From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49240) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zleih-0001oi-Vc for qemu-devel@nongnu.org; Mon, 12 Oct 2015 11:09:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zleid-0001uk-Ry for qemu-devel@nongnu.org; Mon, 12 Oct 2015 11:08:59 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:34870) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zleid-0001uH-N8 for qemu-devel@nongnu.org; Mon, 12 Oct 2015 11:08:55 -0400 From: Christopher Covington Date: Mon, 12 Oct 2015 11:07:49 -0400 Message-Id: <1444662470-13045-3-git-send-email-cov@codeaurora.org> In-Reply-To: <1444662470-13045-1-git-send-email-cov@codeaurora.org> References: <5612EDA5.9010506@redhat.com> <1444662470-13045-1-git-send-email-cov@codeaurora.org> Subject: [Qemu-devel] [kvm-unit-tests PATCHv4 2/3] arm: pmu: Check cycle count increases List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: drjones@redhat.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, wei@redhat.com Cc: alindsay@codeaurora.org, croberts@codeaurora.org, Christopher Covington , shannon.zhao@linaro.org, alistair.francis@xilinx.com Ensure that reads of the PMCCNTR_EL0 are monotonically increasing, even for the smallest delta of two subsequent reads. Signed-off-by: Christopher Covington --- arm/pmu.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/arm/pmu.c b/arm/pmu.c index 42d0ee1..ae81970 100644 --- a/arm/pmu.c +++ b/arm/pmu.c @@ -14,6 +14,8 @@ */ #include "libcflat.h" +#define NR_SAMPLES 10 + #if defined(__arm__) static inline uint32_t get_pmcr(void) { @@ -22,6 +24,19 @@ static inline uint32_t get_pmcr(void) asm volatile("mrc p15, 0, %0, c9, c12, 0" : "=r" (ret)); return ret; } + +static inline void set_pmcr(uint32_t pmcr) +{ + asm volatile("mcr p15, 0, %0, c9, c12, 0" : : "r" (pmcr)); +} + +static inline unsigned long get_pmccntr(void) +{ + unsigned long cycles; + + asm volatile("mrc p15, 0, %0, c9, c13, 0" : "=r" (cycles)); + return cycles; +} #elif defined(__aarch64__) static inline uint32_t get_pmcr(void) { @@ -30,6 +45,19 @@ static inline uint32_t get_pmcr(void) asm volatile("mrs %0, pmcr_el0" : "=r" (ret)); return ret; } + +static inline void set_pmcr(uint32_t pmcr) +{ + asm volatile("msr pmcr_el0, %0" : : "r" (pmcr)); +} + +static inline unsigned long get_pmccntr(void) +{ + unsigned long cycles; + + asm volatile("mrs %0, pmccntr_el0" : "=r" (cycles)); + return cycles; +} #endif struct pmu_data { @@ -72,11 +100,37 @@ static bool check_pmcr(void) return pmu.implementer != 0; } +/* + * Ensure that the cycle counter progresses between back-to-back reads. + */ +static bool check_cycles_increase(void) +{ + struct pmu_data pmu; + + pmu.enable = 1; + set_pmcr(pmu.pmcr_el0); + + for (int i = 0; i < NR_SAMPLES; i++) { + unsigned long a, b; + + a = get_pmccntr(); + b = get_pmccntr(); + + if (a >= b) { + printf("Read %ld then %ld.\n", a, b); + return false; + } + } + + return true; +} + int main(void) { report_prefix_push("pmu"); report("Control register", check_pmcr()); + report("Monotonically increasing cycle count", check_cycles_increase()); return report_summary(); } -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project