Re: [PATCH] powerpc: Use FLAG_ELF_LIBC6 for 32-bit known libraries

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 04/11/2021 15:10, Lucas A. M. Magalhaes via Libc-alpha wrote:
> In systems with more versions of the known libraries, i.e. on IBM
> Advance Toolchain, ldconfig will order them incorrectly on ld.cache.
> 
> The issue only occurs with 32-bit libraries that don't depend on libc or
> libm. That's because process_elf32_file check if the elf depends on one
> of the libraries at known_libs to select the elf flag. For example, as
> libc.so.6 don't depend on itself or on libm it will be flagged as
> FLAG_ELF instead of FLAG_ELF_LIBC6 as expected.

Wouldn't be simpler to check if the DT_SONAME matches any on 'known_libs' after
dynamic section parsing and set the appropriated flag on generic 'process_file'? 

(also powerpc SYSDEP_KNOWN_LIBRARY_NAMES seems redundant).

> 
> This commit fixes this by checking if a appropriate flag was set by
> process_elf32_file. If not it will search on known_libs and use the flag
> in there.
> ---
>  sysdeps/unix/sysv/linux/powerpc/readelflib.c | 21 +++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/powerpc/readelflib.c b/sysdeps/unix/sysv/linux/powerpc/readelflib.c
> index 51f8a9496a..94da21c407 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/readelflib.c
> +++ b/sysdeps/unix/sysv/linux/powerpc/readelflib.c
> @@ -33,11 +33,26 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
>  		  char **soname, void *file_contents, size_t file_length)
>  {
>    ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
> -  int ret;
> +  int ret, j;
>  
>    if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
> -    return process_elf32_file (file_name, lib, flag, osversion, isa_level,
> -			       soname, file_contents, file_length);
> +    {
> +      ret = process_elf32_file (file_name, lib, flag, osversion, isa_level,
> +                                soname, file_contents, file_length);
> +      /* Use the apropriate flag for known_libs instead of FLAG_ELF.  */
> +      if (*flag == FLAG_ELF)
> +        {
> +          for (j = 0;
> +               j < sizeof (known_libs) / sizeof (known_libs [0]);
> +               ++j)
> +            if (strcmp (lib, known_libs [j].soname) == 0)
> +              {
> +                *flag = known_libs [j].flag;
> +                break;
> +              }
> +        }
> +      return ret;
> +    }
>    else
>      {
>        ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
>