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Message-ID: <20240710203031.188081-4-anthony.l.nguyen@intel.com>
Date: Wed, 10 Jul 2024 13:30:19 -0700
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
kuba@...nel.org,
pabeni@...hat.com,
edumazet@...gle.com,
netdev@...r.kernel.org
Cc: Alexander Lobakin <aleksander.lobakin@...el.com>,
anthony.l.nguyen@...el.com,
nex.sw.ncis.osdt.itp.upstreaming@...el.com,
lihong.yang@...el.com,
willemb@...gle.com,
almasrymina@...gle.com
Subject: [PATCH net-next 03/14] libeth: add cacheline / struct layout assertion helpers
From: Alexander Lobakin <aleksander.lobakin@...el.com>
Add helpers to assert struct field layout, a bit more crazy and
networking-specific than in <linux/cache.h>. They assume you have
3 CL-aligned groups (read-mostly, read-write, cold) in a struct
you want to assert, and nothing besides them.
For 64-bit with 64-byte cachelines, the assertions are as strict
as possible, as the size can then be easily predicted.
For the rest, make sure they don't cross the specified bound.
Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
include/net/libeth/cache.h | 66 ++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)
create mode 100644 include/net/libeth/cache.h
diff --git a/include/net/libeth/cache.h b/include/net/libeth/cache.h
new file mode 100644
index 000000000000..bdb0c043ce61
--- /dev/null
+++ b/include/net/libeth/cache.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2024 Intel Corporation */
+
+#ifndef __LIBETH_CACHE_H
+#define __LIBETH_CACHE_H
+
+#include <linux/cache.h>
+
+/**
+ * libeth_cacheline_group_assert - make sure cacheline group size is expected
+ * @type: type of the structure containing the group
+ * @grp: group name inside the struct
+ * @sz: expected group size
+ */
+#if defined(CONFIG_64BIT) && SMP_CACHE_BYTES == 64
+#define libeth_cacheline_group_assert(type, grp, sz) \
+ static_assert(offsetof(type, __cacheline_group_end__##grp) - \
+ offsetofend(type, __cacheline_group_begin__##grp) == \
+ (sz))
+#define __libeth_cacheline_struct_assert(type, sz) \
+ static_assert(sizeof(type) == (sz))
+#else /* !CONFIG_64BIT || SMP_CACHE_BYTES != 64 */
+#define libeth_cacheline_group_assert(type, grp, sz) \
+ static_assert(offsetof(type, __cacheline_group_end__##grp) - \
+ offsetofend(type, __cacheline_group_begin__##grp) <= \
+ (sz))
+#define __libeth_cacheline_struct_assert(type, sz) \
+ static_assert(sizeof(type) <= (sz))
+#endif /* !CONFIG_64BIT || SMP_CACHE_BYTES != 64 */
+
+#define __libeth_cls1(sz1) SMP_CACHE_ALIGN(sz1)
+#define __libeth_cls2(sz1, sz2) (SMP_CACHE_ALIGN(sz1) + SMP_CACHE_ALIGN(sz2))
+#define __libeth_cls3(sz1, sz2, sz3) \
+ (SMP_CACHE_ALIGN(sz1) + SMP_CACHE_ALIGN(sz2) + SMP_CACHE_ALIGN(sz3))
+#define __libeth_cls(...) \
+ CONCATENATE(__libeth_cls, COUNT_ARGS(__VA_ARGS__))(__VA_ARGS__)
+
+/**
+ * libeth_cacheline_struct_assert - make sure CL-based struct size is expected
+ * @type: type of the struct
+ * @...: from 1 to 3 CL group sizes (read-mostly, read-write, cold)
+ *
+ * When a struct contains several CL groups, it's difficult to predict its size
+ * on different architectures. The macro instead takes sizes of all of the
+ * groups the structure contains and generates the final struct size.
+ */
+#define libeth_cacheline_struct_assert(type, ...) \
+ __libeth_cacheline_struct_assert(type, __libeth_cls(__VA_ARGS__)); \
+ static_assert(__alignof(type) >= SMP_CACHE_BYTES)
+
+/**
+ * libeth_cacheline_set_assert - make sure CL-based struct layout is expected
+ * @type: type of the struct
+ * @ro: expected size of the read-mostly group
+ * @rw: expected size of the read-write group
+ * @c: expected size of the cold group
+ *
+ * Check that each group size is expected and then do final struct size check.
+ */
+#define libeth_cacheline_set_assert(type, ro, rw, c) \
+ libeth_cacheline_group_assert(type, read_mostly, ro); \
+ libeth_cacheline_group_assert(type, read_write, rw); \
+ libeth_cacheline_group_assert(type, cold, c); \
+ libeth_cacheline_struct_assert(type, ro, rw, c)
+
+#endif /* __LIBETH_CACHE_H */
--
2.41.0
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