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linux: Add PR_SET_VMA_ANON_NAME support

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Linux 5.17 added support to naming anonymous virtual memory areas
through the prctl syscall.  The __set_vma_name is a wrapper to avoid
optimizing the prctl call if the kernel does not support it.

If the kernel does not support PR_SET_VMA_ANON_NAME, prctl returns
EINVAL. And it also returns the same error for an 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 an invalid one
("\\`$[]").
Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Adhemerval Zanella 2023-11-01 09:56:05 -03:00
parent 091ee2190d
commit 78ed8bdf4f
5 changed files with 113 additions and 0 deletions
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5
include/sys/prctl.h
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@ -3,6 +3,11 @@
# ifndef _ISOMAC # ifndef _ISOMAC
# ifndef PR_SET_VMA
# define PR_SET_VMA 0x53564d41
# define PR_SET_VMA_ANON_NAME 0
# endif
extern int __prctl (int __option, ...); extern int __prctl (int __option, ...);
libc_hidden_proto (__prctl) libc_hidden_proto (__prctl)

27
sysdeps/generic/setvmaname.h Normal file
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@ -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

1
sysdeps/unix/sysv/linux/Makefile
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@ -97,6 +97,7 @@ sysdep_routines += \
readahead \ readahead \
setfsgid \ setfsgid \
setfsuid \ setfsuid \
setvmaname \
signalfd \ signalfd \
splice \ splice \
sysctl \ sysctl \

44
sysdeps/unix/sysv/linux/setvmaname.c Normal file
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@ -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>
/* 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;
atomic_store_relaxed (&prctl_supported, 0);
return;
}

36
sysdeps/unix/sysv/linux/setvmaname.h Normal file
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@ -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