kernel: expose k_mem_partition_attr_t outside User mode

This commit exposes k_mem_partition_attr_t outside User Mode, so
we can use struct k_mem_partition for defining memory partitions
outside the scope of user space (for example, to describe thread
stack guards or no-cacheable MPU regions). A requirement is that
the Zephyr build supports Memory protection. To signify this, a
new hidden, all-architecture Kconfig symbol is defined (MPU). In
the wake of exposing k_mem_partition_attr_t, the commit exposes
the MPU architecture-specific access permission attribute macros
outside the User space context (for all ARCHs), so they can be
used in a more generic way.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

arch/Kconfig

@@ -393,6 +393,14 @@ config CPU_HAS_MPU
 	help
 	  This option is enabled when the CPU has a Memory Protection Unit (MPU).
 
+config MEMORY_PROTECTION
+	bool
+	# Omit prompt to signify "hidden" option
+	help
+	  This option is enabled when Memory Protection features are supported.
+	  Memory protection support is currently available on ARC, ARM, and x86
+	  architectures.
+
 config MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT
 	bool
 	# Omit prompt to signify "hidden" option

arch/arc/core/mpu/Kconfig

@@ -31,6 +31,7 @@ config ARC_MPU
 	depends on CPU_HAS_MPU
 	select ARC_CORE_MPU
 	select THREAD_STACK_INFO
+	select MEMORY_PROTECTION
 	select MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT if ARC_MPU_VER = 2
 	help
 	  Target has ARC MPU (currently only works for EMSK 2.2/2.3 ARCEM7D)

arch/arm/core/cortex_m/mpu/Kconfig

@@ -9,6 +9,7 @@
 config ARM_MPU
 	bool "ARM MPU Support"
 	depends on CPU_HAS_MPU
+	select MEMORY_PROTECTION
 	select THREAD_STACK_INFO
 	select ARCH_HAS_EXECUTABLE_PAGE_BIT
 	select MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT if !(CPU_HAS_NXP_MPU || ARMV8_M_BASELINE || ARMV8_M_MAINLINE)

arch/x86/Kconfig

@@ -64,6 +64,7 @@ config X86_IAMCU
 menu "Memory Management"
 config X86_MMU
 	bool "Enable Memory Management Unit"
+	select MEMORY_PROTECTION
 	help
 	  This options enables the memory management unit present in x86. Enabling
 	  this will create boot time page table structure.

arch/x86/include/mmustructs.h

@@ -243,7 +243,7 @@
 
 #endif	/* CONFIG_X86_PAE_MODE */
 
-#ifdef CONFIG_X86_USERSPACE
+#ifdef CONFIG_X86_MMU
 
 /* Flags which are only available for PAE mode page tables  */
 #ifdef CONFIG_X86_PAE_MODE
@@ -297,7 +297,7 @@
 
 #endif	/* CONFIG_X86_PAE_MODE */
 
-#endif	 /* CONFIG_X86_USERSPACE */
+#endif	 /* CONFIG_X86_MMU */
 
 #ifndef _ASMLANGUAGE
 #include <zephyr/types.h>

include/arch/arc/arch.h

@@ -155,7 +155,6 @@ extern "C" {
 #endif /* CONFIG_USERSPACE */
 
 
-#ifdef CONFIG_USERSPACE
 #ifdef CONFIG_ARC_MPU
 #ifndef _ASMLANGUAGE
 #include <arch/arc/v2/mpu/arc_mpu.h>
@@ -217,7 +216,6 @@ extern "C" {
 		"start address of the partition must align with 32.")
 #endif
 #endif /* CONFIG_ARC_MPU*/
-#endif /* CONFIG_USERSPACE */
 
 #ifndef _ASMLANGUAGE
 /* Typedef for the k_mem_partition attribute*/

include/arch/arm/arch.h

@@ -252,7 +252,7 @@ extern "C" {
 #define _ARCH_THREAD_STACK_BUFFER(sym) \
 		((char *)(sym) + MPU_GUARD_ALIGN_AND_SIZE)
 
-#ifdef CONFIG_USERSPACE
+#ifdef CONFIG_ARM_MPU
 #ifdef CONFIG_CPU_HAS_ARM_MPU
 #ifndef _ASMLANGUAGE
 #include <arch/arm/cortex_m/mpu/arm_mpu.h>
@@ -323,8 +323,8 @@ extern "C" {
 		" and greater than or equal to minimum MPU region size." \
 		"start address of the partition must align with minimum MPU \
 		 region size.")
-#endif  /* CONFIG_CPU_HAS_ARM_MPU */
+#endif  /* CONFIG_CPU_HAS_NXP_MPU */
-#endif /* CONFIG_USERSPACE */
+#endif /* CONFIG_ARM_MPU */
 
 #ifndef _ASMLANGUAGE
 /* Typedef for the k_mem_partition attribute*/

include/arch/arm/cortex_m/mpu/arm_mpu_v7m.h

@@ -129,7 +129,6 @@ struct arm_mpu_region_attr {
 
 typedef struct arm_mpu_region_attr arm_mpu_region_attr_t;
 
-#ifdef CONFIG_USERSPACE
 #ifndef _ASMLANGUAGE
 /* Read-Write access permission attributes */
 #define K_MEM_PARTITION_P_NA_U_NA	(NO_ACCESS_Msk | NOT_EXEC)
@@ -162,4 +161,3 @@ typedef struct arm_mpu_region_attr arm_mpu_region_attr_t;
 #define K_MEM_PARTITION_IS_EXECUTABLE(attr) \
 	(!((attr) & (NOT_EXEC)))
 #endif /* _ASMLANGUAGE */
-#endif /* USERSPACE */

include/arch/arm/cortex_m/mpu/arm_mpu_v8m.h

@@ -139,7 +139,6 @@ struct arm_mpu_region_attr {
 
  typedef struct arm_mpu_region_attr arm_mpu_region_attr_t;
 
-#ifdef CONFIG_USERSPACE
 #ifndef _ASMLANGUAGE
 /* Read-Write access permission attributes */
 #define K_MEM_PARTITION_P_RW_U_RW	(P_RW_U_RW_Msk | NOT_EXEC)
@@ -168,4 +167,3 @@ struct arm_mpu_region_attr {
 #define K_MEM_PARTITION_IS_EXECUTABLE(attr) \
 	(!((attr) & (NOT_EXEC)))
 #endif /* _ASMLANGUAGE */
-#endif /* USERSPACE */

include/kernel.h

@@ -4781,10 +4781,10 @@ struct k_mem_partition {
 	u32_t start;
 	/* size of memory partition */
 	u32_t size;
-#ifdef CONFIG_USERSPACE
+#if defined(CONFIG_MEMORY_PROTECTION)
 	/* attribute of memory partition */
 	k_mem_partition_attr_t attr;
-#endif	/* CONFIG_USERSPACE */
+#endif /* CONFIG_MEMORY_PROTECTION */
 };
 
 /* memory domain