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Commit 17f6bac2 authored by Chuanhua Lei's avatar Chuanhua Lei Committed by Thomas Gleixner
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x86/tsc: Prevent result truncation on 32bit



Loops per jiffy is calculated by multiplying tsc_khz with 1e3 and then
dividing it by HZ.

Both tsc_khz and the temporary variable holding the multiplication result
are of type unsigned long, so on 32bit the result is truncated to the lower
32bit.

Use u64 as type for the temporary variable and cast tsc_khz to it before
multiplying.

[ tglx: Massaged changelog and removed pointless braces ]

Fixes: cf7a63ef ("x86/tsc: Calibrate tsc only once")
Signed-off-by: default avatarChuanhua Lei <chuanhua.lei@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: yixin.zhu@linux.intel.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@microsoft.com>
Cc: Rajvi Jingar <rajvi.jingar@intel.com>
Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
Link: https://lkml.kernel.org/r/1536228203-18701-1-git-send-email-chuanhua.lei@linux.intel.com
parent 4331f4d5
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