From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-relay-canonical-1.canonical.com (smtp-relay-canonical-1.canonical.com [185.125.188.121]) (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 B7A4A2F5328; Sun, 7 Jun 2026 07:30:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.188.121 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780817409; cv=none; b=YDqd79DNER5M07f2mK2nXZjIFEcQvX82Yla+c7uAU83rcpDUeVfOeb+44ygl39G1jVBWYFJ9kbwXtITrINV5UHca1vVgJjlXfhKJEQCOD6WH2khBMzw4JQuFfaVsKE0oBtFiqccn5kdNFIZB6ftcbBLLlvCUR3droEXJl7fWoNg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780817409; c=relaxed/simple; bh=RkQF8lRbTFbKoWVeRbYJJtgDjACBKW9f4O6+Zj+KJwQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=YRx0rAFsf9FvfXE5wibVWnSdGSciD/G+YnwFwbch9dRaTR10mEa1tdSRIZqmrPNJJEGh0ioL91MCwTNxZ5bXv/UtRtjUndpTkzHcZMXq19E2xtVvIBA8aH7Ohv8Y8rWMJYz8sZFkn3Fq/ozGf4x42eLUbFcBO+rQfST5jnfp22s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=canonical.com; spf=pass smtp.mailfrom=canonical.com; dkim=pass (4096-bit key) header.d=canonical.com header.i=@canonical.com header.b=it4IPQRc; arc=none smtp.client-ip=185.125.188.121 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=canonical.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=canonical.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=canonical.com header.i=@canonical.com header.b="it4IPQRc" Received: from hwang4-g16.. (unknown [120.244.199.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPSA id B19673F861; Sun, 7 Jun 2026 07:24:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20251003; t=1780817078; bh=ddikXD3l8TYjtFnVsxE8N0l73vEnH4C/n+VO9I+q5cc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=it4IPQRcsCT6KdGN18nITlblRVKq6EImDBlDcwQfsVzruEcHYiZZbIUVDfEt+Zvmk weaS4ACzupm8r7FQ4Vz3kBbykmjsAcpXE2WhXmswJ2ncxisekb+hLYdHWZdQdNR4Qf vN3T9GZh2cSkKAvyD5qbp5F+ow5bko3JMUtCO+b6y1db/lUAPXlFTU1xKjeEKcU9gG 8Hog3tPexSt/hMZFTcwwhFCv8IQod+nKjaTaGtMPuq2kuEL1i34XtBTXUcGO+mz0// v8rDGad+zSYE4gd5/aTuefMN0mlZL2CGiwsfQNvOU25o0drAUhdR2f1fnjiRyfogRf J90Aau6gFU5Tcwe7W5fo8GOPjFTv0qWg7/200YDLh9QAbsCDkX5PBmYixJ9i/94rIr 8u1DFBcTCae2Oy+QRAJGS4nBF1I5jO6R3Z/r5Rwv5YaNfDSl4SzZCwl9AigVoyF4Ji yBQKKoiHeatjp/X8g+o2aHIPfy6JDr6kAuXnr6T4h0O9Q0IpPsCt1hvd0CAl7GwRhL Re8xSkb5++ycp7BOR6CuYy4FAUUVfm6JrLNiNv0QFFDBmReaWaCd4n8OGMl0yYsUlp 0SIDTSE7M5FpSnYNM99qI4kvIi2lojlqjcVS/5fh/ZeLSXNir9i0rEM1B10W3kb092 dmqJhvlHXb2Go2k7qhza7VoM= From: Hui Wang To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, pjw@kernel.org, linux-trace-kernel@vger.kernel.org, shuah@kernel.org, wangfushuai@baidu.com, linux-kselftest@vger.kernel.org Cc: hui.wang@canonical.com Subject: [PATCH 0/2] ring-buffer: Fix forced 8-byte alignment event length Date: Sun, 7 Jun 2026 15:24:29 +0800 Message-ID: <20260607072431.125633-1-hui.wang@canonical.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series fixes the event length reported by ring_buffer_event_length() when RB_FORCE_8BYTE_ALIGNMENT is enabled, and updates the ftrace trace_marker_raw selftest to account for that layout. On architectures where CONFIG_HAVE_64BIT_ALIGNED_ACCESS is enabled, the ring buffer forces 8-byte alignment. In that mode, the event length is stored in event->array[0] even for small data events, and the payload starts from event->array[1]. However, ring_buffer_event_length() only subtracted the extra length field for large events. As a result, small events reported a payload length 4 bytes larger than expected. This was observed on riscv64 with CONFIG_HAVE_64BIT_ALIGNED_ACCESS=y when running the ftrace trace_marker_raw.tc selftest. The first patch fixes the ring-buffer length calculation. The second patch updates the selftest expectation when the running kernel uses forced 8-byte alignment. Hui Wang (2): ring-buffer: Fix event length with forced 8-byte alignment selftests/ftrace: Account for 8-byte aligned trace_marker_raw events kernel/trace/ring_buffer.c | 3 +- .../ftrace/test.d/00basic/trace_marker_raw.tc | 16 +++++++-- .../testing/selftests/ftrace/test.d/functions | 33 +++++++++++++++++++ 3 files changed, 48 insertions(+), 4 deletions(-) -- 2.43.0