[PATCH v3 2/7] support: Add support_set_vma_name

[DJ Delorie]

LGTM
Reviewed-by: DJ Delorie <dj@redhat.com>

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
> diff --git a/support/Makefile b/support/Makefile
> index 917a858bd1..9aa7f23a6e 100644
> --- a/support/Makefile
> +++ b/support/Makefile
> @@ -80,6 +80,7 @@ libsupport-routines = \
>    support_select_modifies_timeout \
>    support_select_normalizes_timeout \
>    support_set_small_thread_stack_size \
> +  support_set_vma_name_supported \
>    support_shared_allocate \
>    support_small_stack_thread_attribute \
>    support_socket_so_timestamp_time64 \
> diff --git a/support/support.h b/support/support.h
> index b7f76bf080..4a068d3aee 100644
> --- a/support/support.h
> +++ b/support/support.h
> @@ -235,6 +235,10 @@ void support_stack_free (struct support_stack *stack);
>     The returned value is the lowest file descriptor number.  */
>  int support_open_dev_null_range (int num, int flags, mode_t mode);
>  
> +
> +/* Check if kernel supports set VMA range name.  */
> +extern bool support_set_vma_name_supported (void);
> +
>  __END_DECLS
>  
>  #endif /* SUPPORT_H */
> diff --git a/support/support_set_vma_name_supported.c b/support/support_set_vma_name_supported.c
> new file mode 100644
> index 0000000000..712caa9b9b
> --- /dev/null
> +++ b/support/support_set_vma_name_supported.c
> @@ -0,0 +1,49 @@
> +/* Check if kernel supports set VMA range name.
> +   Copyright (C) 2023 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 <support/check.h>
> +#include <support/support.h>
> +#include <support/xunistd.h>
> +#include <sys/mman.h>
> +#ifdef __linux__
> +# include <sys/prctl.h>
> +#endif
> +
> +bool
> +support_set_vma_name_supported (void)
> +{
> +#ifdef __linux__
> +  size_t size = sysconf (_SC_PAGESIZE);
> +  if (size == -1)
> +    FAIL_EXIT1 ("sysconf (_SC_PAGESIZE): %m\n");
> +
> +  void *vma = xmmap (0,
> +		     size,
> +		     PROT_NONE,
> +		     MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
> +		     -1);
> +
> +  int r = prctl (PR_SET_VMA, PR_SET_VMA_ANON_NAME, vma, size, "vmaname");
> +
> +  xmunmap (vma, size);
> +
> +  return r == 0;
> +#else
> +  return false;
> +#endif
> +}