From dba950e3174a5210b900a26a7d2f361cadea2834 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Mon, 29 Jun 2020 13:35:50 -0300 Subject: sysv: linux: Add 64-bit time_t variant for semctl Different than others 64-bit time_t syscalls, the SysIPC interface does not provide a new set of syscall for y2038 safeness. Instead it uses unused fields in semid_ds structure to return the high bits for the timestamps. To provide a y2038 safe interface a new symbol __semctl64 is added and __semctl is change to call it instead (it adds some extra buffer copying for the 32 bit time_t implementation). Two new structures are added: 1. kernel_semid64_ds: used internally only on 32-bit architectures to issue the syscall. A handful of architectures (hppa, i386, mips, powerpc32, sparc32) require specific implementations due their kernel ABI. 2. semid_ds64: this is only for __TIMESIZE != 64 to use along with the 64-bit semctl. It is different than the kernel struct because the exported 64-bit time_t might require different alignment depending on the architecture ABI. So the resulting implementation does: 1. For 64-bit architectures it assumes semid_ds already contains 64-bit time_t fields and will result in just the __semctl symbol using the __semctl64 code. The semid_ds argument is passed as-is to the syscall. 2. For 32-bit architectures with default 64-bit time_t (newer ABIs such riscv32 or arc), it will also result in only one exported symbol but with the required high/low handling. It might be possible to optimize it further to avoid the kernel_semid64_ds to semun transformation if the exported ABI for the architectures matches the expected kernel ABI, but the implementation is already complex enough and don't think this should be a hotspot in any case. 3. Finally for 32-bit architecture with both 32-bit and 64-bit time_t support we follow the already set way to provide one symbol with 64-bit time_t support and implement the 32-bit time_t support using the 64-bit one. The default 32-bit symbol will allocate and copy the semid_ds over multiple buffers, but this should be deprecated in favor of the __semctl64 anyway. Checked on i686-linux-gnu and x86_64-linux-gnu. I also did some sniff tests on powerpc, powerpc64, mips, mips64, armhf, sparcv9, and sparc64. Reviewed-by: Alistair Francis Tested-by: Alistair Francis Tested-by: Vineet Gupta Reviewed-by: Carlos O'Donell Tested-by: Carlos O'Donell --- .../unix/sysv/linux/bits/types/struct_semid64_ds.h | 33 ++++++++++++++++++++++ .../unix/sysv/linux/bits/types/struct_semid_ds.h | 21 +++++--------- 2 files changed, 40 insertions(+), 14 deletions(-) create mode 100644 sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h (limited to 'sysdeps/unix/sysv/linux/bits') diff --git a/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h b/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h new file mode 100644 index 0000000000..bda9eb4469 --- /dev/null +++ b/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h @@ -0,0 +1,33 @@ +/* Generic implementation of the semaphore struct semid64_ds. + Copyright (C) 2020 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 + . */ + +#ifndef _SYS_SEM_H +# error "Never include directly; use instead." +#endif + +#if __TIMESIZE == 64 +# define __semid64_ds semid_ds +#else +struct __semid64_ds +{ + struct ipc_perm sem_perm; /* operation permission struct */ + __time64_t sem_otime; /* last semop() time */ + __time64_t sem_ctime; /* last time changed by semctl() */ + __syscall_ulong_t sem_nsems; /* number of semaphores in set */ +}; +#endif diff --git a/sysdeps/unix/sysv/linux/bits/types/struct_semid_ds.h b/sysdeps/unix/sysv/linux/bits/types/struct_semid_ds.h index 4222e6a59f..bc26d8be08 100644 --- a/sysdeps/unix/sysv/linux/bits/types/struct_semid_ds.h +++ b/sysdeps/unix/sysv/linux/bits/types/struct_semid_ds.h @@ -21,26 +21,19 @@ #endif /* Data structure describing a set of semaphores. */ -#if __TIMESIZE == 32 struct semid_ds { struct ipc_perm sem_perm; /* operation permission struct */ +#if __TIMESIZE == 32 __time_t sem_otime; /* last semop() time */ - __syscall_ulong_t __glibc_reserved1; + __syscall_ulong_t __sem_otime_high; __time_t sem_ctime; /* last time changed by semctl() */ - __syscall_ulong_t __glibc_reserved2; - __syscall_ulong_t sem_nsems; /* number of semaphores in set */ - __syscall_ulong_t __glibc_reserved3; - __syscall_ulong_t __glibc_reserved4; -}; + __syscall_ulong_t __sem_ctime_high; #else -struct semid_ds -{ - struct ipc_perm sem_perm; /* operation permission struct */ - __time_t sem_otime; /* last semop() time */ - __time_t sem_ctime; /* last time changed by semctl() */ - __syscall_ulong_t sem_nsems; /* number of semaphores in set */ + __time_t sem_otime; + __time_t sem_ctime; +#endif + __syscall_ulong_t sem_nsems; /* number of semaphores in set */ __syscall_ulong_t __glibc_reserved3; __syscall_ulong_t __glibc_reserved4; }; -#endif -- cgit 1.4.1