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vdso: Add vdso_data:: Max_cycles

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

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-7-adrian.hunter@intel.com
This commit is contained in:
Adrian Hunter 2024-03-25 08:40:10 +02:00 committed by Thomas Gleixner
parent 1beb35ec61
commit d2e58ab5cd
2 changed files with 10 additions and 0 deletions
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4
include/vdso/datapage.h
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@ -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;

6
kernel/time/vsyscall.c
View File

@ -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;