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zephyr/include/arch/arm/arch.h
Ioannis Glaropoulos e0db39447b arch: arm: re-organize thread stack macro defines in arch.h 
This commit re-organizes the macro definitions in arch.h for
the ARM architecture. In particular, the commit:
- defines the minimum alignment requirement for thread stacks,
  that is, excluding alignment requirement for (possible)
  MPU stack guards.
- defines convenience macros for the MPU stack guard align and
  size for threads using the FP services under Shared registers
  mode (CONFIG_FP_SHARING=y). For that, a hidden Kconfig option
  is defined in arch/arm/core/cortex_m/mpu/Kconfig.
- enforces stack alignment with a wide MPU stack guard (128
  bytes) under CONFIG_FP_SHARING=y for the ARMv7-M architecture,
  which requires start address alignment with power-of-two and
  region size.

The commit does not change the amount of stack that is reserved
with K_THREAD_STACK_DEFINE; it only determines the stack buffer
alignment as explained above.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
2019-06-24 10:16:57 -07:00

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/*
* Copyright (c) 2013-2014 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief ARM specific kernel interface header
*
* This header contains the ARM specific kernel interface. It is
* included by the kernel interface architecture-abstraction header
* (include/arm/cpu.h)
*/
#ifndef ZEPHYR_INCLUDE_ARCH_ARM_ARCH_H_
#define ZEPHYR_INCLUDE_ARCH_ARM_ARCH_H_
/* Add include for DTS generated information */
#include <generated_dts_board.h>
/* ARM GPRs are often designated by two different names */
#define sys_define_gpr_with_alias(name1, name2) union { u32_t name1, name2; }
#ifdef CONFIG_CPU_CORTEX_M
#include <arch/arm/cortex_m/exc.h>
#include <arch/arm/cortex_m/irq.h>
#include <arch/arm/cortex_m/error.h>
#include <arch/arm/cortex_m/misc.h>
#include <arch/arm/cortex_m/memory_map.h>
#include <arch/arm/cortex_m/asm_inline.h>
#include <arch/common/sys_io.h>
#include <arch/common/addr_types.h>
#include <arch/common/ffs.h>
#include <arch/arm/cortex_m/nmi.h>
#endif
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Declare the STACK_ALIGN_SIZE
*
* Denotes the required alignment of the stack pointer on public API
* boundaries
*
*/
#ifdef CONFIG_STACK_ALIGN_DOUBLE_WORD
#define STACK_ALIGN_SIZE 8
#else
#define STACK_ALIGN_SIZE 4
#endif
/**
* @brief Declare the minimum alignment for a thread stack
*
* Denotes the minimum required alignment of a thread stack.
*
* Note:
* User thread stacks must respect the minimum MPU region
* alignment requirement.
*/
#if defined(CONFIG_USERSPACE)
#define Z_THREAD_MIN_STACK_ALIGN CONFIG_ARM_MPU_REGION_MIN_ALIGN_AND_SIZE
#else
#define Z_THREAD_MIN_STACK_ALIGN STACK_ALIGN_SIZE
#endif
/**
* @brief Declare a minimum MPU guard alignment and size
*
* This specifies the minimum MPU guard alignment/size for the MPU. This
* will be used to denote the guard section of the stack, if it exists.
*
* One key note is that this guard results in extra bytes being added to
* the stack. APIs which give the stack ptr and stack size will take this
* guard size into account.
*
* Stack is allocated, but initial stack pointer is at the end
* (highest address). Stack grows down to the actual allocation
* address (lowest address). Stack guard, if present, will comprise
* the lowest MPU_GUARD_ALIGN_AND_SIZE bytes of the stack.
*
* As the stack grows down, it will reach the end of the stack when it
* encounters either the stack guard region, or the stack allocation
* address.
*
* ----------------------- <---- Stack allocation address + stack size +
* | | MPU_GUARD_ALIGN_AND_SIZE
* | Some thread data | <---- Defined when thread is created
* | ... |
* |---------------------| <---- Actual initial stack ptr
* | Initial Stack Ptr | aligned to STACK_ALIGN_SIZE
* | ... |
* | ... |
* | ... |
* | ... |
* | ... |
* | ... |
* | ... |
* | ... |
* | Stack Ends |
* |---------------------- <---- Stack Buffer Ptr from API
* | MPU Guard, |
* | if present |
* ----------------------- <---- Stack Allocation address
*
*/
#if defined(CONFIG_MPU_STACK_GUARD)
#define MPU_GUARD_ALIGN_AND_SIZE CONFIG_ARM_MPU_REGION_MIN_ALIGN_AND_SIZE
#else
#define MPU_GUARD_ALIGN_AND_SIZE 0
#endif
/**
* @brief Declare the MPU guard alignment and size for a thread stack
* that is using the Floating Point services.
*
* For threads that are using the Floating Point services under Shared
* Registers (CONFIG_FP_SHARING=y) mode, the exception stack frame may
* contain both the basic stack frame and the FP caller-saved context,
* upon exception entry. Therefore, a wide guard region is required to
* guarantee that stack-overflow detection will always be successful.
*/
#if defined(CONFIG_FLOAT) && defined(CONFIG_FP_SHARING) \
&& defined(CONFIG_MPU_STACK_GUARD)
#define MPU_GUARD_ALIGN_AND_SIZE_FLOAT CONFIG_MPU_STACK_GUARD_MIN_SIZE_FLOAT
#else
#define MPU_GUARD_ALIGN_AND_SIZE_FLOAT 0
#endif
/**
* @brief Define alignment of an MPU guard
*
* Minimum alignment of the start address of an MPU guard, depending on
* whether the MPU architecture enforces a size (and power-of-two) alignment
* requirement.
*/
#if defined(CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT)
#define Z_MPU_GUARD_ALIGN (MAX(MPU_GUARD_ALIGN_AND_SIZE, \
MPU_GUARD_ALIGN_AND_SIZE_FLOAT))
#else
#define Z_MPU_GUARD_ALIGN MPU_GUARD_ALIGN_AND_SIZE
#endif
/**
* @brief Define alignment of a stack buffer
*
* This is used for two different things:
* 1) Used in checks for stack size to be a multiple of the stack buffer
* alignment
* 2) Used to determine the alignment of a stack buffer
*
*/
#define STACK_ALIGN MAX(Z_THREAD_MIN_STACK_ALIGN, Z_MPU_GUARD_ALIGN)
/**
* @brief Calculate power of two ceiling for a buffer size input
*
*/
#define POW2_CEIL(x) ((1 << (31 - __builtin_clz(x))) < x ? \
1 << (31 - __builtin_clz(x) + 1) : \
1 << (31 - __builtin_clz(x)))
#if defined(CONFIG_USERSPACE) && \
defined(CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT)
/* Guard is 'carved-out' of the thread stack region, and the supervisor
* mode stack is allocated elsewhere by gen_priv_stack.py
*/
#define Z_ARCH_THREAD_STACK_RESERVED 0
#else
#define Z_ARCH_THREAD_STACK_RESERVED MPU_GUARD_ALIGN_AND_SIZE
#endif
#if defined(CONFIG_USERSPACE) && \
defined(CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT)
#define Z_ARCH_THREAD_STACK_DEFINE(sym, size) \
struct _k_thread_stack_element __noinit \
__aligned(POW2_CEIL(size)) sym[POW2_CEIL(size)]
#else
#define Z_ARCH_THREAD_STACK_DEFINE(sym, size) \
struct _k_thread_stack_element __noinit __aligned(STACK_ALIGN) \
sym[size+MPU_GUARD_ALIGN_AND_SIZE]
#endif
#if defined(CONFIG_USERSPACE) && \
defined(CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT)
#define Z_ARCH_THREAD_STACK_LEN(size) (POW2_CEIL(size))
#else
#define Z_ARCH_THREAD_STACK_LEN(size) ((size)+MPU_GUARD_ALIGN_AND_SIZE)
#endif
#if defined(CONFIG_USERSPACE) && \
defined(CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT)
#define Z_ARCH_THREAD_STACK_ARRAY_DEFINE(sym, nmemb, size) \
struct _k_thread_stack_element __noinit \
__aligned(POW2_CEIL(size)) \
sym[nmemb][Z_ARCH_THREAD_STACK_LEN(size)]
#else
#define Z_ARCH_THREAD_STACK_ARRAY_DEFINE(sym, nmemb, size) \
struct _k_thread_stack_element __noinit \
__aligned(STACK_ALIGN) \
sym[nmemb][Z_ARCH_THREAD_STACK_LEN(size)]
#endif
#if defined(CONFIG_USERSPACE) && \
defined(CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT)
#define Z_ARCH_THREAD_STACK_MEMBER(sym, size) \
struct _k_thread_stack_element __aligned(POW2_CEIL(size)) \
sym[POW2_CEIL(size)]
#else
#define Z_ARCH_THREAD_STACK_MEMBER(sym, size) \
struct _k_thread_stack_element __aligned(STACK_ALIGN) \
sym[size+MPU_GUARD_ALIGN_AND_SIZE]
#endif
#define Z_ARCH_THREAD_STACK_SIZEOF(sym) (sizeof(sym) - MPU_GUARD_ALIGN_AND_SIZE)
#define Z_ARCH_THREAD_STACK_BUFFER(sym) \
((char *)(sym) + MPU_GUARD_ALIGN_AND_SIZE)
#ifdef CONFIG_ARM_MPU
#ifdef CONFIG_CPU_HAS_ARM_MPU
#include <arch/arm/cortex_m/mpu/arm_mpu.h>
#endif /* CONFIG_CPU_HAS_ARM_MPU */
#ifdef CONFIG_CPU_HAS_NXP_MPU
#include <arch/arm/cortex_m/mpu/nxp_mpu.h>
#endif /* CONFIG_CPU_HAS_NXP_MPU */
#endif /* CONFIG_ARM_MPU */
#ifdef __cplusplus
}
#endif
#endif /* ZEPHYR_INCLUDE_ARCH_ARM_ARCH_H_ */
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