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clockcalib: Fix an overflow bug

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tc_counter_mask is an unsigned int and in the TSC timecounter is equal
to UINT_MAX, so the addition tc->tc_counter_mask + 1 can overflow to 0,
resulting in a hang during boot.

Fixes:		c2705ceaeb09 ("x86: Speed up clock calibration")
Reviewed by:	cperciva
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D33956
This commit is contained in:
Mark Johnston 2022-01-20 08:23:38 -05:00
parent e0282802a6
commit c3196306f0
1 changed files with 1 additions and 1 deletions
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2
sys/kern/subr_clockcalib.c
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@ -108,7 +108,7 @@ clockcalib(uint64_t (*clk)(void), const char *clkname)
clk1 = clk() - clk0;
t1 = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
while (t1 + tadj < tlast)
tadj += tc->tc_counter_mask + 1;
tadj += (uint64_t)tc->tc_counter_mask + 1;
tlast = t1 + tadj;
t1 += tadj - t0;