y2038: allow disabling time32 system calls (942437c9) · Commits · 戴 / test

At the moment, the compilation of the old time32 system calls depends purely on the architecture. As systems with new libc based on 64-bit time_t are getting deployed, even architectures that previously supported these (notably x86-32 and arm32 but also many others) no longer depend on them, and removing them from a kernel image results in a smaller kernel binary, the same way we can leave out many other optional system calls. More importantly, on an embedded system that needs to keep working beyond year 2038, any user space program calling these system calls is likely a bug, so removing them from the kernel image does provide an extra debugging help for finding broken applications. I've gone back and forth on hiding this option unless CONFIG_EXPERT is set. This version leaves it visible based on the logic that eventually it will be turned off indefinitely. Acked-by:

Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by:

Arnd Bergmann <arnd@arndb.de>

arch/Kconfig

+2 −1

Original line number	Diff line number	Diff line
		@@ -797,7 +797,8 @@ config COMPAT_OLD_SIGACTION
		bool

		config COMPAT_32BIT_TIME
		def_bool !64BIT \|\| COMPAT
		bool "Provide system calls for 32-bit time_t"
		default !64BIT \|\| COMPAT
		help
		This enables 32 bit time_t support in addition to 64 bit time_t support.
		This is relevant on all 32-bit architectures, and 64-bit architectures

kernel/sys_ni.c

+23 −0

Original line number	Diff line number	Diff line
		@@ -410,6 +410,29 @@ COND_SYSCALL(send);
		COND_SYSCALL(bdflush);
		COND_SYSCALL(uselib);

		/* optional: time32 */
		COND_SYSCALL(time32);
		COND_SYSCALL(stime32);
		COND_SYSCALL(utime32);
		COND_SYSCALL(adjtimex_time32);
		COND_SYSCALL(sched_rr_get_interval_time32);
		COND_SYSCALL(nanosleep_time32);
		COND_SYSCALL(rt_sigtimedwait_time32);
		COND_SYSCALL_COMPAT(rt_sigtimedwait_time32);
		COND_SYSCALL(timer_settime32);
		COND_SYSCALL(timer_gettime32);
		COND_SYSCALL(clock_settime32);
		COND_SYSCALL(clock_gettime32);
		COND_SYSCALL(clock_getres_time32);
		COND_SYSCALL(clock_nanosleep_time32);
		COND_SYSCALL(utimes_time32);
		COND_SYSCALL(futimesat_time32);
		COND_SYSCALL(pselect6_time32);
		COND_SYSCALL_COMPAT(pselect6_time32);
		COND_SYSCALL(ppoll_time32);
		COND_SYSCALL_COMPAT(ppoll_time32);
		COND_SYSCALL(utimensat_time32);
		COND_SYSCALL(clock_adjtime32);

		/*
		* The syscalls below are not found in include/uapi/asm-generic/unistd.h

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