From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 16A2B2F7AD0 for ; Mon, 24 Nov 2025 09:27:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763976444; cv=none; b=Q11f9HoVbOfgVtBaTMnv0TqZdA21z4rHEuuGjuP4loQoLFx0wS4pKo/xhQA74avHjGM+j5atrrATe0J404XDJh/idGRUp3tlsKSsM7bUq0OhsF63qq2H2MkVvXAQc/x4+g4+CO4cukShUvrEBkszmu9c/xOYum0FeMyGDixtUF8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763976444; c=relaxed/simple; bh=DA50pH/bH7RkpXFI/IVMIlEZTs3ulo+9xZt4InyaF8g=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=r6a6xAKpSaflbyDIbw+24VXp7GBdGrwM6fJqhj45vho+qRK9EFSjVOkyQhh6a7PU/ymKIcsUgW4jf4YMsqv9j1qDzZaQyB7G8ktsaVblDWEK3REQB5rlsG1K3x3xSuf8WOe/kC3ngNQpFvzULgM1fnDJr5Pvkk3aEwb599iJebs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ZQfTV7FJ; arc=none smtp.client-ip=91.218.175.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ZQfTV7FJ" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763976428; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=c2MmwLtyNn3QPKov4Wt478LY9eJ7kFXDOMhNB2ZB3vE=; b=ZQfTV7FJ0iCAOcpiaP+ajlMKrMphtDsVC7ggc2WWI/lMhOEmtPjG6lb6ddXtnAZgnpWA4q 0V/d4bAkNa19TtcPR7zwgun1PVGDCmOvdAvH5r/MEc04KfsUWkALSOGaqraqyKVnL/I60P FLuhkdOHUp89NKSxD6Zj2xUPilICsyc= From: George Guo Subject: [PATCH v2 0/2] LoongArch: Add 128-bit atomic cmpxchg support (v2) Date: Mon, 24 Nov 2025 17:26:28 +0800 Message-Id: <20251124-2-v2-0-b38216e25fd9@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAMQkJGkC/02MQQrCMBBFr1JmbWQyNlVceQ/pwmamdkBSSTRUS u5u7Mrl+/z3VkgSVRKcmxWiZE06hwq0a8BPt3AXo1wZCMlZS2jIMB5OHQ3kx46h/p5RRl22xrW vPGl6zfGzJbP9rf92tgbNEd3Avm3RObw8NLyXPUuGvpTyBcp6t1CSAAAA X-Change-ID: 20251120-2-d03862b2cf6d To: Huacai Chen , WANG Xuerui Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, George Guo , George Guo X-Developer-Signature: v=1; a=ed25519-sha256; t=1763976426; l=2242; i=dongtai.guo@linux.dev; s=20251103; h=from:subject:message-id; bh=DA50pH/bH7RkpXFI/IVMIlEZTs3ulo+9xZt4InyaF8g=; b=zQkTj1f5lawY/7uZKqJbSGUb3tTBFvJsNIbHy9B3asj1ZR0OVurqzq5AYz+WLiiPYvzFHbDaD eRv2hTgHdu6CrHq1GYeKIBSJti+1OZXHEZC8W5n3VpLPainOl2WNtWC X-Developer-Key: i=dongtai.guo@linux.dev; a=ed25519; pk=yHUJPGx/kAXutP/NSHpj7hWW0KQNlv3w9H6ju4qUoTM= X-Migadu-Flow: FLOW_OUT This patch series adds 128-bit atomic compare-and-exchange support for LoongArch architecture, which fixes BPF scheduler test failures caused by missing 128-bit atomics support. The series consists of two patches: 1. "LoongArch: Add 128-bit atomic cmpxchg support" - Implements 128-bit atomic compare-and-exchange using LoongArch's LL.D/SC.Q instructions - Fixes BPF scheduler test failures (scx_central scx_qmap) where kmalloc_nolock_noprof returns NULL due to missing 128-bit atomics, leading to -ENOMEM errors during scheduler initialization 2. "LoongArch: Enable 128-bit atomics cmpxchg support" - Adds select HAVE_CMPXCHG_DOUBLE and select HAVE_ALIGNED_STRUCT_PAGE in Kconfig to enable 128-bit atomic cmpxchg support The issue was identified through BPF scheduler test failures where scx_central and scx_qmap schedulers would fail to initialize. Testing was performed using the scx_qmap scheduler from tools/sched_ext/, confirming that the patches resolve the initialization failures. Signed-off-by: George Guo --- Changes in v2: - Use a normal ld.d for the high word instead of ll.d to avoid race condition - Insert a dbar between ll.d and ld.d to prevent reordering - Simply __cmpxchg128_asm("ll.d", "sc.q", ptr, o, n) to __cmpxchg128_asm(ptr, o, n) - Fix address operand constraints after testing different approaches: * ld.d with "m" * ll.d with "ZC", * sc.q with "ZB"(alternative constraints caused issues: - "r" caused system hang - "ZC" caused compiler error: {standard input}: Assembler messages: {standard input}:10037: Fatal error: Immediate overflow. format: u0:0 ) - Link to v1: https://lore.kernel.org/r/20251120-2-v1-0-705bdc440550@linux.dev --- George Guo (2): LoongArch: Add 128-bit atomic cmpxchg support LoongArch: Enable 128-bit atomics cmpxchg support arch/loongarch/Kconfig | 2 ++ arch/loongarch/include/asm/cmpxchg.h | 47 ++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) --- base-commit: d5ae5ac32615e4af729f0610fdc11ff4f4798aef change-id: 20251120-2-d03862b2cf6d Best regards, -- George Guo