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* [glibc] linux: Add PR_SET_VMA_ANON_NAME support
@ 2023-11-07 16:41 Adhemerval Zanella
0 siblings, 0 replies; only message in thread
From: Adhemerval Zanella @ 2023-11-07 16:41 UTC (permalink / raw)
To: glibc-cvs
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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