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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F1F8DCA6015 for ; Fri, 9 Oct 2026 03:27:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4zQBtxSydMxD0aYfwklNmYRMaEN/sazKago4Nve0/4Q=; b=HoYBmVMKTzBqJf lXe0DXzlK1AvpF7i3R42SfvMEUDQHtNCHXbHdghYH92BqIjtgi5jGpLh1W20DWmDD8kJiA20+mZfl yXT9Wa3yv1Jt5irJzbz7UhRge/wOP7swvu9X45npIjgIAiWOVKCBC5pnXUhWnxP85uTckWvI+pSPw As9e954dU3t2aPhKpKc6CnZbVcfeuFBsT1FT0c0WUpuisQBjcJztY17GyZiK1Jy0Dr8Ku+w3FwgYY rOpUtCfH+Oytqt75PtSA2uikzFLZWeeoRvxZw1NxA+70N+8n2LrCtCRdnZ2m3UZWIVCOFrUHjtMUn trkLgM+aUqP4Ye3tDqcg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xF1Gc-00000005Mfa-1QqZ; Fri, 09 Oct 2026 03:27:30 +0000 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xF1GY-00000005MdV-1qoS; Fri, 09 Oct 2026 03:27:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1791516443; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=dyCekRw9sufTyDzZAdbNFK7/Qt5VQKyaiRdhuHgwJrU=; b=U+WbzG6jgZoMteiC/ffr8/lAYnEVYKsB8Ct7Yb4kUZzzf8keytj0VBGBU+GHIK1Sgdjnl5tzS5j2oOJLG3qzJ/rAbaarOfnGkTPgpfItLR9UR0APO8tfqVd6j1qAwMG9NrTPQZdr1ctcyw1USU0LEXzMGHJ9LVDHWFOOXtEPo38= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R581e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037033178;MF=cp0613@linux.alibaba.com;NM=1;PH=DS;RN=23;SR=0;TI=SMTPD_---0XCS-sKT_1791516441; Received: from DESKTOP-S9E58SO.localdomain(mailfrom:cp0613@linux.alibaba.com fp:SMTPD_---0XCS-sKT_1791516441 cluster:ay36) by smtp.aliyun-inc.com; Fri, 09 Oct 2026 11:27:22 +0800 From: Chen Pei To: acme@kernel.org, peterz@infradead.org, mingo@redhat.com, namhyung@kernel.org Cc: mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, james.clark@linaro.org, leo.yan@linux.dev, john.g.garry@oracle.com, will@kernel.org, mike.leach@arm.com, pjw@kernel.org, palmer@dabbelt.com, guoren@kernel.org, anup@brainfault.org, david.laight.linux@gmail.com, linux-perf-users@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] perf riscv: Implement rdtsc() Date: Fri, 9 Oct 2026 11:27:14 +0800 Message-ID: <20261009032715.2841-2-cp0613@linux.alibaba.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261009032715.2841-1-cp0613@linux.alibaba.com> References: <20261009032715.2841-1-cp0613@linux.alibaba.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261008_202726_960240_C9661EE6 X-CRM114-Status: GOOD ( 12.79 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Perf has no riscv implementation of rdtsc(), so it links against the weak stub in util/tsc.c and every caller reads a constant 0 that cannot be told apart from a counter standing still. Implement rdtsc() over the time CSR with rdtime. The time CSR is a TSC equivalent on riscv: readable from user mode, constant frequency, and the same counter riscv's arch_perf_update_userpage() builds the user page conversion fields from, so the counter and perf time share a timebase. Define it for RV64 only. Reading the counter whole on RV32 takes time and timeh in a loop, and no RV32 user in tools/perf needs it that much, so RV32 keeps the weak stub. Reviewed-by: Anup Patel Acked-by: Paul Walmsley # arch/riscv Signed-off-by: Chen Pei --- tools/perf/arch/riscv/util/Build | 1 + tools/perf/arch/riscv/util/tsc.c | 27 +++++++++++++++++++++++++++ 2 files changed, 28 insertions(+) create mode 100644 tools/perf/arch/riscv/util/tsc.c diff --git a/tools/perf/arch/riscv/util/Build b/tools/perf/arch/riscv/util/Build index 2328fb9a30a3..52cd6a481de8 100644 --- a/tools/perf/arch/riscv/util/Build +++ b/tools/perf/arch/riscv/util/Build @@ -1 +1,2 @@ perf-util-y += header.o +perf-util-y += tsc.o diff --git a/tools/perf/arch/riscv/util/tsc.c b/tools/perf/arch/riscv/util/tsc.c new file mode 100644 index 000000000000..3dd419ce9d2a --- /dev/null +++ b/tools/perf/arch/riscv/util/tsc.c @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +#include "../../../util/tsc.h" + +/* + * RV32 is left to the weak stub: reading the counter whole there takes time + * and timeh in a loop, and no RV32 user in tools/perf needs it that much. + */ +#if defined(__riscv) && __riscv_xlen == 64 + +u64 rdtsc(void) +{ + u64 val; + + /* + * The time CSR ticks at a constant frequency and is the same counter + * the kernel feeds into the user page conversion fields through + * sched_clock(), so it is a TSC equivalent here. + */ + asm volatile("rdtime %0" : "=r" (val)); + + return val; +} + +#endif -- 2.50.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv