tools/slabratetop: Fix error: incomplete definition of type 'struct s…

…lab'

kernel commit 40f3bf0cb04c("mm: Convert struct page to struct slab in functions
used by other subsystems") introduce slab_address() function, commit 6e48a966dfd1
("mm/kasan: Convert to struct folio and struct slab") linux/kasan.h adds a
dependency on the slab struct, This leads to the following problems:

    $ sudo ./slabratetop.py
    In file included from /virtual/main.c:13:
    include/linux/slub_def.h:162:26: warning: call to undeclared function 'slab_address';
    ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
            void *object = x - (x - slab_address(slab)) % cache->size;
                                    ^
    include/linux/slub_def.h:162:46: error: invalid operands to binary expression ('void *' and 'unsigned int')
            void *object = x - (x - slab_address(slab)) % cache->size;
                               ~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~
    include/linux/slub_def.h:164:8: error: incomplete definition of type 'struct slab'
                    (slab->objects - 1) * cache->size;
                     ~~~~^
    include/linux/kasan.h:13:8: note: forward declaration of 'struct slab'
    struct slab;
           ^
    ...

At first, I wanted to fix this with a kernel patch [1], however, bcc as a
downstream project of the kernel, this issue should be solved inside the bcc
project. This is agreed by kernel maintainer and bcc maintainer @yonghong-song.

This solution is provided by @yonghong-song [0].

[0] iovisor#4438
[1] https://lore.kernel.org/all/[email protected]/

Signed-off-by: Rong Tao <[email protected]>
Signed-off-by: Yonghong Song <[email protected]>

tools/slabratetop.py

@@ -14,6 +14,9 @@
 # Licensed under the Apache License, Version 2.0 (the "License")
 #
 # 15-Oct-2016 Brendan Gregg Created this.
+# 23-Jan-2023 Rong Tao Introduce kernel internal data structure and
+# functions to temporarily solve problem for
+# >=5.16(TODO: fix this workaround)
 
 from __future__ import print_function
 from bcc import BPF
@@ -65,6 +68,79 @@
 // 5.9, but it does not hurt to have it here for versions 5.4 to 5.8.
 struct memcg_cache_params {};
 
+// introduce kernel interval slab structure and slab_address() function, solved
+// 'undefined' error for >=5.16. TODO: we should fix this workaround if BCC
+// framework support BTF/CO-RE.
+struct slab {
+ unsigned long __page_flags;
+
+#if defined(CONFIG_SLAB)
+
+ struct kmem_cache *slab_cache;
+ union {
+ struct {
+ struct list_head slab_list;
+ void *freelist; /* array of free object indexes */
+ void *s_mem; /* first object */
+ };
+ struct rcu_head rcu_head;
+ };
+ unsigned int active;
+
+#elif defined(CONFIG_SLUB)
+
+ struct kmem_cache *slab_cache;
+ union {
+ struct {
+ union {
+ struct list_head slab_list;
+#ifdef CONFIG_SLUB_CPU_PARTIAL
+ struct {
+ struct slab *next;
+ int slabs; /* Nr of slabs left */
+ };
+#endif
+ };
+ /* Double-word boundary */
+ void *freelist; /* first free object */
+ union {
+ unsigned long counters;
+ struct {
+ unsigned inuse:16;
+ unsigned objects:15;
+ unsigned frozen:1;
+ };
+ };
+ };
+ struct rcu_head rcu_head;
+ };
+ unsigned int __unused;
+
+#elif defined(CONFIG_SLOB)
+
+ struct list_head slab_list;
+ void *__unused_1;
+ void *freelist; /* first free block */
+ long units;
+ unsigned int __unused_2;
+
+#else
+#error "Unexpected slab allocator configured"
+#endif
+
+ atomic_t __page_refcount;
+#ifdef CONFIG_MEMCG
+ unsigned long memcg_data;
+#endif
+};
+
+// slab_address() will not be used, and NULL will be returned directly, which
+// can avoid adaptation of different kernel versions
+static inline void *slab_address(const struct slab *slab)
+{
+ return NULL;
+}
+
 #ifdef CONFIG_SLUB
 #include <linux/slub_def.h>
 #else