[arm][cortex-m4] Add hardware stack guard support - #11740
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📌 Code Review Assignment🏷️ Tag: bsp_stm32Reviewers: @Liang1795 @hamburger-os @wdfk-prog Changed Files (Click to expand)
📊 Current Review Status (Last Updated: 2026-08-24 13:51 CST)
📝 Review Instructions
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Enable RT_USING_HW_STACK_GUARD on Cortex-M4, which was previously only available on Cortex-M7 and Cortex-M33. Core porting (libcpu/arm/cortex-m4/): - Add mpu.c/mpu.h/mputype.h aligned with the Cortex-M7 MPU layer. The only difference is the default memory type attribute: Cortex-M4 has no L1 cache, so the cacheability bits are reduced to three cases. - Add rt_hw_stack_guard_init() to cpuport.c. - Add missing #include <rtconfig.h> to context_gcc.S and invoke rt_hw_mpu_table_switch() in the PendSV context switch path. - Update SConscript to exclude mpu.c when memory protection is disabled. BSP reference (bsp/stm32/stm32f407-fk407m2-zgt6/): - board.h: include rtthread.h and define NUM_STATIC_REGIONS. - board.c: define static_regions[] marking the Flash region read-only, guarded by RT_USING_MEM_PROTECTION so it is not enabled by default.
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Pull request overview
This PR adds Cortex-M4 support for RT-Thread’s RT_USING_HW_STACK_GUARD (hardware stack overflow protection) by introducing an MPU backend aligned with existing Cortex-M7 / Cortex-M33 implementations, and wiring MPU table switching into the PendSV context switch path.
本次 PR 为 Cortex-M4 补齐 RT_USING_HW_STACK_GUARD（硬件栈保护）能力：新增与 Cortex-M7/M33 对齐的 MPU 后端，并在 PendSV 上下文切换路径中切换线程对应的 MPU 表。
Changes / 变更点：
- Add Cortex-M4 MPU abstraction + implementation (
mpu.c/.h,mputype.h) to support memory protection and stack guard.
新增 Cortex-M4 的 MPU 抽象与实现（mpu.c/.h,mputype.h），用于内存保护与栈保护。 - Add
rt_hw_stack_guard_init()for Cortex-M4 and integrate MPU table switching intocontext_gcc.SPendSV path.
Cortex-M4 增加rt_hw_stack_guard_init()，并在context_gcc.S的 PendSV 路径中调用rt_hw_mpu_table_switch()。 - Provide an STM32F407 BSP reference static MPU region definition (Flash RX) guarded by
RT_USING_MEM_PROTECTION.
提供 STM32F407 BSP 参考实现：在RT_USING_MEM_PROTECTION条件下定义静态 MPU 区域（Flash 只读可执行）。
Reviewed changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| libcpu/arm/cortex-m4/SConscript | Excludes mpu.c when neither mem protection nor stack guard is enabled |
| libcpu/arm/cortex-m4/mputype.h | Adds Cortex-M4 rt_mem_attr_t and dynamic region count definitions |
| libcpu/arm/cortex-m4/mpu.h | Adds Cortex-M4 MPU permission/type macros and MPU APIs |
| libcpu/arm/cortex-m4/mpu.c | Implements MPU init/region ops/table switch + MemManage handler for Cortex-M4 |
| libcpu/arm/cortex-m4/cpuport.c | Adds rt_hw_stack_guard_init() and adjusts formatting in several areas |
| libcpu/arm/cortex-m4/context_gcc.S | Includes rtconfig.h and switches MPU table during PendSV context restore |
| bsp/stm32/stm32f407-fk407m2-zgt6/board/board.h | Adds NUM_STATIC_REGIONS definition under mem protection |
| bsp/stm32/stm32f407-fk407m2-zgt6/board/board.c | Adds static_regions[] (Flash RX) under mem protection |
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| __asm int __rt_ffs(int value) | ||
| { | ||
| CMP r0, #0x00 | ||
| BEQ exit | ||
| CMP r0, #0x00 BEQ exit | ||
|
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||
| RBIT r0, r0 | ||
| CLZ r0, r0 | ||
| ADDS r0, r0, #0x01 | ||
| RBIT r0, |
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已修复。Fixed.
The __rt_ffs inline assembly has been restored to the correct ARMCC syntax (same as the Cortex-M7 implementation), and wrapped with // clang-format off / // clang-format on to prevent the automatic clang-format workflow from corrupting it again.
已将 __rt_ffs 内联汇编恢复为正确的 ARMCC 语法（与 Cortex-M7 实现一致），并用 // clang-format off / // clang-format on 包裹，防止格式化工作流再次破坏。
Restore the ARMCC __rt_ffs inline assembly that was corrupted by the automatic clang-format commit, which merged multiple instructions onto one line and split labels across lines, making it invalid ARMCC syntax. Wrap the block with // clang-format off/on to prevent future formatting runs from breaking it again.
Description / 描述
为 Cortex-M4 补齐
RT_USING_HW_STACK_GUARD硬件栈保护支持。此前该能力仅 Cortex-M7 和 Cortex-M33 可用，M4（尤其是大量 STM32F4 BSP）缺失。Add hardware stack guard support for Cortex-M4, which was previously only available on Cortex-M7 and Cortex-M33.
Why / 为什么
栈溢出是嵌入式系统最高频、最隐蔽的故障之一。Cortex-M4 同样具备 MPU，但 RT-Thread 的 mprotect 框架尚未在 M4 上落地
rt_hw_stack_guard_init。Stack overflow is one of the most common and hardest-to-debug faults in embedded systems. Cortex-M4 has an MPU, but the mprotect framework has not yet provided
rt_hw_stack_guard_initon M4.Modified Files / 修改文件
核心移植 core porting (
libcpu/arm/cortex-m4/):mpu.c/mpu.h/mputype.h（新增）：对齐 Cortex-M7 的 MPU 抽象层。唯一差异在默认内存类型属性——M4 无 L1 cache，cacheability 位简化为三种情况。cpuport.c：新增rt_hw_stack_guard_init()。context_gcc.S：补上缺失的#include <rtconfig.h>，并在 PendSV 上下文切换路径中调用rt_hw_mpu_table_switch()。SConscript：未开启内存保护时排除mpu.c。BSP 参考实现 (
bsp/stm32/stm32f407-fk407m2-zgt6/board/):board.h：includertthread.h，定义NUM_STATIC_REGIONS（#ifdef保护）。board.c：定义static_regions[]（Flash 区域只读，#ifdef保护，不默认开启）。Verification / 验证
RT_USING_HW_STACK_GUARD两种配置均通过；frdm-k64f无回归）。