Import and compile code for article 6.5

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+/* Copyright (C) 2000 Thomas Petazzoni
+   Copyright (C) 2004 David Decotigny
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+#ifndef _SOS_KMEM_SLAB_H_
+#define _SOS_KMEM_SLAB_H_
+
+/**
+ * @file kmem_slab.h
+ *
+ * Kernel Memory Allocator based on Bonwick's slab llocator (Solaris
+ * 2.4, Linux 2.4). This allocator achieves good memory utilization
+ * ratio (memory effectively used / memory requested) ie limited
+ * fragmentation, while elegantly handling cache-effect considerations
+ * (TLB locality through the notion of "cache" of slabs, and the
+ * dcache utilization through the notion of cache colouring to
+ * decrease the conflicts in the dcache for accesses to different data
+ * in the same cache).
+ *
+ * This allocator relies on the range allocator (kmem_vmm.h) to
+ * allocate the slabs, which itself relies on the slab allocator to
+ * allocate its "range" data structures, thus leading to a
+ * chicken-and-egg problem. We solve this problem by introducing the
+ * notion of "min_free_objs" for the slab caches, in order for the cache
+ * of ranges to always have enough ranges in reserve to complete the
+ * range allocation before being urged to allocate a new slab of
+ * ranges, which would require the allocation of a new range.
+ *
+ * Compared to Bonwick's recommendations, we don't handle ctor/dtor
+ * routines on the objects, so that we can alter the objects once they
+ * are set free. Thus, the list of free object is stored in the free
+ * objects themselves, not alongside the objects (this also implies that
+ * the SOS_KSLAB_CREATE_MAP flag below is meaningless). We also don't
+ * implement the cache colouring (trivial to add, but we omit it for
+ * readability reasons), and the only alignment constraint we respect
+ * is that allocated objects are aligned on a 4B boundary: for other
+ * alignment constraints, the user must integrate them in the
+ * "object_size" parameter to "sos_kmem_cache_create()".
+ *
+ * References :
+ * - J. Bonwick's paper, "The slab allocator: An object-caching kernel
+ *   memory allocator", In USENIX Summer 1994 Technical Conference
+ * - The bible, aka "Unix internals : the new frontiers" (section
+ *   12.10), Uresh Vahalia, Prentice Hall 1996, ISBN 0131019082
+ * - "The Linux slab allocator", B. Fitzgibbons,
+ *   http://www.cc.gatech.edu/people/home/bradf/cs7001/proj2/
+ * - The Kos, http://kos.enix.org/
+ */
+#include <sos/types.h>
+#include <sos/errno.h>
+
+/** Opaque data structure that defines a Cache of slabs */
+struct sos_kslab_cache;
+
+/** Opaque data structure that defines a slab. Exported only to
+    kmem_vmm.h */
+struct sos_kslab;
+
+#include "kmem_vmm.h"
+
+
+/** The maximum  allowed pages for each slab */
+#define MAX_PAGES_PER_SLAB 32 /* 128 kB */
+
+
+/**
+ * Initialize the slab cache of slab caches, and prepare the cache of
+ * kmem_range for kmem_vmm.
+ *
+ * @param kernel_core_base The virtual address of the first byte used
+ * by the kernel code/data
+ *
+ * @param kernel_core_top The virtual address of the first byte after
+ * the kernel code/data.
+ *
+ * @param sizeof_struct_range the size of the objects (aka "struct
+ * sos_kmem_vmm_ranges") to be allocated in the cache of ranges
+ *
+ * @param first_struct_slab_of_caches (output value) the virtual
+ * address of the first slab structure that gets allocated for the
+ * cache of caches. The function actually manually allocate the first
+ * slab of the cache of caches because of a chicken-and-egg thing. The
+ * address of the slab is used by the kmem_vmm_setup routine to
+ * finalize the allocation of the slab, in order for it to behave like
+ * a real slab afterwards.
+ *
+ * @param first_slab_of_caches_base (output value) the virtual address
+ * of the slab associated to the slab structure.
+ *
+ * @param first_slab_of_caches_nb_pages (output value) the number of
+ * (virtual) pages used by the first slab of the cache of caches.
+ *
+ * @param first_struct_slab_of_ranges (output value) the virtual address
+ * of the first slab that gets allocated for the cache of ranges. Same
+ * explanation as above.
+ *
+ * @param first_slab_of_ranges_base (output value) the virtual address
+ * of the slab associated to the slab structure.
+ *
+ * @param first_slab_of_ranges_nb_pages (output value) the number of
+ * (virtual) pages used by the first slab of the cache of ranges.
+ *
+ * @return the cache of kmem_range immediatly usable
+ */
+struct sos_kslab_cache *
+sos_kmem_cache_subsystem_setup_prepare(sos_vaddr_t kernel_core_base,
+				       sos_vaddr_t kernel_core_top,
+				       sos_size_t  sizeof_struct_range,
+				       /* results */
+				       struct sos_kslab **first_struct_slab_of_caches,
+				       sos_vaddr_t *first_slab_of_caches_base,
+				       sos_count_t *first_slab_of_caches_nb_pages,
+				       struct sos_kslab **first_struct_slab_of_ranges,
+				       sos_vaddr_t *first_slab_of_ranges_base,
+				       sos_count_t *first_slab_of_ranges_nb_pages);
+
+/**
+ * Update the configuration of the cache subsystem once the vmm
+ * subsystem has been fully initialized
+ */
+sos_ret_t
+sos_kmem_cache_subsystem_setup_commit(struct sos_kslab *first_struct_slab_of_caches,
+				      struct sos_kmem_range *first_range_of_caches,
+				      struct sos_kslab *first_struct_slab_of_ranges,
+				      struct sos_kmem_range *first_range_of_ranges);
+
+
+/*
+ * Flags for sos_kmem_cache_create()
+ */
+/** The slabs should be initially mapped in physical memory */
+#define SOS_KSLAB_CREATE_MAP  (1<<0)
+/** The object should always be set to zero at allocation (implies
+    SOS_KSLAB_CREATE_MAP) */
+#define SOS_KSLAB_CREATE_ZERO (1<<1)
+
+/**
+ * @note this function MAY block (involved allocations are not atomic)
+ * @param name must remain valid during the whole cache's life
+ *             (shallow copy) !
+ * @param cache_flags An or-ed combination of the SOS_KSLAB_CREATE_* flags
+ */
+struct sos_kslab_cache *
+sos_kmem_cache_create(const char* name,
+		      sos_size_t  object_size,
+		      sos_count_t pages_per_slab,
+		      sos_count_t min_free_objects,
+		      sos_ui32_t  cache_flags);
+
+sos_ret_t sos_kmem_cache_destroy(struct sos_kslab_cache *kslab_cache);
+
+
+/*
+ * Flags for sos_kmem_cache_alloc()
+ */
+/** Allocation should either succeed or fail, without blocking */
+#define SOS_KSLAB_ALLOC_ATOMIC (1<<0)
+
+/**
+ * Allocate an object from the given cache.
+ *
+ * @param alloc_flags An or-ed combination of the SOS_KSLAB_ALLOC_* flags
+ */
+sos_vaddr_t sos_kmem_cache_alloc(struct sos_kslab_cache *kslab_cache,
+				 sos_ui32_t alloc_flags);
+
+
+/**
+ * Free an object (assumed to be already allocated and not already
+ * free) at the given virtual address.
+ */
+sos_ret_t sos_kmem_cache_free(sos_vaddr_t vaddr);
+
+
+/*
+ * Function reserved to kmem_vmm.c. Does almost everything
+ * sos_kmem_cache_free() does, except it does not call
+ * sos_kmem_vmm_del_range() if it needs to. This is aimed at avoiding
+ * large recursion when a range is freed with
+ * sos_kmem_vmm_del_range().
+ *
+ * @param the_range The range structure to free
+ *
+ * @return NULL when the range containing 'the_range' still contains
+ * other ranges, or the address of the range which owned 'the_range'
+ * if it becomes empty.
+ */
+struct sos_kmem_range *
+sos_kmem_cache_release_struct_range(struct sos_kmem_range *the_range);
+
+
+#endif /* _SOS_KMEM_SLAB_H_ */