Re: [PATCH] aarch64: fix elf_machine_dynamic compile error [BZ #29835]

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

The 12/02/2022 11:59, linzhuorong via Libc-alpha wrote:
> elf_machine_dynamic compile error when compiling glibc with --enable-static-pie option turned on, static executables do not have symbol _DYNAMIC

glibc no longer has --enable-static-pie, instead it has
--disable-default-pie .

static pie should have _DYNAMIC symbol since it has dynamic
relocations (relative relocs), what is the binutils version?

maybe glibc should disable default pie if old binutils is
detected.

> 
> Fixes: bca0f5cbc9257c13322b99e55235c4f21ba0bd82("aarch64: Make elf_machine_{load_address,dynamic} robust [BZ #28203]")
> 
> Signed-off-by linzhuorong <linzhuorong@huawei.com>
> ---
>  sysdeps/aarch64/dl-machine.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
> index ae8b14425a..49b1d1ea0e 100644
> --- a/sysdeps/aarch64/dl-machine.h
> +++ b/sysdeps/aarch64/dl-machine.h
> @@ -53,8 +53,9 @@ elf_machine_load_address (void)
>  static inline ElfW(Addr) __attribute__ ((unused))
>  elf_machine_dynamic (void)
>  {
> -  extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
> -  return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address ();
> +  /* Declaring this hidden ensures that a PC-relative reference is uesed.  */
> +  extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
> +  return _GLOBAL_OFFSET_TABLE_[0];
>  }
>  
>  /* Set up the loaded object described by L so its unrelocated PLT
> -- 
> 2.12.3
>