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From: Adhemerval Zanella <azanella@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] linux: Add PR_SET_VMA_ANON_NAME support Date: Tue, 7 Nov 2023 16:41:13 +0000 (GMT) [thread overview] Message-ID: <20231107164113.C052D3858C41@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=78ed8bdf4f13e7f5d8eef77c12fbb030fdbdafe0 commit 78ed8bdf4f13e7f5d8eef77c12fbb030fdbdafe0 Author: Adhemerval Zanella <adhemerval.zanella@linaro.org> Date: Wed Nov 1 09:56:05 2023 -0300 linux: Add PR_SET_VMA_ANON_NAME support 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> Diff: --- include/sys/prctl.h | 5 ++++ sysdeps/generic/setvmaname.h | 27 ++++++++++++++++++++++ sysdeps/unix/sysv/linux/Makefile | 1 + sysdeps/unix/sysv/linux/setvmaname.c | 44 ++++++++++++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/setvmaname.h | 36 +++++++++++++++++++++++++++++ 5 files changed, 113 insertions(+) diff --git a/include/sys/prctl.h b/include/sys/prctl.h index d33f3a290e..8e8e05b07c 100644 --- a/include/sys/prctl.h +++ b/include/sys/prctl.h @@ -3,6 +3,11 @@ # ifndef _ISOMAC +# ifndef PR_SET_VMA +# define PR_SET_VMA 0x53564d41 +# define PR_SET_VMA_ANON_NAME 0 +# endif + extern int __prctl (int __option, ...); libc_hidden_proto (__prctl) 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 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 \ 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> + +/* 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; +} 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
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