| Message ID | 20230520205547.1009254-9-CFSworks@gmail.com |
|---|---|
| State | RFC |
| Delegated to: | Tom Rini |
| Headers | show |
| Series | Improve ARM target's support for LLVM toolchain | expand |
Hi Sam, On Sat, 20 May 2023 at 23:56, Sam Edwards <cfsworks@gmail.com> wrote: > > This is not proper: A .text section is SHT_PROGBITS, > while the .dynamic section is SHT_DYNAMIC. Attempting to > combine them like this creates a section type mismatch. > > It does seem that GNU ld does not complain, but LLVM's lld > considers this an error. > > Signed-off-by: Sam Edwards <CFSworks@gmail.com> > Cc: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> > --- > > arch/arm/lib/elf_aarch64_efi.lds | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm/lib/elf_aarch64_efi.lds b/arch/arm/lib/elf_aarch64_efi.lds > index 5dd9809169..986f13936d 100644 > --- a/arch/arm/lib/elf_aarch64_efi.lds > +++ b/arch/arm/lib/elf_aarch64_efi.lds > @@ -24,10 +24,9 @@ SECTIONS > *(.gnu.linkonce.t.*) > *(.srodata) > *(.rodata*) > - . = ALIGN(16); > - *(.dynamic); > . = ALIGN(512); > } > + .dynamic : { *(.dynamic) } This looks correct. However, this changed recently on commit d7ddeb66a6ce ("efi_loader: fix building aarch64 EFI binaries"). Heinrich any chance you can repeat your tests? Thanks /Ilias > .rela.dyn : { *(.rela.dyn) } > .rela.plt : { *(.rela.plt) } > .rela.got : { *(.rela.got) } > -- > 2.39.2 >
On 5/20/23 22:55, Sam Edwards wrote: > This is not proper: A .text section is SHT_PROGBITS, > while the .dynamic section is SHT_DYNAMIC. Attempting to > combine them like this creates a section type mismatch. > > It does seem that GNU ld does not complain, but LLVM's lld > considers this an error. > > Signed-off-by: Sam Edwards <CFSworks@gmail.com> > Cc: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> > --- > > arch/arm/lib/elf_aarch64_efi.lds | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm/lib/elf_aarch64_efi.lds b/arch/arm/lib/elf_aarch64_efi.lds > index 5dd9809169..986f13936d 100644 > --- a/arch/arm/lib/elf_aarch64_efi.lds > +++ b/arch/arm/lib/elf_aarch64_efi.lds > @@ -24,10 +24,9 @@ SECTIONS > *(.gnu.linkonce.t.*) > *(.srodata) > *(.rodata*) > - . = ALIGN(16); .dynamic should be aligned. Structure Elf64_Dyn requires at least 8 byte alignment. > - *(.dynamic); > . = ALIGN(512); The symbol _etext below should be 512 aligned as in arch/arm/lib/crt0_aarch64_efi.S we have set FileAlignment = 0x200. Best regards Heinrich > } > + .dynamic : { *(.dynamic) } > .rela.dyn : { *(.rela.dyn) } > .rela.plt : { *(.rela.plt) } > .rela.got : { *(.rela.got) }
On 5/22/23 02:10, Heinrich Schuchardt wrote: Hi Heinrich, > .dynamic should be aligned. Structure Elf64_Dyn requires at least 8 byte > alignment. As best as I can tell, linkers (certainly lld[1], apparently also GNU ld judging by its default linker scripts) themselves set the proper word alignment on the .dynamic section that they synthesize for their internal input object. That alignment requirement bubbles up to the output section, so explicit alignment here should not be necessary. > The symbol _etext below should be 512 aligned as in > arch/arm/lib/crt0_aarch64_efi.S we have set FileAlignment = 0x200. Ah, that definitely needs to be fixed since the .rela.* sections might not have the 512 alignment. I've updated my local branch, though this also needs to be addressed in the current master branch. Cheers, Sam [1]: https://github.com/llvm/llvm-project/blob/acce2a315945e386a7be6f014ebe90c2a28f38d9/lld/ELF/SyntheticSections.cpp#L1246
diff --git a/arch/arm/lib/elf_aarch64_efi.lds b/arch/arm/lib/elf_aarch64_efi.lds index 5dd9809169..986f13936d 100644 --- a/arch/arm/lib/elf_aarch64_efi.lds +++ b/arch/arm/lib/elf_aarch64_efi.lds @@ -24,10 +24,9 @@ SECTIONS *(.gnu.linkonce.t.*) *(.srodata) *(.rodata*) - . = ALIGN(16); - *(.dynamic); . = ALIGN(512); } + .dynamic : { *(.dynamic) } .rela.dyn : { *(.rela.dyn) } .rela.plt : { *(.rela.plt) } .rela.got : { *(.rela.got) }
This is not proper: A .text section is SHT_PROGBITS, while the .dynamic section is SHT_DYNAMIC. Attempting to combine them like this creates a section type mismatch. It does seem that GNU ld does not complain, but LLVM's lld considers this an error. Signed-off-by: Sam Edwards <CFSworks@gmail.com> Cc: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> --- arch/arm/lib/elf_aarch64_efi.lds | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)