[PATCH v4 00/22] PBL: Add PBL ELF loading support with dynamic relocations
Ahmad Fatoum
a.fatoum at pengutronix.de
Thu Jan 15 04:44:44 PST 2026
Hello Sascha,
On 1/14/26 1:14 PM, Sascha Hauer wrote:
> 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.
I am done with my review, so as far as I am concerned, this series can
go in with the minor points mentioned addressed.
Thanks,
Ahmad
>
> Co-Authored-By: Claude Sonnet 4.5 <noreply at anthropic.com>
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> ---
> Changes in v4:
> - remove --remove-section=.note.gnu.build-id, catched by
> --remove-section=.note*
> - actually use __image_* in remap_range_end_sans_image()
> - drop pbl_remap_range in favor of remap_range()
> - drop duplicate ELF entry point pr_debug()
> - add static inline wrapper for pbl_mmu_setup_from_elf()
> - reorder segments
> - make dynamic section RO
> - introduce elf_for_each_segment()
> - Use lowest vaddr segment for base address
> - Link to v3: https://lore.barebox.org/20260108-pbl-load-elf-v3-0-e28c931fc179@pengutronix.de
>
> Changes in v3:
> - integrate Ahmads feedback
> - cleanup barebox proper entry
> - add missing "ax" flag to ARM exception table, and let linker do the
> fixup
> - Link to v2: https://lore.barebox.org/20260106-pbl-load-elf-v2-0-487bc760f045@pengutronix.de
>
> 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/20260105-pbl-load-elf-v1-0-e97853f98232@pengutronix.de
>
> ---
> Sascha Hauer (22):
> Makefile.compiler: add objcopy-option
> elf: only accept images matching the native ELF_CLASS
> elf: build for PBL as well
> elf: add elf segment iterator
> 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 vmbarebox build target
> PBL: allow to link ELF image into PBL
> mmu: add MAP_CACHED_RO mapping type
> ARM: drop arm_fixup_vectors()
> ARM: linker script: create separate PT_LOAD segments for text, rodata, and data
> ARM: link ELF image into PBL
> ARM: cleanup barebox proper entry
> ARM: PBL: setup MMU with proper permissions from ELF segments
> riscv: linker script: create separate PT_LOAD segments for text, rodata, and data
> riscv: link ELF image into PBL
> riscv: Allwinner D1: Drop M-Mode
> riscv: add ELF segment-based memory protection with MMU
>
> Makefile | 14 +-
> arch/arm/Kconfig | 1 +
> arch/arm/cpu/exceptions_32.S | 54 +----
> arch/arm/cpu/interrupts_32.c | 5 +-
> arch/arm/cpu/mmu-common.c | 31 ++-
> arch/arm/cpu/mmu-common.h | 3 +-
> arch/arm/cpu/mmu_32.c | 6 +-
> arch/arm/cpu/mmu_64.c | 2 +-
> arch/arm/cpu/no-mmu.c | 2 -
> arch/arm/cpu/start.c | 22 +-
> arch/arm/cpu/uncompress.c | 34 ++-
> arch/arm/include/asm/barebox-arm.h | 4 -
> arch/arm/include/asm/elf.h | 7 +
> arch/arm/lib32/barebox.lds.S | 42 ++--
> arch/arm/lib32/reloc.c | 19 ++
> arch/arm/lib64/barebox.lds.S | 38 ++--
> arch/arm/lib64/reloc.c | 21 +-
> arch/riscv/Kconfig | 18 ++
> arch/riscv/Kconfig.socs | 1 -
> arch/riscv/boot/start.c | 19 +-
> arch/riscv/boot/uncompress.c | 34 ++-
> arch/riscv/cpu/Makefile | 1 +
> arch/riscv/cpu/mmu.c | 354 +++++++++++++++++++++++++++++
> arch/riscv/cpu/mmu.h | 120 ++++++++++
> arch/riscv/include/asm/asm.h | 3 +-
> arch/riscv/include/asm/mmu.h | 36 +++
> arch/riscv/lib/barebox.lds.S | 45 ++--
> arch/riscv/lib/reloc.c | 43 ++--
> common/Makefile | 2 +-
> common/elf.c | 446 +++++++++++++++++++++++++++++++++++--
> include/elf.h | 79 +++++++
> include/mmu.h | 3 +-
> include/pbl/mmu.h | 38 ++++
> pbl/Kconfig | 9 +
> pbl/Makefile | 1 +
> pbl/mmu.c | 107 +++++++++
> scripts/Makefile.compiler | 5 +
> 37 files changed, 1452 insertions(+), 217 deletions(-)
> ---
> base-commit: 2f99ee71fb44dc60b60d234fb38e0b3c6932f02b
> change-id: 20251227-pbl-load-elf-cb4cb0ceb7d8
>
> Best regards,
--
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