From 14055ce53c2d901d826ffad7fb7d6bb8ab46bdfd Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 27 Jun 2018 15:44:02 +0200 Subject: s390x/tcg: avoid overflows in time2tod/tod2time Big values for the TOD/ns clock can result in some overflows that can be avoided. Not all overflows can be handled however, as the conversion either multiplies by 4.096 or divided by 4.096. Apply the trick used in the Linux kernel in arch/s390/include/asm/timex.h for tod_to_ns() and use the same trick also for the conversion in the other direction. Reviewed-by: Thomas Huth Signed-off-by: David Hildenbrand Message-Id: <20180627134410.4901-2-david@redhat.com> Signed-off-by: Cornelia Huck --- target/s390x/internal.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'target') diff --git a/target/s390x/internal.h b/target/s390x/internal.h index e392a02..6cf6334 100644 --- a/target/s390x/internal.h +++ b/target/s390x/internal.h @@ -243,13 +243,14 @@ enum cc_op { /* Converts ns to s390's clock format */ static inline uint64_t time2tod(uint64_t ns) { - return (ns << 9) / 125; + return (ns << 9) / 125 + (((ns & 0xff10000000000000ull) / 125) << 9); + } /* Converts s390's clock format to ns */ static inline uint64_t tod2time(uint64_t t) { - return (t * 125) >> 9; + return ((t >> 9) * 125) + (((t & 0x1ff) * 125) >> 9); } static inline hwaddr decode_basedisp_s(CPUS390XState *env, uint32_t ipb, -- cgit v1.1