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From: Wilco Dijkstra <wilco@sourceware.org>
To: glibc-cvs@sourceware.org
Subject: [glibc] AArch64: Fix HP_TIMING_DIFF computation [BZ# 29329]
Date: Wed, 22 Feb 2023 17:17:35 +0000 (GMT)	[thread overview]
Message-ID: <20230222171735.DBF013858D33@sourceware.org> (raw)

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=311a7e0256975275d97077f1af338bc9caf0c837

commit 311a7e0256975275d97077f1af338bc9caf0c837
Author: Jun Tang <juntangc@amazon.com>
Date:   Wed Feb 22 16:45:59 2023 +0000

    AArch64: Fix HP_TIMING_DIFF computation [BZ# 29329]
    
    Fix the computation to allow for cntfrq_el0 being larger than 1GHz.
    Assume cntfrq_el0 is a multiple of 1MHz to increase the maximum
    interval (1024 seconds at 1GHz).
    
    Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

Diff:
---
 sysdeps/aarch64/hp-timing.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/aarch64/hp-timing.h b/sysdeps/aarch64/hp-timing.h
index c8469e3011..b97e878f7b 100644
--- a/sysdeps/aarch64/hp-timing.h
+++ b/sysdeps/aarch64/hp-timing.h
@@ -41,7 +41,7 @@ typedef uint64_t hp_timing_t;
 #define HP_TIMING_DIFF(Diff, Start, End)			\
 ({  hp_timing_t freq;						\
     __asm__ __volatile__ ("mrs %0, cntfrq_el0" : "=r" (freq));	\
-   (Diff) = ((End) - (Start)) * (UINT64_C(1000000000) / freq);	\
+   (Diff) = (((End) - (Start)) * UINT64_C(1000000000 >> 6)) / (freq >> 6); \
 })
 
 #endif	/* hp-timing.h */

                 reply	other threads:[~2023-02-22 17:17 UTC|newest]

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