2020-05-07 14:11:53 +00:00
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From 31833711167444fdf5e15ffcc704cf201f96a1b3 Mon Sep 17 00:00:00 2001
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2020-04-23 20:47:21 +00:00
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From: Jiri Benc <jbenc@redhat.com>
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Date: Wed, 19 Feb 2020 11:52:20 +0100
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Subject: [PATCH] redhat: rh_kabi add a comment with warning about
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RH_KABI_EXCLUDE usage
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RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
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RH-Acked-by: Don Zickus <dzickus@redhat.com>
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Upstream status: RHEL only
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We've seen attempts of incorrect RH_KABI_EXCLUDE usage. The macro is
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dangerous and any structure marked by it becomes fragile. It completely
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mutes the kABI checker and a future attempt to whitelist anything using
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a structure annotated by RH_KABI_EXCLUDE will generate easily broken, error
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prone code. Also, it bypasses module loading checks for the structure and
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can lead to kernel crashes triggered by 3rd party modules unless carefully
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prevented by RH_KABI_FORCE_CHANGE.
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As such, it should not be used routinely. The only valid usage is a code
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heavily in flux upstream that is going to be refactored and turned upside
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down, which is indirectly whitelisted and which we expect to need
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backported.
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Any usage of this macro requires deep understanding of how kABI works.
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Add a big fat warning to stop the misuse.
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Upstream Status: RHEL only
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Signed-off-by: Jiri Benc <jbenc@redhat.com>
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---
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include/linux/rh_kabi.h | 11 ++++++++++-
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1 file changed, 10 insertions(+), 1 deletion(-)
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diff --git a/include/linux/rh_kabi.h b/include/linux/rh_kabi.h
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index 4debb7aaad48..b90601e8a657 100644
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--- a/include/linux/rh_kabi.h
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+++ b/include/linux/rh_kabi.h
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@@ -2,7 +2,7 @@
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* rh_kabi.h - Red Hat kABI abstraction header
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*
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* Copyright (c) 2014 Don Zickus
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- * Copyright (c) 2015-2017 Jiri Benc
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+ * Copyright (c) 2015-2018 Jiri Benc
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* Copyright (c) 2015 Sabrina Dubroca, Hannes Frederic Sowa
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* Copyright (c) 2016-2018 Prarit Bhargava
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* Copyright (c) 2017 Paolo Abeni, Larry Woodman
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@@ -93,7 +93,16 @@
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* corrupt memory. Instead, by changing the symbol checksum, such modules
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* won't be loaded by the kernel. This macro should only be used as a
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* last resort when all other KABI workarounds have failed.
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+ *
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* RH_KABI_EXCLUDE
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+ * !!! WARNING: DANGEROUS, DO NOT USE unless you are aware of all the !!!
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+ * !!! implications. This should be used ONLY EXCEPTIONALLY and only !!!
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+ * !!! under specific circumstances. Very likely, this macro does not !!!
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+ * !!! do what you expect it to do. Note that any usage of this macro !!!
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+ * !!! MUST be paired with a RH_KABI_FORCE_CHANGE annotation of !!!
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+ * !!! a suitable symbol (or an equivalent safeguard) and the commit !!!
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+ * !!! log MUST explain why the chosen solution is appropriate. !!!
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+ *
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* Exclude the element from checksum generation. Any such element is
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* considered not to be part of the kABI whitelist and may be changed at
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* will. Note however that it's the responsibility of the developer
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--
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2020-04-27 02:15:20 +00:00
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2.26.2
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2020-04-23 20:47:21 +00:00
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