Commit d2e58ab5 authored by Adrian Hunter's avatar Adrian Hunter Committed by Thomas Gleixner
Browse files

vdso: Add vdso_data:: Max_cycles 



Add vdso_data::max_cycles in preparation to use it to detect potential
multiplication overflow.

Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-7-adrian.hunter@intel.com
parent 1beb35ec

include/vdso/datapage.h

+4 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ struct vdso_timestamp { 
 * @seq:		timebase sequence counter

 * @clock_mode:		clock mode

 * @cycle_last:		timebase at clocksource init

 * @max_cycles:		maximum cycles which won't overflow 64bit multiplication

 * @mask:		clocksource mask

 * @mult:		clocksource multiplier

 * @shift:		clocksource shift
@@ -92,6 +93,9 @@ struct vdso_data { 


	s32			clock_mode;

	u64			cycle_last;

#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT

	u64			max_cycles;

#endif

	u64			mask;

	u32			mult;

	u32			shift;

kernel/time/vsyscall.c

+6 −0
Original line number Diff line number Diff line
@@ -22,10 +22,16 @@ static inline void update_vdso_data(struct vdso_data *vdata, 
	u64 nsec, sec;



	vdata[CS_HRES_COARSE].cycle_last	= tk->tkr_mono.cycle_last;

#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT

	vdata[CS_HRES_COARSE].max_cycles	= tk->tkr_mono.clock->max_cycles;

#endif

	vdata[CS_HRES_COARSE].mask		= tk->tkr_mono.mask;

	vdata[CS_HRES_COARSE].mult		= tk->tkr_mono.mult;

	vdata[CS_HRES_COARSE].shift		= tk->tkr_mono.shift;

	vdata[CS_RAW].cycle_last		= tk->tkr_raw.cycle_last;

#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT

	vdata[CS_RAW].max_cycles		= tk->tkr_raw.clock->max_cycles;

#endif

	vdata[CS_RAW].mask			= tk->tkr_raw.mask;

	vdata[CS_RAW].mult			= tk->tkr_raw.mult;

	vdata[CS_RAW].shift			= tk->tkr_raw.shift;