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. I lost track about the review feedback for v1, partly because I asked Claude to integrate the review feedback for me, which it did, but not completely. Nevertheless I think this series has enough changes for now so that it deserves a second look. What I didn't care about yet is that we found out that neither ARM nor RiscV use any absolute relocations, so we might be able to remove support for them, make sure these are not emitted during compile time, or properly test/fix them when we discover that they are indeed needed. Co-Authored-By: Claude Sonnet 4.5 <[email protected]> Signed-off-by: Sascha Hauer <[email protected]> --- Changes in v2: - rebased on Ahmads patches and with it reused existing relocate_image() - hopefully integrated all feedback for v1 - Link to v1: https://lore.barebox.org/[email protected] --- Sascha Hauer (21): elf: only accept images matching the native ELF_CLASS elf: build for PBL as well elf: add dynamic relocation support ARM: implement elf_apply_relocations() for ELF relocation support riscv: define generic relocate_image 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: Allwinner D1: Drop M-Mode riscv: add ELF segment-based memory protection with MMU Makefile | 17 +- arch/arm/Kconfig | 2 + arch/arm/cpu/exceptions_32.S | 54 ++--- arch/arm/cpu/interrupts_32.c | 45 +++- arch/arm/cpu/mmu-common.c | 14 +- arch/arm/cpu/mmu-common.h | 3 +- arch/arm/cpu/mmu_32.c | 14 +- arch/arm/cpu/mmu_64.c | 10 +- arch/arm/cpu/no-mmu.c | 11 +- arch/arm/cpu/start.c | 11 +- arch/arm/cpu/uncompress.c | 40 +++- arch/arm/include/asm/barebox-arm.h | 4 +- arch/arm/include/asm/barebox.lds.h | 2 +- arch/arm/include/asm/elf.h | 7 + arch/arm/include/asm/sections.h | 1 + arch/arm/lib/pbl.lds.S | 6 +- arch/arm/lib32/barebox.lds.S | 38 ++- arch/arm/lib32/reloc.c | 23 ++ arch/arm/lib64/barebox.lds.S | 29 ++- arch/arm/lib64/reloc.c | 25 +- arch/riscv/Kconfig | 18 ++ arch/riscv/Kconfig.socs | 1 - arch/riscv/boot/start.c | 6 - arch/riscv/boot/uncompress.c | 43 +++- 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/barebox.lds.S | 38 +-- arch/riscv/lib/reloc.c | 82 +++++-- common/Makefile | 2 +- common/elf.c | 461 ++++++++++++++++++++++++++++++++++++- images/Makefile | 2 +- include/elf.h | 73 ++++++ include/mmu.h | 14 +- include/pbl/mmu.h | 29 +++ lib/Makefile | 1 + lib/elf_reloc.c | 15 ++ pbl/Kconfig | 9 + pbl/Makefile | 1 + pbl/mmu.c | 111 +++++++++ scripts/prelink-riscv.inc | 9 +- 43 files changed, 1685 insertions(+), 164 deletions(-) --- base-commit: fd86e9d4215bc4cd6a84af2a8de22f1bb9738faf change-id: 20251227-pbl-load-elf-cb4cb0ceb7d8 Best regards, -- Sascha Hauer <[email protected]>
