From 9465c3a9fb557d7ab98b1f2ecd0b8c28c43a8539 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 15 Jun 2021 22:17:01 -0300 Subject: [PATCH] linux: Remove time64-support It breaks the usage case of live migration like CRIU or similar and most usages can be optimized away by either building glibc with a minimum 5.1 kernel or by using the 32-bit syscall for the common case. Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel (with and without --enable-kernel=5.1) and on x86_64-linux-gnu. Reviewed-by: Lukasz Majewski --- sysdeps/unix/sysv/linux/Makefile | 2 +- sysdeps/unix/sysv/linux/time64-support.c | 23 ----------- sysdeps/unix/sysv/linux/time64-support.h | 70 -------------------------------- 3 files changed, 1 insertion(+), 94 deletions(-) delete mode 100644 sysdeps/unix/sysv/linux/time64-support.c delete mode 100644 sysdeps/unix/sysv/linux/time64-support.h diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile index c36ea0e..fd440ef 100644 --- a/sysdeps/unix/sysv/linux/Makefile +++ b/sysdeps/unix/sysv/linux/Makefile @@ -61,7 +61,7 @@ sysdep_routines += adjtimex clone umount umount2 readahead sysctl \ open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \ timerfd_gettime timerfd_settime prctl \ process_vm_readv process_vm_writev clock_adjtime \ - time64-support pselect32 \ + pselect32 \ xstat fxstat lxstat xstat64 fxstat64 lxstat64 \ fxstatat fxstatat64 \ xmknod xmknodat convert_scm_timestamps diff --git a/sysdeps/unix/sysv/linux/time64-support.c b/sysdeps/unix/sysv/linux/time64-support.c deleted file mode 100644 index 0718e74..0000000 --- a/sysdeps/unix/sysv/linux/time64-support.c +++ /dev/null @@ -1,23 +0,0 @@ -/* Auxiliary definitions for 64-bit time_t support. - Copyright (C) 2020-2021 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 - . */ - -#include - -#ifndef __ASSUME_TIME64_SYSCALLS -int __time64_support = 1; -#endif diff --git a/sysdeps/unix/sysv/linux/time64-support.h b/sysdeps/unix/sysv/linux/time64-support.h deleted file mode 100644 index 8466d37..0000000 --- a/sysdeps/unix/sysv/linux/time64-support.h +++ /dev/null @@ -1,70 +0,0 @@ -/* Auxiliary definitions for 64-bit time_t support. - Copyright (C) 2020-2021 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 - . */ - -#include -#include - -/* These helper functions are used to optimize the 64-bit time_t support on - configurations that requires support for 32-bit time_t fallback - (!__ASSUME_TIME64_SYSCALLS). The idea is once the kernel advertises that - it does not have 64-bit time_t support, glibc will stop to try issue the - 64-bit time_t syscall altogether. - - For instance: - - #ifndef __NR_symbol_time64 - # define __NR_symbol_time64 __NR_symbol - #endif - int r; - if (supports_time64 ()) - { - r = INLINE_SYSCALL_CALL (symbol, ...); - if (r == 0 || errno != ENOSYS) - return r; - - mark_time64_unsupported (); - } - #ifndef __ASSUME_TIME64_SYSCALLS - <32-bit fallback syscall> - #endif - return r; - - On configuration with default 64-bit time_t this optimization should be - optimized away by the compiler resulting in no overhead. */ - -#ifndef __ASSUME_TIME64_SYSCALLS -extern int __time64_support attribute_hidden; -#endif - -static inline bool -supports_time64 (void) -{ -#ifdef __ASSUME_TIME64_SYSCALLS - return true; -#else - return atomic_load_relaxed (&__time64_support) != 0; -#endif -} - -static inline void -mark_time64_unsupported (void) -{ -#ifndef __ASSUME_TIME64_SYSCALLS - atomic_store_relaxed (&__time64_support, 0); -#endif -} -- 2.7.4