arm64: add protected mode support and SMP improvements

[hujun260]

Summary

This PR series adds comprehensive protected mode (CONFIG_BUILD_PROTECTED) support to ARM64
architecture, particularly for FVP platform, along with significant improvements to SMP
initialization and address environment functionality. The changes enable full kernel/user-space
isolation, simplify multi-core CPU synchronization, and extend address environment support
to MPU-based systems.

Changes Made

1. SMP Initialization Improvements

Remove Fixed Memory Address Configuration:

• Replace CONFIG_ARM64_SMP_BUSY_WAIT_FLAG_ADDR with global variable g_smp_busy_wait_flag
• Simplify multi-core CPU synchronization mechanism
• Align with standard kernel synchronization patterns
• Improve flexibility for different memory layouts
• Remove hardcoded address configuration requirement

Benefits:

• More flexible approach than fixed memory addresses
• Consistent with NuttX kernel variable patterns
• Cleaner configuration management
• Support for dynamic memory layout

2. FVP Protected Mode Build Support

Enable Protected Build Mode:

• Conditionally include fvp_userspace.c when CONFIG_BUILD_PROTECTED enabled
• Add user-space heap allocation support (fvp_v8r_allocateheap.c)
• Support kernel and user-space separation via MPU regions

Memory Map and Linker Scripts:

• Add board-specific board_memorymap.h definitions
• Create separate kernel and user-space linker scripts
• Support KTEXT, KSRAM, and UTEXT region definitions
• Enable dynamic memory layout configuration

Protected Mode Configuration:

• Add protected build configurations (pnsh, pnsh_smp)
• Configure MPU regions for kernel/user isolation
• Support kernel-space stack and user-space execution
• Enable proper privilege level management

3. ARM64 Core Protected Mode Support

Extend Protected Build Infrastructure:

• Add CONFIG_BUILD_PROTECTED support alongside CONFIG_BUILD_KERNEL
• Include arm64_task_start.c and arm64_pthread_start.c for protected mode
• Enable signal dispatch infrastructure

Context and Memory Management:

• Extend saved register pointer support for protected mode
• Enable weak heap allocation function for board customization
• Fix fork operation link register handling (Thumb bit masking)
• Add protected mode declarations and structures

Build System Updates:

• Update CMakeLists.txt for protected build compilation
• Update Make.defs for protected mode source inclusion
• Support both FLAT and PROTECTED build modes

4. Address Environment Support for MPU-Based Systems

Enable Addrenv in MPU-Only Systems:

• Wrap MMU-specific configuration checks with CONFIG_ARCH_USE_MMU guard
• Make CONFIG_MM_PGALLOC and CONFIG_MM_PGSIZE conditional on MMU
• Allow addrenv support in systems using MPU instead of MMU
• Enable mixed configurations supporting both MMU and MPU

Benefits:

• Support for MPU-based systems without paging
• Flexibility for different memory management approaches
• Cleaner configuration separation
• Better compatibility across architecture variants

---

Impact

SMP Improvements

• Simplified CPU synchronization without fixed memory addresses
• More flexible configuration approach
• Standard kernel synchronization patterns
• Cleaner assembly code

Protected Mode Support

• Full kernel/user-space isolation capability
• Board-specific customization options
• Proper privilege level management
• Signal dispatch and task management support

Address Environment

• Support for MPU-based systems
• Mixed MMU/MPU configuration support
• Cleaner configuration management
• Broader architecture support

Code Quality

• Simplified configuration requirements
• Cleaner separation of concerns
• Better maintainability
• Improved flexibility

---

Testing

Test Environment

• Linux x86_64 host with NuttX cross-compiler
• ARM64 FVP platform
• Multiple configurations: SMP, Protected mode, Protected mode SMP

Test Procedure

1. SMP Initialization:

   • Verify multi-core CPU synchronization without fixed addresses
   • Test concurrent operations
   • Confirm no synchronization issues

2. Protected Mode:

   • Build with CONFIG_BUILD_PROTECTED
   • Boot in protected mode
   • Verify kernel/user-space isolation
   • Test user-space application execution

3. Address Environment:

   • Test addrenv in protected mode
   • Verify MPU-based addrenv support
   • Confirm backward compatibility

4. Integration:

   • Run NuttX test suite
   • Verify no regressions
   • Test device driver operations

Test Results

✅ SMP synchronization operational without fixed addresses
✅ Protected mode isolation enforced
✅ Address environment supports MPU-based systems
✅ All configurations compile successfully
✅ No test suite regressions
✅ Backward compatibility maintained

---

Verification Checklist

• ✅ No JIRA IDs or internal identifiers
• ✅ Commit messages follow NuttX conventions
• ✅ Public API compatibility preserved
• ✅ Configuration options properly guarded
• ✅ Build system files updated
• ✅ Protected mode fully functional
• ✅ SMP improvements operational
• ✅ Address environment extended to MPU systems
• ✅ Backward compatibility maintained
• ✅ All tests passing

---

Related Commits

• ff4ac88811d - arm64: remove busy wait flag
• 3905065eede - fvp-v8r: protect build support
• d3c187322df - arm64: support protectbuild
• 573bafbd880 - addrenv: support addrenv when mpu is used

[jerpelea]

please split the PR in separate areas:

• MPU enhancements
• interface standardization
• Protected more support

[hujun260]

please split the PR in separate areas:

• MPU enhancements
• interface standardization
• Protected more support

done

[jerpelea]

please split the PR in separate areas:

• MPU enhancements
• interface standardization
• Protected more support

done

sorry for the misunderstanding
I was suggesting 3 PRs (1 for each area)
Best regards

[hujun260]

please split the PR in separate areas:

• MPU enhancements
• interface standardization
• Protected more support

done

sorry for the misunderstanding I was suggesting 3 PRs (1 for each area) Best regards
done