From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45808C4338F for ; Mon, 9 Aug 2021 15:48:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27D0361040 for ; Mon, 9 Aug 2021 15:48:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235818AbhHIPtE (ORCPT ); Mon, 9 Aug 2021 11:49:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:51068 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235757AbhHIPsn (ORCPT ); Mon, 9 Aug 2021 11:48:43 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 33D606101E; Mon, 9 Aug 2021 15:48:23 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mD7B6-003qjI-O5; Mon, 09 Aug 2021 16:27:00 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Mark Rutland , Daniel Lezcano , Thomas Gleixner , Peter Shier , Raghavendra Rao Ananta , Ricardo Koller , Oliver Upton , Will Deacon , Catalin Marinas , Linus Walleij , kernel-team@android.com Subject: [PATCH 13/13] arm64: Add CNT{P,V}CTSS_EL0 alternatives to cnt{p,v}ct_el0 Date: Mon, 9 Aug 2021 16:26:51 +0100 Message-Id: <20210809152651.2297337-14-maz@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210809152651.2297337-1-maz@kernel.org> References: <20210809152651.2297337-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, daniel.lezcano@linaro.org, tglx@linutronix.de, pshier@google.com, rananta@google.com, ricarkol@google.com, oupton@google.com, will@kernel.org, catalin.marinas@arm.com, linus.walleij@linaro.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org CNTPCTSS_EL0 and CNTVCTSS_EL0 are alternatives to the usual CNTPCT_EL0 and CNTVCT_EL0 that do not require a previous ISB to be synchronised (SS stands for Self-Synchronising). Use the ARM64_HAS_ECV capability to control alternative sequences that switch to these low(er)-cost primitives. Note that the counter access in the VDSO is for now left alone until we decide whether we want to allow this. For a good measure, wire the cntvct hooks to also handle CNTVCTSS. Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/arch_timer.h | 30 +++++++++++++++++++++++------ arch/arm64/include/asm/esr.h | 6 ++++++ arch/arm64/include/asm/sysreg.h | 3 +++ arch/arm64/kernel/traps.c | 11 +++++++++++ 4 files changed, 44 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index b2f056db1225..785411a48512 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -64,12 +64,26 @@ DECLARE_PER_CPU(const struct arch_timer_erratum_workaround *, static inline notrace u64 arch_timer_read_cntpct_el0(void) { - return read_sysreg(cntpct_el0); + u64 cnt; + + asm volatile(ALTERNATIVE("isb\n mrs %x0, cntpct_el0", + "nop\n" __mrs_s("%x0", SYS_CNTPCTSS_EL0), + ARM64_HAS_ECV) + : "=r" (cnt)); + + return cnt; } static inline notrace u64 arch_timer_read_cntvct_el0(void) { - return read_sysreg(cntvct_el0); + u64 cnt; + + asm volatile(ALTERNATIVE("isb\n mrs %x0, cntvct_el0", + "nop\n" __mrs_s("%x0", SYS_CNTVCTSS_EL0), + ARM64_HAS_ECV) + : "=r" (cnt)); + + return cnt; } #define arch_timer_reg_read_stable(reg) \ @@ -166,8 +180,10 @@ static __always_inline u64 __arch_counter_get_cntpct(void) { u64 cnt; - isb(); - cnt = read_sysreg(cntpct_el0); + asm volatile(ALTERNATIVE("isb\n mrs %x0, cntpct_el0", + "nop\n" __mrs_s("%x0", SYS_CNTPCTSS_EL0), + ARM64_HAS_ECV) + : "=r" (cnt)); arch_counter_enforce_ordering(cnt); return cnt; } @@ -186,8 +202,10 @@ static __always_inline u64 __arch_counter_get_cntvct(void) { u64 cnt; - isb(); - cnt = read_sysreg(cntvct_el0); + asm volatile(ALTERNATIVE("isb\n mrs %x0, cntvct_el0", + "nop\n" __mrs_s("%x0", SYS_CNTVCTSS_EL0), + ARM64_HAS_ECV) + : "=r" (cnt)); arch_counter_enforce_ordering(cnt); return cnt; } diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index 29f97eb3dad4..a305ce256090 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -227,6 +227,9 @@ #define ESR_ELx_SYS64_ISS_SYS_CNTVCT (ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 2, 14, 0) | \ ESR_ELx_SYS64_ISS_DIR_READ) +#define ESR_ELx_SYS64_ISS_SYS_CNTVCTSS (ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 6, 14, 0) | \ + ESR_ELx_SYS64_ISS_DIR_READ) + #define ESR_ELx_SYS64_ISS_SYS_CNTFRQ (ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 0, 14, 0) | \ ESR_ELx_SYS64_ISS_DIR_READ) @@ -317,6 +320,9 @@ #define ESR_ELx_CP15_64_ISS_SYS_CNTVCT (ESR_ELx_CP15_64_ISS_SYS_VAL(1, 14) | \ ESR_ELx_CP15_64_ISS_DIR_READ) +#define ESR_ELx_CP15_64_ISS_SYS_CNTVCTSS (ESR_ELx_CP15_64_ISS_SYS_VAL(9, 14) | \ + ESR_ELx_CP15_64_ISS_DIR_READ) + #define ESR_ELx_CP15_32_ISS_SYS_CNTFRQ (ESR_ELx_CP15_32_ISS_SYS_VAL(0, 0, 14, 0) |\ ESR_ELx_CP15_32_ISS_DIR_READ) diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 7b9c3acba684..897f9c882895 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -506,6 +506,9 @@ #define SYS_CNTFRQ_EL0 sys_reg(3, 3, 14, 0, 0) +#define SYS_CNTPCTSS_EL0 sys_reg(3, 3, 14, 0, 5) +#define SYS_CNTVCTSS_EL0 sys_reg(3, 3, 14, 0, 6) + #define SYS_CNTP_TVAL_EL0 sys_reg(3, 3, 14, 2, 0) #define SYS_CNTP_CTL_EL0 sys_reg(3, 3, 14, 2, 1) #define SYS_CNTP_CVAL_EL0 sys_reg(3, 3, 14, 2, 2) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index b03e383d944a..16710ca55fbb 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -653,6 +653,12 @@ static const struct sys64_hook sys64_hooks[] = { .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT, .handler = cntvct_read_handler, }, + { + /* Trap read access to CNTVCTSS_EL0 */ + .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, + .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCTSS, + .handler = cntvct_read_handler, + }, { /* Trap read access to CNTFRQ_EL0 */ .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, @@ -729,6 +735,11 @@ static const struct sys64_hook cp15_64_hooks[] = { .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT, .handler = compat_cntvct_read_handler, }, + { + .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK, + .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCTSS, + .handler = compat_cntvct_read_handler, + }, {}, }; -- 2.30.2