Re: [PATCH 2/3] elf: Introduce GLRO (dl_libc_freeres), called from __libc_freeres

[Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>]

Maybe add a comment why this is will be used.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

On 03/11/2021 13:27, Florian Weimer via Gcc-patches wrote:
> ---
>  elf/Makefile               |  2 +-
>  elf/dl-libc_freeres.c      | 24 ++++++++++++++++++++++++
>  elf/rtld.c                 |  1 +
>  malloc/set-freeres.c       |  5 +++++
>  sysdeps/generic/ldsodefs.h |  7 +++++++
>  5 files changed, 38 insertions(+), 1 deletion(-)
>  create mode 100644 elf/dl-libc_freeres.c
> 
> diff --git a/elf/Makefile b/elf/Makefile
> index cb9bcfb799..1c768bdf47 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -68,7 +68,7 @@ elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \
>  rtld-routines	= rtld $(all-dl-routines) dl-sysdep dl-environ dl-minimal \
>    dl-error-minimal dl-conflict dl-hwcaps dl-hwcaps_split dl-hwcaps-subdirs \
>    dl-usage dl-diagnostics dl-diagnostics-kernel dl-diagnostics-cpu \
> -  dl-mutex
> +  dl-mutex dl-libc_freeres
>  all-rtld-routines = $(rtld-routines) $(sysdep-rtld-routines)
>  
>  CFLAGS-dl-runtime.c += -fexceptions -fasynchronous-unwind-tables

Ok.

> diff --git a/elf/dl-libc_freeres.c b/elf/dl-libc_freeres.c
> new file mode 100644
> index 0000000000..68f305a6f9
> --- /dev/null
> +++ b/elf/dl-libc_freeres.c
> @@ -0,0 +1,24 @@
> +/* Deallocating malloc'ed memory from the dynamic loader.
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <ldsodefs.h>
> +
> +void
> +__rtld_libc_freeres (void)
> +{
> +}

Ok.

> diff --git a/elf/rtld.c b/elf/rtld.c
> index be2d5d8e74..847141e21d 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -378,6 +378,7 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
>      ._dl_catch_error = _rtld_catch_error,
>      ._dl_error_free = _dl_error_free,
>      ._dl_tls_get_addr_soft = _dl_tls_get_addr_soft,
> +    ._dl_libc_freeres = __rtld_libc_freeres,
>  #ifdef HAVE_DL_DISCOVER_OSVERSION
>      ._dl_discover_osversion = _dl_discover_osversion
>  #endif

Ok.

> diff --git a/malloc/set-freeres.c b/malloc/set-freeres.c
> index 5c19a2725c..856ff7831f 100644
> --- a/malloc/set-freeres.c
> +++ b/malloc/set-freeres.c
> @@ -21,6 +21,7 @@
>  #include <libc-internal.h>
>  #include <unwind-link.h>
>  #include <dlfcn/dlerror.h>
> +#include <ldsodefs.h>
>  
>  #include "../nss/nsswitch.h"
>  #include "../libio/libioP.h"
> @@ -67,6 +68,10 @@ __libc_freeres (void)
>  
>        call_function_static_weak (__libc_dlerror_result_free);
>  
> +#ifdef SHARED
> +      GLRO (dl_libc_freeres) ();
> +#endif
> +
>        for (p = symbol_set_first_element (__libc_freeres_ptrs);
>             !symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
>          free (*p);

OK.

> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 1318c36dce..c26860430c 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -712,6 +712,10 @@ struct rtld_global_ro
>       namespace.  */
>    void (*_dl_error_free) (void *);
>    void *(*_dl_tls_get_addr_soft) (struct link_map *);
> +
> +  /* Called from __libc_shared to deallocate malloc'ed memory.  */
> +  void (*_dl_libc_freeres) (void);
> +
>  #ifdef HAVE_DL_DISCOVER_OSVERSION
>    int (*_dl_discover_osversion) (void);
>  #endif
> @@ -1416,6 +1420,9 @@ __rtld_mutex_init (void)
>  }
>  #endif /* !PTHREAD_IN_LIBC */
>  
> +/* Implementation of GL (dl_libc_freeres).  */
> +void __rtld_libc_freeres (void) attribute_hidden;
> +
>  void __thread_gscope_wait (void) attribute_hidden;
>  # define THREAD_GSCOPE_WAIT() __thread_gscope_wait ()
>  
> 

OK.