From: "Theo de Raadt" <deraadt@openbsd.org>
Subject: Re: Declare _hwcap as hidden
To: Christian Weisgerber <naddy@mips.inka.de>
Cc: tech@openbsd.org
Date: Sat, 09 May 2026 06:54:37 -0600

Agree.

Christian Weisgerber <naddy@mips.inka.de> wrote:

> I think this was forgotten when elf_aux_info() was added.  The _hwcap
> variables are only used inside libc, so they should be declared hidden.
> We can just add the declarations to hidden/sys/auxv.h.
> 
> Before:
> $ readelf -s obj/libc.so.103.0| fgrep _hwcap
>   4063: 00000000001051c8     4 OBJECT  LOCAL  DEFAULT   23 _hwcap_avail
>   4064: 00000000001051c0     8 OBJECT  LOCAL  DEFAULT   23 _hwcap
>   4065: 00000000001051d8     4 OBJECT  LOCAL  DEFAULT   23 _hwcap2_avail
>   4066: 00000000001051d0     8 OBJECT  LOCAL  DEFAULT   23 _hwcap2
> 
> After:
> $ readelf -s obj/libc.so.103.0| fgrep _hwcap
>   1784: 0000000000100880     8 OBJECT  LOCAL  HIDDEN    23 _hwcap
>   1785: 0000000000100888     4 OBJECT  LOCAL  HIDDEN    23 _hwcap_avail
>   1786: 0000000000100890     8 OBJECT  LOCAL  HIDDEN    23 _hwcap2
>   1787: 0000000000100898     4 OBJECT  LOCAL  HIDDEN    23 _hwcap2_avail
> 
> OK?
> 
> -----------------------------------------------
> commit e030561035c15c903f1e6b0a1feacb5492867a7b (hwcap)
> from: Christian Weisgerber <naddy@mips.inka.de>
> date: Sat May  9 12:38:40 2026 UTC
>  
>  declare _hwcap and related variables as hidden
>  
> diff dfc436a2a7e14a48b9213e241b55d30d94477a54 e030561035c15c903f1e6b0a1feacb5492867a7b
> commit - dfc436a2a7e14a48b9213e241b55d30d94477a54
> commit + e030561035c15c903f1e6b0a1feacb5492867a7b
> blob - dd2cd9f40451841c3fe7b8ae2dd9274b1551c959
> blob + e57f9dcb277fd79922c7c82744bb5e326da436cf
> --- lib/libc/dlfcn/init.c
> +++ lib/libc/dlfcn/init.c
> @@ -21,6 +21,7 @@
>  #include <sys/types.h>
>  #include <sys/syscall.h>
>  #include <sys/timetc.h>		/* timekeep */
> +#include <sys/auxv.h>		/* _hwcap */
>  
>  #ifndef PIC
>  #include <sys/mman.h>
> blob - a4b7667ba6fd0d1c9056e2e645d2a637e8a51790
> blob + c9852bc4ca467710893631f61e11098c5ecc2b44
> --- lib/libc/gen/elf_aux_info.c
> +++ lib/libc/gen/elf_aux_info.c
> @@ -20,11 +20,8 @@
>  #include <sys/auxv.h>
>  
>  #include <errno.h>
> +#include <unistd.h>
>  
> -extern int _pagesize;
> -extern unsigned long _hwcap, _hwcap2;
> -extern int _hwcap_avail, _hwcap2_avail;
> -
>  int
>  elf_aux_info(int request, void *buf, int buflen)
>  {
> blob - cd566b7b2a21edc0421c3ef7063a8fca20fa635b
> blob + 07eec4dcd49a65521acc6daefd1a127a833378b6
> --- lib/libc/hidden/sys/auxv.h
> +++ lib/libc/hidden/sys/auxv.h
> @@ -21,6 +21,11 @@
>  
>  #include_next <sys/auxv.h>
>  
> +__BEGIN_HIDDEN_DECLS
> +extern unsigned long	_hwcap, _hwcap2;
> +extern int	_hwcap_avail, _hwcap2_avail;
> +__END_HIDDEN_DECLS
> +
>  PROTO_DEPRECATED(elf_aux_info);
>  
>  #endif /* !_LIBC_SYS_AUXV_H_ */
> 
> 
> -- 
> Christian "naddy" Weisgerber                          naddy@mips.inka.de
>