From nobody Sat Apr 18 02:47:39 2026 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 B4440C433EF for ; Tue, 19 Jul 2022 13:11:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243281AbiGSNLa (ORCPT ); Tue, 19 Jul 2022 09:11:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243223AbiGSNK2 (ORCPT ); Tue, 19 Jul 2022 09:10:28 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 122B351A1E for ; Tue, 19 Jul 2022 05:29:03 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 0F4111F97A; Tue, 19 Jul 2022 12:28:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1658233727; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=RpkV5mcoZ7zrPk8rSX22oR+IY3gNnX4++yEhuGc6rwo=; b=Nf7wuiJSo8jt+B+HDwMMDCqyySI1BsWyIoiSGY/zvIdWm+wBxTUVD5h0r4/g8jVypZOGNW yY5z06qNQI06quegVNWbgaWQrtFR8UvJHxUz07ETsZV7/SeExBDG/NjAZHxC37zUsHJ58W shTblCU0iyJsywWgKLZA+relSNGFzg0= Received: from alley.suse.cz (unknown [10.100.201.202]) by relay2.suse.de (Postfix) with ESMTP id BBD442C141; Tue, 19 Jul 2022 12:28:46 +0000 (UTC) From: Petr Mladek To: John Ogness , Jan Kiszka , Kieran Bingham Cc: Antonio Borneo , linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com Subject: [PATCH v2] scripts/gdb: fix 'lx-dmesg' on 32 bits arch Date: Tue, 19 Jul 2022 14:28:31 +0200 Message-Id: <20220719122831.19890-1-pmladek@suse.com> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Antonio Borneo The type atomic_long_t can have size 4 or 8 bytes, depending on CONFIG_64BIT; it's only content, the field 'counter', is either an int or a s64 value. Current code incorrectly uses the fixed size utils.read_u64() to read the field 'counter' inside atomic_long_t. On 32 bits architectures reading the last element 'tail_id' of the struct prb_desc_ring: struct prb_desc_ring { ... atomic_long_t tail_id; }; causes the utils.read_u64() to access outside the boundary of the struct and the gdb command 'lx-dmesg' exits with error: Python Exception : index out of range Error occurred in Python: index out of range Query the really used atomic_long_t counter type size. Fixes: e60768311af8 ("scripts/gdb: update for lockless printk ringbuffer") Signed-off-by: Antonio Borneo [pmladek@suse.com: Query the really used atomic_long_t counter type size] Tested-by: Antonio Borneo Link: https://lore.kernel.org/r/20220617143758.137307-1-antonio.borneo@foss= .st.com Reviewed-by: John Ogness --- This has somehow fallen through the cracks. Sending as proper patch for rev= iew. Changes against v1: + Query the really used atomic_long_t counter type size scripts/gdb/linux/dmesg.py | 9 +++------ scripts/gdb/linux/utils.py | 14 ++++++++++++-- 2 files changed, 15 insertions(+), 8 deletions(-) diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py index d5983cf3db7d..c771831eb077 100644 --- a/scripts/gdb/linux/dmesg.py +++ b/scripts/gdb/linux/dmesg.py @@ -22,7 +22,6 @@ prb_desc_type =3D utils.CachedType("struct prb_desc") prb_desc_ring_type =3D utils.CachedType("struct prb_desc_ring") prb_data_ring_type =3D utils.CachedType("struct prb_data_ring") printk_ringbuffer_type =3D utils.CachedType("struct printk_ringbuffer") -atomic_long_type =3D utils.CachedType("atomic_long_t") =20 class LxDmesg(gdb.Command): """Print Linux kernel log buffer.""" @@ -68,8 +67,6 @@ class LxDmesg(gdb.Command): off =3D prb_data_ring_type.get_type()['data'].bitpos // 8 text_data_addr =3D utils.read_ulong(text_data_ring, off) =20 - counter_off =3D atomic_long_type.get_type()['counter'].bitpos // 8 - sv_off =3D prb_desc_type.get_type()['state_var'].bitpos // 8 =20 off =3D prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8 @@ -89,9 +86,9 @@ class LxDmesg(gdb.Command): =20 # read in tail and head descriptor ids off =3D prb_desc_ring_type.get_type()['tail_id'].bitpos // 8 - tail_id =3D utils.read_u64(desc_ring, off + counter_off) + tail_id =3D utils.read_atomic_long(desc_ring, off) off =3D prb_desc_ring_type.get_type()['head_id'].bitpos // 8 - head_id =3D utils.read_u64(desc_ring, off + counter_off) + head_id =3D utils.read_atomic_long(desc_ring, off) =20 did =3D tail_id while True: @@ -102,7 +99,7 @@ class LxDmesg(gdb.Command): desc =3D utils.read_memoryview(inf, desc_addr + desc_off, desc= _sz).tobytes() =20 # skip non-committed record - state =3D 3 & (utils.read_u64(desc, sv_off + counter_off) >> d= esc_flags_shift) + state =3D 3 & (utils.read_atomic_long(desc, sv_off) >> desc_fl= ags_shift) if state !=3D desc_committed and state !=3D desc_finalized: if did =3D=3D head_id: break diff --git a/scripts/gdb/linux/utils.py b/scripts/gdb/linux/utils.py index ff7c1799d588..1553f68716cc 100644 --- a/scripts/gdb/linux/utils.py +++ b/scripts/gdb/linux/utils.py @@ -35,13 +35,12 @@ class CachedType: =20 =20 long_type =3D CachedType("long") - +atomic_long_type =3D CachedType("atomic_long_t") =20 def get_long_type(): global long_type return long_type.get_type() =20 - def offset_of(typeobj, field): element =3D gdb.Value(0).cast(typeobj) return int(str(element[field].address).split()[0], 16) @@ -129,6 +128,17 @@ def read_ulong(buffer, offset): else: return read_u32(buffer, offset) =20 +atomic_long_counter_offset =3D atomic_long_type.get_type()['counter'].bitp= os +atomic_long_counter_sizeof =3D atomic_long_type.get_type()['counter'].type= .sizeof + +def read_atomic_long(buffer, offset): + global atomic_long_counter_offset + global atomic_long_counter_sizeof + + if atomic_long_counter_sizeof =3D=3D 8: + return read_u64(buffer, offset + atomic_long_counter_offset) + else: + return read_u32(buffer, offset + atomic_long_counter_offset) =20 target_arch =3D None =20 --=20 2.35.3