_KERNEL_STACK_RESERVED	((size_t)ARCH_KERNEL_STACK_RESERVED)
93 #else
94 #define K_KERNEL_STACK_RESERVED	((size_t)0)
95 #endif /* ARCH_KERNEL_STACK_RESERVED */
96 
97 #define Z_KERNEL_STACK_SIZE_ADJUST(size) (ROUND_UP(size, \
98 						   ARCH_STACK_PTR_ALIGN) + \
99 					  K_KERNEL_STACK_RESERVED)
100 
101 #ifdef ARCH_KERNEL_STACK_OBJ_ALIGN
102 #define Z_KERNEL_STACK_OBJ_ALIGN	ARCH_KERNEL_STACK_OBJ_ALIGN
103 #else
104 #define Z_KERNEL_STACK_OBJ_ALIGN	ARCH_STACK_PTR_ALIGN
105 #endif /* ARCH_KERNEL_STACK_OBJ_ALIGN */
106 
107 #define K_KERNEL_STACK_LEN(size) \
108 	ROUND_UP(Z_KERNEL_STACK_SIZE_ADJUST(size), Z_KERNEL_STACK_OBJ_ALIGN)
109 
110 /**
111  * @addtogroup thread_stack_api
112  * @{
113  */
114 
115 /**
116  * @brief Declare a reference to a thread stack
117  *
118  * This macro declares the symbol of a thread stack defined elsewhere in the
119  * current scope.
120  *
121  * @param sym Thread stack symbol name
122  * @param size Size of the stack memory region
123  */
124 #define K_KERNEL_STACK_DECLARE(sym, size) \
125 	extern struct z_thread_stack_element \
126 		sym[K_KERNEL_STACK_LEN(size)]
127 
128 /**
129  * @brief Declare a reference to a thread stack array
130  *
131  * This macro declares the symbol of a thread stack array defined elsewhere in
132  * the current scope.
133  *
134  * @param sym Thread stack symbol name
135  * @param nmemb Number of stacks defined
136  * @param size Size of the stack memory region
137  */
138 #define K_KERNEL_STACK_ARRAY_DECLARE(sym, nmemb, size) \
139 	extern struct z_thread_stack_element \
140 		sym[nmemb][K_KERNEL_STACK_LEN(size)]
141 
142 /**
143  * @brief Declare a reference to a pinned thread stack array
144  *
145  * This macro declares the symbol of a pinned thread stack array defined
146  * elsewhere in the current scope.
147  *
148  * @param sym Thread stack symbol name
149  * @param nmemb Number of stacks defined
150  * @param size Size of the stack memory region
151  */
152 #define K_KERNEL_PINNED_STACK_ARRAY_DECLARE(sym, nmemb, size) \
153 	extern struct z_thread_stack_element \
154 		sym[nmemb][K_KERNEL_STACK_LEN(size)]
155 
156 /**
157  * @brief Define a toplevel kernel stack memory region in specified section
158  *
159  * This defines a region of memory for use as a thread stack in
160  * the specified linker section.
161  *
162  * It is legal to precede this definition with the 'static' keyword.
163  *
164  * It is NOT legal to take the sizeof(sym) and pass that to the stackSize
165  * parameter of k_thread_create(), it may not be the same as the
166  * 'size' parameter. Use K_KERNEL_STACK_SIZEOF() instead.
167  *
168  * The total amount of memory allocated may be increased to accommodate
169  * fixed-size stack overflow guards.
170  *
171  * @param sym Thread stack symbol name
172  * @param size Size of the stack memory region
173  * @param lsect Linker section for this stack
174  */
175 #define Z_KERNEL_STACK_DEFINE_IN(sym, size, lsect) \
176 	struct z_thread_stack_element lsect \
177 		__aligned(Z_KERNEL_STACK_OBJ_ALIGN) \
178 		sym[K_KERNEL_STACK_LEN(size)]
179 
180 /**
181  * @brief Define a toplevel array of kernel stack memory regions in specified section
182  *
183  * @param sym Kernel stack array symbol name
184  * @param nmemb Number of stacks to define
185  * @param size Size of the stack memory region
186  * @param lsect Linker section for this array of stacks
187  */
188 #define Z_KERNEL_STACK_ARRAY_DEFINE_IN(sym, nmemb, size, lsect) \
189 	struct z_thread_stack_element lsect \
190 		__aligned(Z_KERNEL_STACK_OBJ_ALIGN) \
191 		sym[nmemb][K_KERNEL_STACK_LEN(size)]
192 
193 /**
194  * @brief Define a toplevel kernel stack memory region
195  *
196  * This defines a region of memory for use as a thread stack, for threads
197  * that exclusively run in supervisor mode. This is also suitable for
198  * declaring special stacks for interrupt or exception handling.
199  *
200  * Stacks defined with this macro may not host user mode threads.
201  *
202  * It is legal to precede this definition with the 'static' keyword.
203  *
204  * It is NOT legal to take the sizeof(sym) and pass that to the stackSize
205  * parameter of k_thread_create(), it may not be the same as the
206  * 'size' parameter. Use K_KERNEL_STACK_SIZEOF() instead.
207  *
208  * The total amount of memory allocated may be increased to accommodate
209  * fixed-size stack overflow guards.
210  *
211  * @param sym Thread stack symbol name
212  * @param size Size of the stack memory region
213  */
214 #define K_KERNEL_STACK_DEFINE(sym, size) \
215 	Z_KERNEL_STACK_DEFINE_IN(sym, size, __kstackmem)
216 
217 /**
218  * @brief Define a toplevel kernel stack memory region in pinned section
219  *
220  * See K_KERNEL_STACK_DEFINE() for more information and constraints.
221  *
222  * This puts the stack into the pinned noinit linker section if
223  * CONFIG_LINKER_USE_PINNED_SECTION is enabled, or else it would
224  * put the stack into the same section as K_KERNEL_STACK_DEFINE().
225  *
226  * @param sym Thread stack symbol name
227  * @param size Size of the stack memory region
228  */
229 #if defined(CONFIG_LINKER_USE_PINNED_SECTION)
230 #define K_KERNEL_PINNED_STACK_DEFINE(sym, size) \
231 	Z_KERNEL_STACK_DEFINE_IN(sym, size, __pinned_noinit)
232 #else
233 #define K_KERNEL_PINNED_STACK_DEFINE(sym, size) \
234 	Z_KERNEL_STACK_DEFINE_IN(sym, size, __kstackmem)
235 #endif /* CONFIG_LINKER_USE_PINNED_SECTION */
236 
237 /**
238  * @brief Define a toplevel array of kernel stack memory regions
239  *
240  * Stacks defined with this macro may not host user mode threads.
241  *
242  * @param sym Kernel stack array symbol name
243  * @param nmemb Number of stacks to define
244  * @param size Size of the stack memory region
245  */
246 #define K_KERNEL_STACK_ARRAY_DEFINE(sym, nmemb, size) \
247 	Z_KERNEL_STACK_ARRAY_DEFINE_IN(sym, nmemb, size, __kstackmem)
248 
249 /**
250  * @brief Define a toplevel array of kernel stack memory regions in pinned section
251  *
252  * See K_KERNEL_STACK_ARRAY_DEFINE() for more information and constraints.
253  *
254  * This puts the stack into the pinned noinit linker section if
255  * CONFIG_LINKER_USE_PINNED_SECTION is enabled, or else it would
256  * put the stack into the same section as K_KERNEL_STACK_ARRAY_DEFINE().
257  *
258  * @param sym Kernel stack array symbol name
259  * @param nmemb Number of stacks to define
260  * @param size Size of the stack memory region
261  */
262 #if defined(CONFIG_LINKER_USE_PINNED_SECTION)
263 #define K_KERNEL_PINNED_STACK_ARRAY_DEFINE(sym, nmemb, size) \
264 	Z_KERNEL_STACK_ARRAY_DEFINE_IN(sym, nmemb, size, __pinned_noinit)
265 #else
266 #define K_KERNEL_PINNED_STACK_ARRAY_DEFINE(sym, nmemb, size) \
267 	Z_KERNEL_STACK_ARRAY_DEFINE_IN(sym, nmemb, size, __kstackmem)
268 #endif /* CONFIG_LINKER_USE_PINNED_SECTION */
269 
270 /**
271  * @brief Define an embedded stack memory region
272  *
273  * Used for kernel stacks embedded within other data structures.
274  *
275  * Stacks defined with this macro may not host user mode threads.
276  * @param sym Thread stack symbol name
277  * @param size Size of the stack memory region
278  */
279 #define K_KERNEL_STACK_MEMBER(sym, size) \
280 	Z_KERNEL_STACK_DEFINE_IN(sym, size,)
281 
282 #define K_KERNEL_STACK_SIZEOF(sym) (sizeof(sym) - K_KERNEL_STACK_RESERVED)
283 
284 /** @} */
285 
K_KERNEL_STACK_BUFFER(k_thread_stack_t * sym)286 static inline char *K_KERNEL_STACK_BUFFER(k_thread_stack_t *sym)
287 {
288 	return (char *)sym + K_KERNEL_STACK_RESERVED;
289 }
290 #ifndef CONFIG_USERSPACE
291 #define K_THREAD_STACK_RESERVED		K_KERNEL_STACK_RESERVED
292 #define K_THREAD_STACK_SIZEOF		K_KERNEL_STACK_SIZEOF
293 #define K_THREAD_STACK_LEN		K_KERNEL_STACK_LEN
294 #define K_THREAD_STACK_DEFINE		K_KERNEL_STACK_DEFINE
295 #define K_THREAD_STACK_ARRAY_DEFINE	K_KERNEL_STACK_ARRAY_DEFINE
296 #define K_THREAD_STACK_BUFFER		K_KERNEL_STACK_BUFFER
297 #define K_THREAD_STACK_DECLARE		K_KERNEL_STACK_DECLARE
298 #define K_THREAD_STACK_ARRAY_DECLARE	K_KERNEL_STACK_ARRAY_DECLARE
299 #define K_THREAD_PINNED_STACK_DEFINE	K_KERNEL_PINNED_STACK_DEFINE
300 #define K_THREAD_PINNED_STACK_ARRAY_DEFINE \
301 					K_KERNEL_PINNED_STACK_ARRAY_DEFINE
302 #else
303 /**
304  * @brief Indicate how much additional memory is reserved for stack objects
305  *
306  * Any given stack declaration may have additional memory in it for guard
307  * areas, supervisor mode stacks, or platform-specific data.  This macro
308  * indicates how much space is reserved for this.
309  *
310  * This value only indicates memory that is permanently reserved in the stack
311  * object. Memory that is "borrowed" from the thread's stack buffer is never
312  * accounted for here.
313  *
314  * Reserved memory is at the beginning of the stack object. The reserved area
315  * must be appropriately sized such that the stack buffer immediately following
316  * it is correctly aligned.
317  */
318 #ifdef ARCH_THREAD_STACK_RESERVED
319 #define K_THREAD_STACK_RESERVED		((size_t)(ARCH_THREAD_STACK_RESERVED))
320 #else
321 #define K_THREAD_STACK_RESERVED		((size_t)0U)
322 #endif /* ARCH_THREAD_STACK_RESERVED */
323 
324 /**
325  * @brief Properly align the lowest address of a stack object
326  *
327  * Return an alignment value for the lowest address of a stack object, taking
328  * into consideration all alignment constraints imposed by the CPU, ABI, and
329  * any memory management policies, including any alignment required by
330  * reserved platform data within the stack object. This will always be at least
331  * ARCH_STACK_PTR_ALIGN or an even multiple thereof.
332  *
333  * Depending on hardware, this is either a fixed value or a function of the
334  * provided size. The requested size is significant only if
335  * CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT is enabled.
336  *
337  * If CONFIG_USERSPACE is enabled, this determines the alignment of stacks
338  * which may be used by user mode threads, or threads running in supervisor
339  * mode which may later drop privileges to user mode.
340  *
341  * Arches define this with ARCH_THREAD_STACK_OBJ_ALIGN().
342  *
343  * If ARCH_THREAD_STACK_OBJ_ALIGN is not defined assume ARCH_STACK_PTR_ALIGN
344  * is appropriate.
345  *
346  * @param size Requested size of the stack buffer (which could be ignored)
347  * @return Alignment of the stack object
348  */
349 #if defined(ARCH_THREAD_STACK_OBJ_ALIGN)
350 #define Z_THREAD_STACK_OBJ_ALIGN(size)	\
351 	ARCH_THREAD_STACK_OBJ_ALIGN(Z_THREAD_STACK_SIZE_ADJUST(size))
352 #else
353 #define Z_THREAD_STACK_OBJ_ALIGN(size)	ARCH_STACK_PTR_ALIGN
354 #endif /* ARCH_THREAD_STACK_OBJ_ALIGN */
355 
356 /**
357  * @brief Round up a requested stack size to satisfy constraints
358  *
359  * Given a requested stack buffer size, return an adjusted size value for
360  * the entire stack object which takes into consideration:
361  *
362  * - Reserved memory for platform data
363  * - Alignment of stack buffer bounds to CPU/ABI constraints
364  * - Alignment of stack buffer bounds to satisfy memory management hardware
365  *   constraints such that a protection region can cover the stack buffer area
366  *
367  * If CONFIG_USERSPACE is enabled, this determines the size of stack objects
368  * which  may be used by user mode threads, or threads running in supervisor
369  * mode which may later drop privileges to user mode.
370  *
371  * Arches define this with ARCH_THREAD_STACK_SIZE_ADJUST().
372  *
373  * If ARCH_THREAD_STACK_SIZE_ADJUST is not defined, assume rounding up to
374  * ARCH_STACK_PTR_ALIGN is appropriate.
375  *
376  * Any memory reserved for platform data is also included in the total
377  * returned.
378  *
379  * @param size Requested size of the stack buffer
380  * @return Adjusted size of the stack object
381  */
382 #if defined(ARCH_THREAD_STACK_SIZE_ADJUST)
383 #define Z_THREAD_STACK_SIZE_ADJUST(size) \
384 	ARCH_THREAD_STACK_SIZE_ADJUST((size) + K_THREAD_STACK_RESERVED)
385 #else
386 #define Z_THREAD_STACK_SIZE_ADJUST(size) \
387 	(ROUND_UP((size), ARCH_STACK_PTR_ALIGN) + K_THREAD_STACK_RESERVED)
388 #endif /* ARCH_THREAD_STACK_SIZE_ADJUST */
389 
390 /**
391  * @addtogroup thread_stack_api
392  * @{
393  */
394 
395 /**
396  * @brief Declare a reference to a thread stack
397  *
398  * This macro declares the symbol of a thread stack defined elsewhere in the
399  * current scope.
400  *
401  * @param sym Thread stack symbol name
402  * @param size Size of the stack memory region
403  */
404 #define K_THREAD_STACK_DECLARE(sym, size) \
405 	extern struct z_thread_stack_element \
406 		sym[K_THREAD_STACK_LEN(size)]
407 
408 /**
409  * @brief Declare a reference to a thread stack array
410  *
411  * This macro declares the symbol of a thread stack array defined elsewhere in
412  * the current scope.
413  *
414  * @param sym Thread stack symbol name
415  * @param nmemb Number of stacks defined
416  * @param size Size of the stack memory region
417  */
418 #define K_THREAD_STACK_ARRAY_DECLARE(sym, nmemb, size) \
419 	extern struct z_thread_stack_element \
420 		sym[nmemb][K_THREAD_STACK_LEN(size)]
421 
422 /**
423  * @brief Return the size in bytes of a stack memory region
424  *
425  * Convenience macro for passing the desired stack size to k_thread_create()
426  * since the underlying implementation may actually create something larger
427  * (for instance a guard area).
428  *
429  * The value returned here is not guaranteed to match the 'size' parameter
430  * passed to K_THREAD_STACK_DEFINE and may be larger, but is always safe to
431  * pass to k_thread_create() for the associated stack object.
432  *
433  * @param sym Stack memory symbol
434  * @return Size of the stack buffer
435  */
436 #define K_THREAD_STACK_SIZEOF(sym)	(sizeof(sym) - K_THREAD_STACK_RESERVED)
437 
438 /**
439  * @brief Define a toplevel thread stack memory region in specified region
440  *
441  * This defines a region of memory suitable for use as a thread's stack
442  * in specified region.
443  *
444  * This is the generic, historical definition. Align to Z_THREAD_STACK_OBJ_ALIGN
445  * and put in 'noinit' section so that it isn't zeroed at boot
446  *
447  * The defined symbol will always be a k_thread_stack_t which can be passed to
448  * k_thread_create(), but should otherwise not be manipulated. If the buffer
449  * inside needs to be examined, examine thread->stack_info for the associated
450  * thread object to obtain the boundaries.
451  *
452  * It is legal to precede this definition with the 'static' keyword.
453  *
454  * It is NOT legal to take the sizeof(sym) and pass that to the stackSize
455  * parameter of k_thread_create(), it may not be the same as the
456  * 'size' parameter. Use K_THREAD_STACK_SIZEOF() instead.
457  *
458  * Some arches may round the size of the usable stack region up to satisfy
459  * alignment constraints. K_THREAD_STACK_SIZEOF() will return the aligned
460  * size.
461  *
462  * @param sym Thread stack symbol name
463  * @param size Size of the stack memory region
464  * @param lsect Linker section for this stack
465  */
466 #define Z_THREAD_STACK_DEFINE_IN(sym, size, lsect) \
467 	struct z_thread_stack_element lsect \
468 		__aligned(Z_THREAD_STACK_OBJ_ALIGN(size)) \
469 		sym[K_THREAD_STACK_LEN(size)]
470 
471 /**
472  * @brief Define a toplevel array of thread stack memory regions in specified region
473  *
474  * Create an array of equally sized stacks. See Z_THREAD_STACK_DEFINE_IN
475  * definition for additional details and constraints.
476  *
477  * This is the generic, historical definition. Align to Z_THREAD_STACK_OBJ_ALIGN
478  * and put in specified section so that it isn't zeroed at boot
479  *
480  * @param sym Thread stack symbol name
481  * @param nmemb Number of stacks to define
482  * @param size Size of the stack memory region
483  * @param lsect Linker section for this stack
484  */
485 #define Z_THREAD_STACK_ARRAY_DEFINE_IN(sym, nmemb, size, lsect) \
486 	struct z_thread_stack_element lsect \
487 		__aligned(Z_THREAD_STACK_OBJ_ALIGN(size)) \
488 		sym[nmemb][K_THREAD_STACK_LEN(size)]
489 
490 /**
491  * @brief Define a toplevel thread stack memory region
492  *
493  * This defines a region of memory suitable for use as a thread's stack.
494  *
495  * This is the generic, historical definition. Align to Z_THREAD_STACK_OBJ_ALIGN
496  * and put in 'noinit' section so that it isn't zeroed at boot
497  *
498  * The defined symbol will always be a k_thread_stack_t which can be passed to
499  * k_thread_create(), but should otherwise not be manipulated. If the buffer
500  * inside needs to be examined, examine thread->stack_info for the associated
501  * thread object to obtain the boundaries.
502  *
503  * It is legal to precede this definition with the 'static' keyword.
504  *
505  * It is NOT legal to take the sizeof(sym) and pass that to the stackSize
506  * parameter of k_thread_create(), it may not be the same as the
507  * 'size' parameter. Use K_THREAD_STACK_SIZEOF() instead.
508  *
509  * Some arches may round the size of the usable stack region up to satisfy
510  * alignment constraints. K_THREAD_STACK_SIZEOF() will return the aligned
511  * size.
512  *
513  * @param sym Thread stack symbol name
514  * @param size Size of the stack memory region
515  */
516 #define K_THREAD_STACK_DEFINE(sym, size) \
517 	Z_THREAD_STACK_DEFINE_IN(sym, size, __stackmem)
518 
519 /**
520  * @brief Define a toplevel thread stack memory region in pinned section
521  *
522  * This defines a region of memory suitable for use as a thread's stack.
523  *
524  * This is the generic, historical definition. Align to Z_THREAD_STACK_OBJ_ALIGN
525  * and put in 'noinit' section so that it isn't zeroed at boot
526  *
527  * The defined symbol will always be a k_thread_stack_t which can be passed to
528  * k_thread_create(), but should otherwise not be manipulated. If the buffer
529  * inside needs to be examined, examine thread->stack_info for the associated
530  * thread object to obtain the boundaries.
531  *
532  * It is legal to precede this definition with the 'static' keyword.
533  *
534  * It is NOT legal to take the sizeof(sym) and pass that to the stackSize
535  * parameter of k_thread_create(), it may not be the same as the
536  * 'size' parameter. Use K_THREAD_STACK_SIZEOF() instead.
537  *
538  * Some arches may round the size of the usable stack region up to satisfy
539  * alignment constraints. K_THREAD_STACK_SIZEOF() will return the aligned
540  * size.
541  *
542  * This puts the stack into the pinned noinit linker section if
543  * CONFIG_LINKER_USE_PINNED_SECTION is enabled, or else it would
544  * put the stack into the same section as K_THREAD_STACK_DEFINE().
545  *
546  * @param sym Thread stack symbol name
547  * @param size Size of the stack memory region
548  */
549 #if defined(CONFIG_LINKER_USE_PINNED_SECTION)
550 #define K_THREAD_PINNED_STACK_DEFINE(sym, size) \
551 	Z_THREAD_STACK_DEFINE_IN(sym, size, __pinned_noinit)
552 #else
553 #define K_THREAD_PINNED_STACK_DEFINE(sym, size) \
554 	K_THREAD_STACK_DEFINE(sym, size)
555 #endif /* CONFIG_LINKER_USE_PINNED_SECTION */
556 
557 /**
558  * @brief Calculate size of stacks to be allocated in a stack array
559  *
560  * This macro calculates the size to be allocated for the stacks
561  * inside a stack array. It accepts the indicated "size" as a parameter
562  * and if required, pads some extra bytes (e.g. for MPU scenarios). Refer
563  * K_THREAD_STACK_ARRAY_DEFINE definition to see how this is used.
564  * The returned size ensures each array member will be aligned to the
565  * required stack base alignment.
566  *
567  * @param size Size of the stack memory region
568  * @return Appropriate size for an array member
569  */
570 #define K_THREAD_STACK_LEN(size) \
571 	ROUND_UP(Z_THREAD_STACK_SIZE_ADJUST(size), \
572 		 Z_THREAD_STACK_OBJ_ALIGN(size))
573 
574 /**
575  * @brief Define a toplevel array of thread stack memory regions
576  *
577  * Create an array of equally sized stacks. See K_THREAD_STACK_DEFINE
578  * definition for additional details and constraints.
579  *
580  * This is the generic, historical definition. Align to Z_THREAD_STACK_OBJ_ALIGN
581  * and put in 'noinit' section so that it isn't zeroed at boot
582  *
583  * @param sym Thread stack symbol name
584  * @param nmemb Number of stacks to define
585  * @param size Size of the stack memory region
586  */
587 #define K_THREAD_STACK_ARRAY_DEFINE(sym, nmemb, size) \
588 	Z_THREAD_STACK_ARRAY_DEFINE_IN(sym, nmemb, size, __stackmem)
589 
590 /**
591  * @brief Define a toplevel array of thread stack memory regions in pinned section
592  *
593  * Create an array of equally sized stacks. See K_THREAD_STACK_DEFINE
594  * definition for additional details and constraints.
595  *
596  * This is the generic, historical definition. Align to Z_THREAD_STACK_OBJ_ALIGN
597  * and put in 'noinit' section so that it isn't zeroed at boot
598  *
599  * This puts the stack into the pinned noinit linker section if
600  * CONFIG_LINKER_USE_PINNED_SECTION is enabled, or else it would
601  * put the stack into the same section as K_THREAD_STACK_DEFINE().
602  *
603  * @param sym Thread stack symbol name
604  * @param nmemb Number of stacks to define
605  * @param size Size of the stack memory region
606  */
607 #if defined(CONFIG_LINKER_USE_PINNED_SECTION)
608 #define K_THREAD_PINNED_STACK_ARRAY_DEFINE(sym, nmemb, size) \
609 	Z_THREAD_PINNED_STACK_DEFINE_IN(sym, nmemb, size, __pinned_noinit)
610 #else
611 #define K_THREAD_PINNED_STACK_ARRAY_DEFINE(sym, nmemb, size) \
612 	K_THREAD_STACK_ARRAY_DEFINE(sym, nmemb, size)
613 #endif /* CONFIG_LINKER_USE_PINNED_SECTION */
614 
615 /** @} */
616 
617 /**
618  * @brief Get a pointer to the physical stack buffer
619  *
620  * Obtain a pointer to the non-reserved area of a stack object.
621  * This is not guaranteed to be the beginning of the thread-writable region;
622  * this does not account for any memory carved-out for MPU stack overflow
623  * guards.
624  *
625  * Use with care. The true bounds of the stack buffer are available in the
626  * stack_info member of its associated thread.
627  *
628  * @param sym defined stack symbol name
629  * @return The buffer itself, a char *
630  */
K_THREAD_STACK_BUFFER(k_thread_stack_t * sym)631 static inline char *K_THREAD_STACK_BUFFER(k_thread_stack_t *sym)
632 {
633 	return (char *)sym + K_THREAD_STACK_RESERVED;
634 }
635 
636 #endif /* CONFIG_USERSPACE */
637 
638 #ifdef __cplusplus
639 }
640 #endif
641 
642 #endif /* _ASMLANGUAGE */
643 #endif /* ZEPHYR_INCLUDE_KERNEL_THREAD_STACK_H */
644