include/misc/stack.h

/**
 * @file stack.h
 * Stack usage analysis helpers
 */

/*
 * Copyright (c) 2015 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#ifndef ZEPHYR_INCLUDE_MISC_STACK_H_
#define ZEPHYR_INCLUDE_MISC_STACK_H_

#include <logging/log.h>
#include <stdbool.h>

static inline size_t stack_unused_space_get(const char *stack, size_t size)
{
	size_t unused = 0;

	if (IS_ENABLED(CONFIG_INIT_STACKS)) {
		const unsigned char *checked_stack =
			(const unsigned char *)stack;

		if (IS_ENABLED(CONFIG_STACK_SENTINEL)) {
			/* First 4 bytes of the stack buffer reserved for the
			 * sentinel value, it won't be 0xAAAAAAAA for thread
			 * stacks.
			 */
			checked_stack += 4;
		}

		/* TODO Currently all supported platforms have stack growth down
		 * and there is no Kconfig option to configure it so this always
		 * build "else" branch.
		 * When support for platform with stack direction up
		 * (or configurable direction) is added this check should be
		 * confirmed that correct Kconfig option is used.
		 */
		if (IS_ENABLED(CONFIG_STACK_GROWS_UP)) {
			for (size_t i = size; i > 0; i--) {
				if (checked_stack[i - 1] == 0xaaU) {
					unused++;
				} else {
					break;
				}
			}
		} else {
			for (size_t i = 0; i < size; i++) {
				if (checked_stack[i] == 0xaaU) {
					unused++;
				} else {
					break;
				}
			}
		}
	}

	return unused;
}

static inline void stack_analyze(const char *name, const char *stack,
				 unsigned int size)
{
	if (IS_ENABLED(CONFIG_INIT_STACKS)) {
		LOG_MODULE_DECLARE(kernel, CONFIG_KERNEL_LOG_LEVEL);

		unsigned int unused = stack_unused_space_get(stack, size);
		unsigned int pcnt = ((size - unused) * 100) / size;

		LOG_INF("%s :\tunused %u\tusage %u / %u (%u %%)",
			name, unused, size - unused, size, pcnt);
	}
}

/**
 * @brief Analyze stacks.
 *
 * Use this macro to get information about stack usage.
 *
 * @param name Name of the stack
 * @param sym The symbol of the stack
 */
#define STACK_ANALYZE(name, sym)				\
	do {							\
		stack_analyze(name,				\
			      K_THREAD_STACK_BUFFER(sym),	\
			      K_THREAD_STACK_SIZEOF(sym));	\
	} while (false)

#endif /* ZEPHYR_INCLUDE_MISC_STACK_H_ */