9b53592daf
* Mon Jun 29 2020 Fedora Kernel Team <kernel-team@fedoraproject.org> [5.8.0-0.rc3.1] - v5.8-rc3 rebase - s390x-zfcpdump: Handle missing Module.symvers file (Don Zickus) - Updated changelog for the release based on 8be3a53e18e0 (Fedora Kernel Team) Resolves: rhbz# Signed-off-by: Augusto Caringi <acaringi@redhat.com>
102 lines
4.0 KiB
Diff
102 lines
4.0 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Jiri Benc <jbenc@redhat.com>
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Date: Wed, 19 Feb 2020 11:52:19 +0100
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Subject: [PATCH] redhat: rh_kabi: introduce RH_KABI_EXTEND_WITH_SIZE
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
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RH-Acked-by: Hangbin Liu <haliu@redhat.com>
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Upstream status: RHEL only
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This allows addition of a struct into struct while reserving extra space.
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See the documentation in rh_kabi.h for details.
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The check for size is automatically disabled in -debug kernels that have
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many fields larger than the production kernels (mutexes etc.) and that are
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not under kABI guarantee.
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I'm also moving a misplaced comment for RH_KABI_FILL_HOLE.
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(Pointed out by Sabrina:) We need to force align the added field to 8 byte
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offset. Otherwise, if the required alignment of the added field changed
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later (e.g. it was a structure with only a single field that was changed
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from int to char) and the previous field was smaller than long, it could
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lead to the whole union shifting position and offsets of the following
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fields could change. It's also safer to align the size, too.
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Let the 'size' parameter specify number of longs to be added and not number
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of bytes. Note we assume a 64 bit architecture, which is the case for RHEL.
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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 | 29 ++++++++++++++++++++++++++++-
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1 file changed, 28 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 cdc636d3013d..4debb7aaad48 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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@@ -45,11 +45,24 @@
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* RH_KABI_EXTEND
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* Simple macro for adding a new element to a struct.
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*
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- * Warning: only use if a hole exists for _all_ arches. Use pahole to verify.
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+ * RH_KABI_EXTEND_WITH_SIZE
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+ * Adds a new element (usually a struct) to a struct and reserves extra
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+ * space for the new element. The provided 'size' is the total space to
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+ * be added in longs (i.e. it's 8 * 'size' bytes), including the size of
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+ * the added element. It is automatically checked that the new element
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+ * does not overflow the reserved space, now nor in the future. However,
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+ * no attempt is done to check the content of the added element (struct)
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+ * for kABI conformance - kABI checking inside the added element is
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+ * effectively switched off.
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+ * For any struct being added by RH_KABI_EXTEND_WITH_SIZE, it is
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+ * recommended its content to be documented as not covered by kABI
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+ * guarantee.
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*
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* RH_KABI_FILL_HOLE
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* Simple macro for filling a hole in a struct.
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*
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+ * Warning: only use if a hole exists for _all_ arches. Use pahole to verify.
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+ *
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* RH_KABI_RENAME
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* Simple macro for renaming an element without changing its type. This
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* macro can be used in bitfields, for example.
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@@ -133,8 +146,12 @@
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_Static_assert(__alignof__(struct{_new;}) <= __alignof__(struct{_orig;}), \
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__FILE__ ":" __stringify(__LINE__) ": " __stringify(_orig) " is not aligned the same as " __stringify(_new) RH_KABI_ALIGN_WARNING); \
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}
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+# define __RH_KABI_CHECK_SIZE(_item, _size) \
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+ _Static_assert(sizeof(struct{_item;}) <= _size, \
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+ __FILE__ ":" __stringify(__LINE__) ": " __stringify(_item) " is larger than the reserved size (" __stringify(_size) " bytes)" RH_KABI_ALIGN_WARNING)
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#else
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# define __RH_KABI_CHECK_SIZE_ALIGN(_orig, _new)
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+# define __RH_KABI_CHECK_SIZE(_item, _size)
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#endif
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# define _RH_KABI_DEPRECATE(_type, _orig) _type rh_reserved_##_orig
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@@ -186,6 +203,16 @@
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#define RH_KABI_EXCLUDE(_elem) _RH_KABI_EXCLUDE(_elem);
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+/*
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+ * Extending a struct while reserving extra space.
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+ */
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+#define RH_KABI_EXTEND_WITH_SIZE(_new, _size) \
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+ RH_KABI_EXTEND(union { \
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+ _new; \
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+ unsigned long __UNIQUE_ID(rh_kabi_reserved)[_size]; \
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+ __RH_KABI_CHECK_SIZE(_new, 8 * (_size)); \
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+ })
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+
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/*
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* RHEL macros to extend structs.
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*
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--
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2.25.4
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