Re: [PATCH v2 1/7] linux: Add PR_SET_VMA_ANON_NAME support

[DJ Delorie <dj@redhat.com>]

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

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
>  
>  # ifndef _ISOMAC
>  
> +#  ifndef PR_SET_VMA
> +#   define PR_SET_VMA            0x53564d41
> +#   define PR_SET_VMA_ANON_NAME  0
> +#  endif
> +

These match the kernel includes on rawhide, so OK.

> diff --git a/sysdeps/generic/setvmaname.h b/sysdeps/generic/setvmaname.h
> new file mode 100644
> index 0000000000..2824587e9f
> --- /dev/null
> +++ b/sysdeps/generic/setvmaname.h
> @@ -0,0 +1,27 @@
> +/* Utilities functions to name memory mappings.
> +   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/>.  */
> +
> +#ifndef __SETVMANAME_H
> +#define __SETVMANAME_H
> +
> +static inline
> +void __set_vma_name (void *start, size_t len, const char *name)
> +{
> +}
> +
> +#endif

Ok.

> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 063719bae6..250df6f455 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -97,6 +97,7 @@ sysdep_routines += \
>    readahead \
>    setfsgid \
>    setfsuid \
> +  setvmaname \
>    signalfd \
>    splice \
>    sysctl \

Ok.

> diff --git a/sysdeps/unix/sysv/linux/setvmaname.c b/sysdeps/unix/sysv/linux/setvmaname.c
> new file mode 100644
> index 0000000000..9960ab5917
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/setvmaname.c
> @@ -0,0 +1,44 @@
> +/* Utilities functions to name memory mappings.
> +   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 <ldsodefs.h>
> +#include <setvmaname.h>
> +#include <sys/prctl.h>
> +#include <sysdep.h>

Ok.

> +/* If PR_SET_VMA_ANON_NAME is not supported by the kernel, prctl returns
> +   EINVAL.  However, it also returns the same error for invalid argument.
> +   Since it is an internal-only API, it assumes well formatted input:
> +   aligned START, with (START, START+LEN) being a valid memory range,
> +   and NAME with a limit of 80 characters without invalid one ("\\`$[]").  */
> +
> +void
> +__set_vma_name (void *start, size_t len, const char *name)
> +{
> +  static int prctl_supported = 1;
> +  if (atomic_load_relaxed (&prctl_supported) == 0)
> +    return;
> +
> +  int r = INTERNAL_SYSCALL_CALL (prctl, PR_SET_VMA, PR_SET_VMA_ANON_NAME,
> +				 start, len, name);
> +  if (r == 0 || r != -EINVAL)
> +    return;

I'll point out that this logic is redundant, but I like that it conveys
more meaning this way :-)

Ok.

> +  atomic_store_relaxed (&prctl_supported, 0);
> +  return;
> +}

Ok.

> diff --git a/sysdeps/unix/sysv/linux/setvmaname.h b/sysdeps/unix/sysv/linux/setvmaname.h
> new file mode 100644
> index 0000000000..eaa7a7a32e
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/setvmaname.h
> @@ -0,0 +1,36 @@
> +/* Utilities functions to name memory mappings.
> +   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/>.  */
> +
> +#ifndef __SETVMANAME_H
> +#define __SETVMANAME_H
> +
> +/* Set the NAME to the anonymous memory map START with size of LEN.
> +   It assumes well-formatted input.  */
> +#if IS_IN(libc) || IS_IN(rtld)
> +void __set_vma_name (void *start, size_t len, const char *name)
> +  attribute_hidden;
> +#else
> +#include <sys/prctl.h>
> +
> +static inline void __set_vma_name (void *start, size_t len, const char *name)
> +{
> +  prctl (PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, name);
> +}
> +#endif
> +
> +#endif

Ok.