elf: Add CPU iteration support for future use in ld.so diagnostics

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

2 files changed, 100 insertions, 0 deletions

diff --git a/sysdeps/generic/dl-affinity.h b/sysdeps/generic/dl-affinity.h
new file mode 100644
index 0000000000..d117f737e9
--- /dev/null
+++ b/sysdeps/generic/dl-affinity.h
@@ -0,0 +1,54 @@
+/* CPU affinity handling for the dynamic linker.  Stub version.
+   Copyright (C) 2024 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 DL_AFFINITY_H
+#define DL_AFFINITY_H
+
+#include <errno.h>
+#include <stddef.h>
+
+/* On success, write the current CPU ID to *CPU, and the current node
+   ID to *NODE, and return 0.  Return a negative error code on
+   failure.  */
+static inline int
+_dl_getcpu (unsigned int *cpu, unsigned int *node)
+{
+  return -ENOSYS;
+}
+
+/* On success, write CPU ID affinity bits for the current thread to
+   *BITS, which must be SIZE bytes long, and return the number of
+   bytes updated, a multiple of sizeof (unsigned long int).  On
+   failure, return a negative error code.  */
+static int
+_dl_getaffinity (unsigned long int *bits, size_t size)
+{
+  return -ENOSYS;
+}
+
+/* Set the CPU affinity mask for the current thread to *BITS, using
+   the SIZE bytes from that array, which should be a multiple of
+   sizeof (unsigned long int).  Return 0 on success, and a negative
+   error code on failure.  */
+static int
+_dl_setaffinity (const unsigned long int *bits, size_t size)
+{
+  return -ENOSYS;
+}
+
+#endif /* DL_AFFINITY_H */
diff --git a/sysdeps/unix/sysv/linux/dl-affinity.h b/sysdeps/unix/sysv/linux/dl-affinity.h
new file mode 100644
index 0000000000..bbfede7750
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-affinity.h
@@ -0,0 +1,46 @@
+/* CPU affinity handling for the dynamic linker.  Linux version.
+   Copyright (C) 2024 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/>.  */
+
+/* See sysdeps/generic/dl-affinity.h for documentation of these interfaces.  */
+
+#ifndef DL_AFFINITY_H
+#define DL_AFFINITY_H
+
+#include <sysdep.h>
+#include <stddef.h>
+#include <unistd.h>
+
+static inline int
+_dl_getcpu (unsigned int *cpu, unsigned int *node)
+{
+  return INTERNAL_SYSCALL_CALL (getcpu, cpu, node);
+}
+
+static int
+_dl_getaffinity (unsigned long int *bits, size_t size)
+{
+  return INTERNAL_SYSCALL_CALL (sched_getaffinity, /* TID */ 0, size, bits);
+}
+
+static int
+_dl_setaffinity (const unsigned long int *bits, size_t size)
+{
+  return INTERNAL_SYSCALL_CALL (sched_setaffinity, /* TID */ 0, size, bits);
+}
+
+#endif /* DL_AFFINITY_H */