Commit 2c622148 authored by Tony Breeds's avatar Tony Breeds Committed by Linus Torvalds
Browse files

Fix discrepancy between VDSO based gettimeofday() and sys_gettimeofday(). 



On platforms that copy sys_tz into the vdso (currently only x86_64, soon to
include powerpc), it is possible for the vdso to get out of sync if a user
calls (admittedly unusual) settimeofday(NULL, ptr).

This patch adds a hook for architectures that set
CONFIG_GENERIC_TIME_VSYSCALL to ensure when sys_tz is updated they can also
updatee their copy in the vdso.

Signed-off-by: default avatarTony Breeds <tony@bakeyournoodle.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Acked-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6212e3a3

arch/ia64/kernel/time.c

+5 −0
Original line number Diff line number Diff line
@@ -371,6 +371,11 @@ ia64_setup_printk_clock(void) 
		ia64_printk_clock = ia64_itc_printk_clock;

}



/* IA64 doesn't cache the timezone */

void update_vsyscall_tz(void)

{

}



void update_vsyscall(struct timespec *wall, struct clocksource *c)

{

        unsigned long flags;

arch/x86/kernel/vsyscall_64.c

+10 −1
Original line number Diff line number Diff line
@@ -64,6 +64,16 @@ struct vsyscall_gtod_data __vsyscall_gtod_data __section_vsyscall_gtod_data = 
	.sysctl_enabled = 1,

};



void update_vsyscall_tz(void)

{

	unsigned long flags;



	write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);

	/* sys_tz has changed */

	vsyscall_gtod_data.sys_tz = sys_tz;

	write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);

}



void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)

{

	unsigned long flags;
@@ -77,7 +87,6 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) 
	vsyscall_gtod_data.clock.shift = clock->shift;

	vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;

	vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;

	vsyscall_gtod_data.sys_tz = sys_tz;

	vsyscall_gtod_data.wall_to_monotonic = wall_to_monotonic;

	write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);

}

include/linux/clocksource.h

+5 −0
Original line number Diff line number Diff line
@@ -221,10 +221,15 @@ extern void clocksource_resume(void); 


#ifdef CONFIG_GENERIC_TIME_VSYSCALL

extern void update_vsyscall(struct timespec *ts, struct clocksource *c);

extern void update_vsyscall_tz(void);

#else

static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)

{

}



static inline void update_vsyscall_tz(void)

{

}

#endif



#endif /* _LINUX_CLOCKSOURCE_H */

kernel/time.c

+2 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <linux/module.h>

#include <linux/timex.h>

#include <linux/capability.h>

#include <linux/clocksource.h>

#include <linux/errno.h>

#include <linux/syscalls.h>

#include <linux/security.h>
@@ -158,6 +159,7 @@ int do_sys_settimeofday(struct timespec *tv, struct timezone *tz) 
	if (tz) {

		/* SMP safe, global irq locking makes it work. */

		sys_tz = *tz;

		update_vsyscall_tz();

		if (firsttime) {

			firsttime = 0;

			if (!tv)

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