[Bug binutils/21725] [2.29 Regression] binutils fails to build glibc-2.24 on aarch64-linux-gnu and arm-linux-gnueabihf

[jiwang at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=21725

--- Comment #9 from Jiong Wang <jiwang at gcc dot gnu.org> ---
(In reply to Jiong Wang from comment #8)
> sysdeps/arm/dl-machine.h:
> 
> elf_machine_load_address (void)
>    extern Elf32_Addr internal_function __dl_start (void *) asm ("_dl_start");
>    Elf32_Addr got_addr = (Elf32_Addr) &__dl_start;
>    Elf32_Addr pcrel_addr;
> #ifdef __thumb__
>   /* Clear the low bit of the funciton address.  */
>   got_addr &= ~(Elf32_Addr) 1;
> #endif
>    asm ("adr %0, _dl_start" : "=r" (pcrel_addr));
>    return pcrel_addr - got_addr;
> 
> The __thumb__ hunk is suspicious, as Nick's patch will also update the low
> bit.
> 
> If I remove the "#ifdef __thumb__", the generated ld.so will also work.

I think GLIBC ought to be fixed there to be more portable, the __thumb__ can be
kept, but pcrel_addr should always be strippted as well if it's __thumb__.  As
the assumption of PC-rel relocation finished within assembler does not touch
bit0 does not holds after Nick's fix.

I will post a GLIBC fix.

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