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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78D74C433F5 for ; Wed, 15 Dec 2021 15:10:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243736AbhLOPK1 (ORCPT ); Wed, 15 Dec 2021 10:10:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243715AbhLOPK0 (ORCPT ); Wed, 15 Dec 2021 10:10:26 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCD69C061574 for ; Wed, 15 Dec 2021 07:10:25 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1639581023; 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; bh=DlAuCxADJdDedhOdaQ3XkarOK9iIv0+wbxsXvUHhZUQ=; b=SoQP/nH11FTR3gJIz9VCS5MbyNwEIACT6FlivUQRXwVMrx0FchPhjYviW9y5b4JnrCfW7G xP2Z81/lhP83oL4ilnIGpFAOUnhnjaUrhCnJPHF5vsYwsT4RejUXUDl8Muci+Xzm38FmPC df8BEpJm3qC760T02Q16qBiYrPDni7xyB07L5nJaW7N0DsqlGOz8RmUYjJUc39xQoN2ZBY 6ZEeNip+Y10c0NBCk0LTOg5D2jpDYve//VQ7xjza33+bJ6S3wvbUR3GysbsUMsNMIlpwa/ TEt1/j59h3wgivXzJCv9xsApqe6YK0GH2RArkwDVCuE2YrwPT7ysVyRsowXopg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1639581023; 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; bh=DlAuCxADJdDedhOdaQ3XkarOK9iIv0+wbxsXvUHhZUQ=; b=d3GVDNPOL2OhiwyLPhGHPOdIfW3MW9emdEf9DoQxobGM31EIrvKo+ZIcj7l80VP1spxQip fTNqLnn5nDkNNiCQ== To: Petr Mladek Cc: Jan Kiszka , Kieran Bingham , linux-kernel@vger.kernel.org Subject: [PATCH] scripts/gdb: lx-dmesg: read records individually Date: Wed, 15 Dec 2021 16:16:22 +0106 Message-ID: <874k79c3a9.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For the gdb command lx-dmesg, the entire descriptor, info, and text data regions are read into memory before printing any records. For large kernel log buffers, this not only causes a huge delay before seeing any records, but it may also lead to python errors of too much memory allocation. Rather than reading in all these regions in advance, read them as needed and only read the regions for the particular record that is being printed. The gdb macro "dmesg" in Documentation/admin-guide/kdump/gdbmacros.txt already prints out the kernel log buffer like this. Signed-off-by: John Ogness --- scripts/gdb/linux/dmesg.py | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py index a92c55bd8de5..d5983cf3db7d 100644 --- a/scripts/gdb/linux/dmesg.py +++ b/scripts/gdb/linux/dmesg.py @@ -44,19 +44,17 @@ class LxDmesg(gdb.Command): sz = prb_desc_ring_type.get_type().sizeof desc_ring = utils.read_memoryview(inf, addr, sz).tobytes() - # read in descriptor array + # read in descriptor count, size, and address off = prb_desc_ring_type.get_type()['count_bits'].bitpos // 8 desc_ring_count = 1 << utils.read_u32(desc_ring, off) desc_sz = prb_desc_type.get_type().sizeof off = prb_desc_ring_type.get_type()['descs'].bitpos // 8 - addr = utils.read_ulong(desc_ring, off) - descs = utils.read_memoryview(inf, addr, desc_sz * desc_ring_count).tobytes() + desc_addr = utils.read_ulong(desc_ring, off) - # read in info array + # read in info size and address info_sz = printk_info_type.get_type().sizeof off = prb_desc_ring_type.get_type()['infos'].bitpos // 8 - addr = utils.read_ulong(desc_ring, off) - infos = utils.read_memoryview(inf, addr, info_sz * desc_ring_count).tobytes() + info_addr = utils.read_ulong(desc_ring, off) # read in text data ring structure off = printk_ringbuffer_type.get_type()['text_data_ring'].bitpos // 8 @@ -64,12 +62,11 @@ class LxDmesg(gdb.Command): sz = prb_data_ring_type.get_type().sizeof text_data_ring = utils.read_memoryview(inf, addr, sz).tobytes() - # read in text data + # read in text data size and address off = prb_data_ring_type.get_type()['size_bits'].bitpos // 8 text_data_sz = 1 << utils.read_u32(text_data_ring, off) off = prb_data_ring_type.get_type()['data'].bitpos // 8 - addr = utils.read_ulong(text_data_ring, off) - text_data = utils.read_memoryview(inf, addr, text_data_sz).tobytes() + text_data_addr = utils.read_ulong(text_data_ring, off) counter_off = atomic_long_type.get_type()['counter'].bitpos // 8 @@ -102,17 +99,20 @@ class LxDmesg(gdb.Command): desc_off = desc_sz * ind info_off = info_sz * ind + desc = utils.read_memoryview(inf, desc_addr + desc_off, desc_sz).tobytes() + # skip non-committed record - state = 3 & (utils.read_u64(descs, desc_off + sv_off + - counter_off) >> desc_flags_shift) + state = 3 & (utils.read_u64(desc, sv_off + counter_off) >> desc_flags_shift) if state != desc_committed and state != desc_finalized: if did == head_id: break did = (did + 1) & desc_id_mask continue - begin = utils.read_ulong(descs, desc_off + begin_off) % text_data_sz - end = utils.read_ulong(descs, desc_off + next_off) % text_data_sz + begin = utils.read_ulong(desc, begin_off) % text_data_sz + end = utils.read_ulong(desc, next_off) % text_data_sz + + info = utils.read_memoryview(inf, info_addr + info_off, info_sz).tobytes() # handle data-less record if begin & 1 == 1: @@ -125,16 +125,17 @@ class LxDmesg(gdb.Command): # skip over descriptor id text_start = begin + utils.get_long_type().sizeof - text_len = utils.read_u16(infos, info_off + len_off) + text_len = utils.read_u16(info, len_off) # handle truncated message if end - text_start < text_len: text_len = end - text_start - text = text_data[text_start:text_start + text_len].decode( - encoding='utf8', errors='replace') + text_data = utils.read_memoryview(inf, text_data_addr + text_start, + text_len).tobytes() + text = text_data[0:text_len].decode(encoding='utf8', errors='replace') - time_stamp = utils.read_u64(infos, info_off + ts_off) + time_stamp = utils.read_u64(info, ts_off) for line in text.splitlines(): msg = u"[{time:12.6f}] {line}\n".format( base-commit: 0bafb8f3ebc84525d0ae0fcea22d12151b99312f -- 2.30.2