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[47.208.199.57]) by smtp.gmail.com with ESMTPSA id m12-20020a17090a414c00b001bf6d88870csm6563930pjg.55.2022.03.10.07.52.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Mar 2022 07:52:20 -0800 (PST) From: Ben Woodard Mime-Version: 1.0 (1.0) Subject: Re: [Bug default/28954] New: add Linux Kernel symbol namespace support Date: Thu, 10 Mar 2022 07:52:19 -0800 Message-Id: <713ACA03-1A66-4BE8-9EA8-5ECA0C478A46@redhat.com> References: Cc: libabigail@sourceware.org In-Reply-To: To: gprocida at google dot com X-Mailer: iPad Mail (19D52) X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H5, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libabigail@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Mailing list of the Libabigail project List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Mar 2022 15:53:06 -0000 I=E2=80=99m a little confused by this the LKM name spacing doesn=E2=80=99t = seem to use any of the symbol mangling that C++ does. From the links that y= ou posted it seems like the way that the kernel mangles these names is simp= ly by putting =E2=80=9C.=E2=80=9D into the ELF linkage name. Thi= s confuses me because, I would think that this change in linkage name would= show up in ABI reports but your bug description below suggests that it doe= sn=E2=80=99t. I must be missing something. -ben > On Mar 10, 2022, at 5:26 AM, gprocida at google dot com via Libabigail wrote: >=20 > =EF=BB=BFhttps://sourceware.org/bugzilla/show_bug.cgi?id=3D28954 >=20 > Bug ID: 28954 > Summary: add Linux Kernel symbol namespace support > Product: libabigail > Version: unspecified > Status: UNCONFIRMED > Severity: normal > Priority: P2 > Component: default > Assignee: dodji at redhat dot com > Reporter: gprocida at google dot com > CC: libabigail at sourceware dot org > Target Milestone: --- >=20 > Hi. >=20 > We have started to see Linux kernel symbol namespace changes break module > loading, without being picked up by ABI monitoring beforehand. >=20 > If a symbol has a namespace, then any module attempting to use it (run-ti= me > load check) must have imported (compile-time) the namespace. Load failure= can > be commuted to a warning but I doubt we would do that for Android. >=20 > In terms of ABI monitoring, a change to a symbol's namespace should be re= ported > as an ABI diff. >=20 > While it might also be nice to store the imported namespaces per module (= at the > abg-corpus level), without also tracking undefined symbols this wouldn't = allow > any automatic checking of kernel / module compatibility. Also, there is a > compile-time check that does that anyway. We are trying to ensure that > separately built kernel and modules will (continue to) work together. >=20 > At a minimum we need the following: >=20 > * new ELF symbol XML attribute (and possible documentation update) > * new field in ELF symbol > * symtab reader changes to populate this > * XML writer change to print this > * XML reader change to read this > * categorisation of symbol namespace changes (probably the same as for CR= Cs) > * symbol namespace diff generation / reporting >=20 > I'm happy to start work on this, but would welcome any early feedback. >=20 > References >=20 > https://www.kernel.org/doc/html/latest/core-api/symbol-namespaces.html > https://lwn.net/Articles/760045/ > https://lpc.events/event/2/contributions/220/attachments/44/51/01._Symbol= _Namespaces__Plumbers_v2.pdf >=20 > Giuliano. >=20 > --=20 > You are receiving this mail because: > You are on the CC list for the bug. >=20