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[81.2.115.148]) by smtp.gmail.com with ESMTPSA id o6sm26573508wra.27.2019.07.01.09.40.03 for (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 01 Jul 2019 09:40:04 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Date: Mon, 1 Jul 2019 17:39:15 +0100 Message-Id: <20190701163943.22313-19-peter.maydell@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190701163943.22313-1-peter.maydell@linaro.org> References: <20190701163943.22313-1-peter.maydell@linaro.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.221.66 Subject: [Qemu-devel] [PULL 18/46] aspeed/timer: Ensure positive muldiv delta X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Christian Svensson If the host decrements the counter register that results in a negative delta. This is then passed to muldiv64 which only handles unsigned numbers resulting in bogus results. This fix ensures the delta being operated on is positive. Test case: kexec a kernel using aspeed_timer and it will freeze on the second bootup when the kernel initializes the timer. With this patch that no longer happens and the timer appears to run OK. Signed-off-by: Christian Svensson Signed-off-by: Cédric Le Goater Reviewed-by: Joel Stanley Reviewed-by: Andrew Jeffery Message-id: 20190618165311.27066-12-clg@kaod.org Signed-off-by: Peter Maydell --- hw/timer/aspeed_timer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c index 745eb8608b5..29cc5e80708 100644 --- a/hw/timer/aspeed_timer.c +++ b/hw/timer/aspeed_timer.c @@ -275,7 +275,11 @@ static void aspeed_timer_set_value(AspeedTimerCtrlState *s, int timer, int reg, int64_t delta = (int64_t) value - (int64_t) calculate_ticks(t, now); uint32_t rate = calculate_rate(t); - t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate); + if (delta >= 0) { + t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate); + } else { + t->start -= muldiv64(-delta, NANOSECONDS_PER_SECOND, rate); + } aspeed_timer_mod(t); } break;