feat(non-unified-mem): introduce support for non unified memory platforms

[danielRep]

PR Description

This PR builds on top of PR #216 and adds support for platforms with non-unified memory architectures—i.e., platforms where code (e.g., flash) and data (e.g., SRAM) reside in separate memory regions. Previously, Bao only supported platforms with unified DRAM-based memory.
To support this architectural change, the following modifications were made:

• Refactored Bao’s memory reservation logic to handle the distinction between code and data memory.
• Removed the load_addr argument from function calls within mem.c, as it is now a constant global variable. Passing it explicitly no longer made sense in the context of non-unified memory platforms.
• Added memory permissions classification to reflect platform's memory restrictions (e.g., flash is read-only)
• Refactored the linkerscript to add the concept of VMA (Virtual Memory Address) and LMA (Load Memory Address)

Refactored LinkerScript

The following table details the difference between the memory layout of unified vs non-unified platforms. Unified platforms keep the same layout as expected while non-unified platforms split addresses between VMA and LMA addresses to cope with the typical separation of code and data memory architecture.

Unified Platforms

fvp-r-aarch32

Sections	Address (bottom)	Linker Symbols
	(top) 0x0001fe40	_image_end; _dmem_beg
.bss	0x0001cec0	_image_noload_start; _vm_image_end
.vm_images	0x0000cec0	_image_load_end; _vm_image_start
.ipi_cpumsg_handlers_id	...
.ipi_cpumsg_handlers	...
.data	0x0000c880
.rodata	0x0000ba00
.text	0x00000300
.boot	0x00000000	_image_start

qemu-aarch64-virt

Sections	Addresses (bottom)	Linker Symbols
	0xfd800002c000	_image_noload_start; _vm_image_end
	0xfd8000020000	_image_end; _dmem_beg
.glb_page_tables	0xfd800001c000
.bss	0xfd8000013000
.vm_images	0xfd8000013000	_image_load_end; _vm_image_start
.ipi_cpumsg_handlers_id	...
.ipi_cpumsg_handlers	...
.data	0xfd8000012000
.rodata	0xfd8000010000
.text	0xfd8000000800
.boot	0xfd8000000000	_image_start

Non-Unified Platform

tricore tc49

Sections	Addresses (bottom)	Linker Symbols
	0x90008e40	_image_end; _dmem_beg
.bss	0x900014c0	_image_noload_start; _bss_start
	0x800172c0	_vm_image_end
.vm_images	0x800130c0	_image_load_end; _vm_image_start
.ipi_cpumsg_handlers_id	...
.ipi_cpumsg_handlers	...
.data	0x90000000	_data_vma_start
.data : AT(_data_lma_start)	0x80011c00	_data_lma_start
.rodata	0x80010f80
.text	0x80000300
.boot	0x80000000	_image_start

[DavidMCerdeira]

In the PR description, alongside the other modifications, I also suggest adding that it is now possible to setup memory permissions to reflect platform's memory restrictions (e.g., flash is read-only)

[josecm]

@danielRep can we rebase this on ref/vmpu?

[danielRep]

@danielRep can we rebase this on ref/vmpu?

Done.

[josecm]

@danielRep please rebase on main and clean up commit history before proceeding

[josecm]

@DavidMCerdeira @miguelafsilva5 please give another pass when possible

[miguelafsilva5]

@DavidMCerdeira @miguelafsilva5 please give another pass when possible

@josecm I've given it another pass and rebased it to TC4. Everything is working and seems OK