[PATCH 00/19] PBL: Add PBL ELF loading support with dynamic relocations

[Sascha Hauer]

Until now we linked the raw barebox proper binary into the PBL which
comes with a number of disadvantages. We rely on self-modifying code
to in barebox proper (relocate_to_current_adr()) and have no initialized
bss segment (setup_c()). Also we can only mark the .text and .rodata as
readonly during runtime of barebox proper.

This series overcomes this by linking a ELF image into the PBL. This
image is properly layed out, linked and initialized in the PBL. With
this barebox proper has a proper C environment and text/rodata
protection from the start.

As a bonus this series also adds initial MMU support for RISCV, also
based on loading the ELF image and configuring the MMU from the PBL.

This series also marks my start into AI assisted programming as you can
see in the Co-Authored-By: Claude Sonnet 4.5 <noreply at anthropic.com>
and 🤖 Generated with [Claude Code](https://claude.com/claude-code)
tags. Without it I wouldn't have started this series during my xmas
break, but with it it was actually quite fun to do; it felt like having
a programming team which I just had to delegate new tasks to while
having fun with my family myself ;)

Co-Authored-By: Claude Sonnet 4.5 <noreply at anthropic.com>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
Sascha Hauer (19):
      elf: Use memcmp to make suitable for PBL
      elf: build for PBL as well
      elf: add dynamic relocation support
      ARM: implement elf_apply_relocations() for ELF relocation support
      riscv: implement elf_apply_relocations() for ELF relocation support
      elf: implement elf_load_inplace()
      elf: create elf_open_binary_into()
      Makefile: add barebox.elf build target
      PBL: allow to link ELF image into PBL
      mmu: add MAP_CACHED_RO mapping type
      mmu: introduce pbl_remap_range()
      ARM: use relative jumps in exception table
      ARM: exceptions: make in-binary exception table const
      ARM: linker script: create separate PT_LOAD segments for text, rodata, and data
      ARM: link ELF image into PBL
      ARM: PBL: setup MMU with proper permissions from ELF segments
      riscv: link ELF image into PBL
      riscv: linker script: create separate PT_LOAD segments for text, rodata, and data
      riscv: add ELF segment-based memory protection with MMU

 Makefile                           |  16 +-
 arch/arm/Kconfig                   |   2 +
 arch/arm/cpu/exceptions_32.S       |  54 +++---
 arch/arm/cpu/interrupts_32.c       |  41 +++-
 arch/arm/cpu/mmu-common.c          |  66 +------
 arch/arm/cpu/mmu-common.h          |   3 +-
 arch/arm/cpu/mmu_32.c              |  19 +-
 arch/arm/cpu/mmu_64.c              |  10 +-
 arch/arm/cpu/no-mmu.c              |  11 +-
 arch/arm/cpu/start.c               |   4 -
 arch/arm/cpu/uncompress.c          |  46 ++++-
 arch/arm/include/asm/barebox-arm.h |   4 +-
 arch/arm/include/asm/barebox.lds.h |  14 +-
 arch/arm/include/asm/elf.h         |  11 ++
 arch/arm/include/asm/sections.h    |   1 +
 arch/arm/lib/pbl.lds.S             |   8 +-
 arch/arm/lib32/Makefile            |   1 +
 arch/arm/lib32/barebox.lds.S       |  39 ++--
 arch/arm/lib32/elf_reloc.c         | 105 ++++++++++
 arch/arm/lib64/Makefile            |   1 +
 arch/arm/lib64/barebox.lds.S       |  31 ++-
 arch/arm/lib64/elf_reloc.c         | 105 ++++++++++
 arch/riscv/Kconfig                 |  18 ++
 arch/riscv/Kconfig.socs            |   1 -
 arch/riscv/boot/start.c            |   4 -
 arch/riscv/boot/uncompress.c       |  41 +++-
 arch/riscv/cpu/Makefile            |   1 +
 arch/riscv/cpu/mmu.c               | 386 +++++++++++++++++++++++++++++++++++++
 arch/riscv/cpu/mmu.h               | 144 ++++++++++++++
 arch/riscv/include/asm/asm.h       |   3 +-
 arch/riscv/include/asm/mmu.h       |  44 +++++
 arch/riscv/lib/Makefile            |   1 +
 arch/riscv/lib/barebox.lds.S       |  38 ++--
 arch/riscv/lib/elf_reloc.c         | 212 ++++++++++++++++++++
 common/Makefile                    |   2 +-
 common/elf.c                       | 367 +++++++++++++++++++++++++++++++++--
 images/Makefile                    |  18 +-
 images/piggy.S                     |   4 +
 include/elf.h                      |  62 ++++++
 include/mmu.h                      |  12 +-
 include/pbl/mmu.h                  |  29 +++
 lib/Makefile                       |   1 +
 lib/elf_reloc.c                    |  15 ++
 pbl/Kconfig                        |   8 +
 pbl/Makefile                       |   1 +
 pbl/mmu.c                          | 111 +++++++++++
 scripts/prelink-riscv.inc          |   9 +-
 47 files changed, 1922 insertions(+), 202 deletions(-)
---
base-commit: e2d7e032281158b54541392b4d8108de204137a1
change-id: 20251227-pbl-load-elf-cb4cb0ceb7d8

Best regards,
-- 
Sascha Hauer <s.hauer at pengutronix.de>