[PATCH v10 4/4] elf: Fix runtime linker auditing on aarch64 (BZ #26643)

[Szabolcs Nagy]

The 01/17/2022 18:31, Adhemerval Zanella via Libc-alpha wrote:
> From: Ben Woodard <woodard@redhat.com>
> 
> The rtld audit support show two problems on aarch64:
> 
>   1. _dl_runtime_resolve does not preserve x8, the indirect result
>       location register, which might generate wrong result calls
>       depending of the function signature.
> 
>   2. The NEON Q registers pushed onto the stack by _dl_runtime_resolve
>      were twice the size of D registers extracted from the stack frame by
>      _dl_runtime_profile.
> 
> While 2. might result in wrong information passed on the PLT tracing,
> 1. generates wrong runtime behaviour.
> 
> The aarch64 rtld audit support is change to:
> 
>   * Both La_aarch64_regs and La_aarch64_retval are expanded to include
>     both x8 and the full sized NEON V registers, as defined by the
>     ABI.
> 
>   * dl_runtime_profile needed to extract registers saved by
>     _dl_runtime_resolve and put them into the new correctly sized
>     La_aarch64_regs structure.
> 
>   * The LAV_CURRENT check is change to only accept new audit modules
>     to avoid the undefined behavior of not save/restore x8.
> 
>   * Different than other architectures, audit modules older than
>     LAV_CURRENT are rejected (both La_aarch64_regs and La_aarch64_retval
>     changed their layout and the it does worth the to support multiple
>     audit interface with the inherent aarch64 issues).
> 
>   * A new field is also reserved on both La_aarch64_regs and
>     La_aarch64_retval to support variant pcs symbols.
> 
> Similar to x86, a new La_aarch64_vector type to represent the NEON
> register is added on the La_aarch64_regs (so each type can be accessed
> directly).
> 
> Since LAV_CURRENT was already bumped to support bind-now, there is
> no need to increase it again.
> 
> Checked on aarch64-linux-gnu.
> 
> Co-authored-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Please update the copyright years in new files.
With that fixed this looks good to me.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>