Am 6. November 2022 19:36:15 MEZ schrieb Patrick Zacharias <littlefighte...@web.de>: >I created a GitHub repository demonstrating the issue, together with >instructions on how to build it. > >https://github.com/Fighter19/hello-world-arm-efi
Please, check the instructions in https://doc.rust-lang.org/rustc/platform-support/unknown-uefi.html Best regards Heinrich > >Currently, when using the old linker file, it will crash. >Personally, to test it, I built U-Boot for QEMU and loaded the EFI file via >TFTP. > >Am 06.11.22 um 18:03 schrieb Patrick Zacharias: >> Hi Heinrich, >> >> Thanks for the information, I'll make sure to use it for future >> contributions. >> >> I encountered this issue, while building a custom EFI application using Rust >> by linking >> the following files: >> >> ./arch/arm/lib/reloc_arm_efi.c >> ./arch/arm/lib/crt0_arm_efi.S >> ./arch/arm/lib/elf_arm_efi.lds >> >> As well as the custom application built as a library, that exports >> "efi_main". >> >> Thus, the relocations were caused by the "write_fmt" functions that Rust >> provides. >> I encountered it, when concatenating two strings. >> format!("Test {}", "Test2"); >> >> The relocation was not applied and therefor lead to a crash. >> >> From my understanding these relocations are ELF relocations and are therefor >> applied by the _relocate function (inside the built application) >> and not by the EFI loader. This is why I assumed, that it's fine for these >> relocations to reside in the data section. >> >> I noticed, that in the _relocate function in ./arch/arm/lib/reloc_arm_efi.c, >> that the case R_ARM_RELATIVE was never entered, >> even though the generated shared object included them. >> I then looked at the EFI header file (crt0_arm_efi.S) and noticed, that it >> specifies only up to _edata to be loaded. >> >> I concluded that _edata needs to be extended to include the ELF relocations >> as well. >> >> After I decided to place it after the relocations, I noticed, that _edata is >> already specified at the same (new position) in gnu-efi. >> This reaffirmed me to contribute the patch as it currently is. >> >> I assumed, that on x86, that the linker treats the ELF relocations (.rela.*) >> as if it was part of the data section. >> From my understanding the EFI relocations are in .reloc while the ELF >> relocations are in .rela.*. >> I might be mistaken, however. >> >> Greetings, >> Patrick >> >> Am 06.11.22 um 10:20 schrieb Heinrich Schuchardt: >>> On 10/31/22 21:01, Patrick Zacharias wrote: >>>> Prior to this commit, the relocations would not get loaded by the efi >>>> loader. >>>> >>>> This lead to none of the relocations being applied. >>>> >>>> Signed-off-by: Fighter19 <1475802+fighte...@users.noreply.github.com> >>> >>> Thanks Patrick for your contribution. >>> >>> You can use scripts/get_maintainer.pl to determine to whom a patch >>> should be sent. >>> >>> Where did you actually see relocations? >>> Which code is not position independent? >>> >>>> --- >>>> arch/arm/lib/elf_aarch64_efi.lds | 2 +- >>>> arch/arm/lib/elf_arm_efi.lds | 2 +- >>>> 2 files changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/arch/arm/lib/elf_aarch64_efi.lds >>>> b/arch/arm/lib/elf_aarch64_efi.lds >>>> index c0604dad46..1982864d17 100644 >>>> --- a/arch/arm/lib/elf_aarch64_efi.lds >>>> +++ b/arch/arm/lib/elf_aarch64_efi.lds >>>> @@ -46,12 +46,12 @@ SECTIONS >>>> *(COMMON) >>>> . = ALIGN(512); >>>> _bss_end = .; >>>> - _edata = .; >>>> } >>>> .rela.dyn : { *(.rela.dyn) } >>>> .rela.plt : { *(.rela.plt) } >>>> .rela.got : { *(.rela.got) } >>>> .rela.data : { *(.rela.data) *(.rela.data*) } >>>> + _edata = .; >>>> _data_size = . - _etext; >>>> >>>> . = ALIGN(4096); >>>> diff --git a/arch/arm/lib/elf_arm_efi.lds b/arch/arm/lib/elf_arm_efi.lds >>>> index 767ebda635..c1b58a8033 100644 >>>> --- a/arch/arm/lib/elf_arm_efi.lds >>>> +++ b/arch/arm/lib/elf_arm_efi.lds >>>> @@ -46,12 +46,12 @@ SECTIONS >>>> *(COMMON) >>>> . = ALIGN(512); >>>> _bss_end = .; >>>> - _edata = .; >>>> } >>>> .rel.dyn : { *(.rel.dyn) } >>>> .rel.plt : { *(.rel.plt) } >>>> .rel.got : { *(.rel.got) } >>>> .rel.data : { *(.rel.data) *(.rel.data*) } >>>> + _edata = .; >>> >>> Relocations (if they exist) should be in the .reloc section, not in the >>> .data section. >>> >>> If we want to create a .reloc section, we have to change >>> arch/arm/lib/crt0_*_efi.S too. Furthermore the relocation section must >>> be pointed to by field BaseRelocationTable of the Optional Header Data >>> Directories (see PE-COFF specification). >>> >>> Please, consider the other UEFI architectures (x86 and RISC-V) too. >>> >>> Best regards >>> >>> Heinrich >>> >>>> _data_size = . - _etext; >>>> >>>> /DISCARD/ : { >>> >
