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 --- sysdeps/unix/sysv/linux/i386/struct_kernel_semid64_ds.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) create mode 100644 sysdeps/unix/sysv/linux/i386/struct_kernel_semid64_ds.h (limited to 'sysdeps/unix/sysv/linux/i386') diff --git a/sysdeps/unix/sysv/linux/i386/struct_kernel_semid64_ds.h b/sysdeps/unix/sysv/linux/i386/struct_kernel_semid64_ds.h new file mode 100644 index 0000000000..bab9cf63ba --- /dev/null +++ b/sysdeps/unix/sysv/linux/i386/struct_kernel_semid64_ds.h @@ -0,0 +1,12 @@ +/* Analogous to kernel struct semid64_ds used on semctl. */ +struct kernel_semid64_ds +{ + struct ipc_perm sem_perm; + unsigned long sem_otime; + unsigned long sem_otime_high; + unsigned long sem_ctime; + unsigned long sem_ctime_high; + __syscall_ulong_t sem_nsems; + __syscall_ulong_t __unused3; + __syscall_ulong_t __unused4; +}; -- cgit 1.4.1