include/nucleus/heap.h

/*
 * @note Copyright (C) 2001,2002,2003 Philippe Gerum <rpm@xenomai.org>.
 *
 * Xenomai 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.
 *
 * Xenomai 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 Xenomai; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * \ingroup heap
 */

#ifndef _XENO_NUCLEUS_HEAP_H
#define _XENO_NUCLEUS_HEAP_H

#include <nucleus/queue.h>

/*
 * CONSTRAINTS:
 *
 * Minimum page size is 2 ** XNHEAP_MINLOG2 (must be large enough to
 * hold a pointer).
 *
 * Maximum page size is 2 ** XNHEAP_MAXLOG2.
 *
 * Minimum block size equals the minimum page size.
 *
 * Requested block size smaller than the minimum block size is
 * rounded to the minimum block size.
 *
 * Requested block size larger than 2 times the page size is rounded
 * to the next page boundary and obtained from the free page
 * list. So we need a bucket for each power of two between
 * XNHEAP_MINLOG2 and XNHEAP_MAXLOG2 inclusive, plus one to honor
 * requests ranging from the maximum page size to twice this size.
 */

#if defined(__KERNEL__) || defined(__XENO_SIM__)

#define XNHEAP_PAGE_SIZE        512 /* A reasonable value for the xnheap page size */
#define XNHEAP_PAGE_MASK        (~(XNHEAP_PAGE_SIZE-1))
#define XNHEAP_PAGE_ALIGN(addr) (((addr)+XNHEAP_PAGE_SIZE-1)&XNHEAP_PAGE_MASK)

#define XNHEAP_MINLOG2    3
#define XNHEAP_MAXLOG2    22    /* Must hold pagemap::bcount objects */
#define XNHEAP_MINALLOCSZ (1 << XNHEAP_MINLOG2)
#define XNHEAP_MINALIGNSZ (1 << 4) /* i.e. 16 bytes */
#define XNHEAP_NBUCKETS   (XNHEAP_MAXLOG2 - XNHEAP_MINLOG2 + 2)
#define XNHEAP_MAXEXTSZ   (1 << 31) /* i.e. 2Gb */

#define XNHEAP_PFREE   0
#define XNHEAP_PCONT   1
#define XNHEAP_PLIST   2

#define XNHEAP_GFP_NONCACHED (1 << __GFP_BITS_SHIFT)

struct xnpagemap {
        unsigned int type : 8;    /* PFREE, PCONT, PLIST or log2 */
        unsigned int bcount : 24; /* Number of active blocks. */
};

typedef struct xnextent {

        xnholder_t link;

#define link2extent(ln) container_of(ln, xnextent_t, link)

        caddr_t membase,        /* Base address of the page array */
                memlim,         /* Memory limit of page array */
                freelist;       /* Head of the free page list */

        struct xnpagemap pagemap[1];    /* Beginning of page map */

} xnextent_t;

typedef struct xnheap {

        xnholder_t link;

#define link2heap(ln)           container_of(ln, xnheap_t, link)

        u_long extentsize,
                pagesize,
                pageshift,
                hdrsize,
                npages,         /* Number of pages per extent */
                ubytes,
                maxcont;

        xnqueue_t extents;

        DECLARE_XNLOCK(lock);

        struct xnbucket {
                caddr_t freelist;
                int fcount;
        } buckets[XNHEAP_NBUCKETS];

        xnholder_t *idleq[XNARCH_NR_CPUS];

        xnarch_heapcb_t archdep;

        XNARCH_DECL_DISPLAY_CONTEXT();

        xnholder_t stat_link;   /* Link in heapq */

        char label[XNOBJECT_NAME_LEN+16];

} xnheap_t;

extern xnheap_t kheap;

#if CONFIG_XENO_OPT_SYS_STACKPOOLSZ > 0
extern xnheap_t kstacks;
#endif

#define xnheap_extentsize(heap)         ((heap)->extentsize)
#define xnheap_page_size(heap)          ((heap)->pagesize)
#define xnheap_page_count(heap)         ((heap)->npages)
#define xnheap_usable_mem(heap)         ((heap)->maxcont * countq(&(heap)->extents))
#define xnheap_used_mem(heap)           ((heap)->ubytes)
#define xnheap_max_contiguous(heap)     ((heap)->maxcont)

static inline size_t xnheap_align(size_t size, size_t al)
{
        /* The alignment value must be a power of 2 */
        return ((size+al-1)&(~(al-1)));
}

static inline size_t xnheap_external_overhead(size_t hsize, size_t psize)
{
        size_t pages = (hsize + psize - 1) / psize;
        return xnheap_align(sizeof(xnextent_t)
                            + pages * sizeof(struct xnpagemap), psize);
}

static inline size_t xnheap_internal_overhead(size_t hsize, size_t psize)
{
        /* o = (h - o) * m / p + e
           o * p = (h - o) * m + e * p
           o * (p + m) = h * m + e * p
           o = (h * m + e *p) / (p + m)
        */
        return xnheap_align((sizeof(xnextent_t) * psize
                             + sizeof(struct xnpagemap) * hsize)
                            / (psize + sizeof(struct xnpagemap)), psize);
}

#define xnmalloc(size)     xnheap_alloc(&kheap,size)
#define xnfree(ptr)        xnheap_free(&kheap,ptr)
#define xnfreesync()       xnheap_finalize_free(&kheap)
#define xnfreesafe(thread, ptr, ln)                             \
        do {                                                    \
                if (xnpod_current_p(thread))                    \
                        xnheap_schedule_free(&kheap, ptr, ln);  \
                else                                            \
                        xnheap_free(&kheap,ptr);                \
        } while(0)

static inline size_t xnheap_rounded_size(size_t hsize, size_t psize)
{
        /*
         * Account for the minimum heap size (i.e. 2 * page size) plus
         * overhead so that the actual heap space is large enough to
         * match the requested size. Using a small page size for large
         * single-block heaps might reserve a lot of useless page map
         * memory, but this should never get pathological anyway,
         * since we only consume 4 bytes per page.
         */
        if (hsize < 2 * psize)
                hsize = 2 * psize;
        hsize += xnheap_external_overhead(hsize, psize);
        return xnheap_align(hsize, psize);
}

#ifdef __cplusplus
extern "C" {
#endif

/* Private interface. */

#ifdef __KERNEL__

int xnheap_mount(void);

void xnheap_umount(void);

void xnheap_init_proc(void);

void xnheap_cleanup_proc(void);

int xnheap_init_mapped(xnheap_t *heap,
                       u_long heapsize,
                       int memflags);

void xnheap_destroy_mapped(xnheap_t *heap,
                           void (*release)(struct xnheap *heap),
                           void __user *mapaddr);

#define xnheap_base_memory(heap) \
        ((caddr_t)(heap)->archdep.heapbase)

#define xnheap_mapped_offset(heap,ptr) \
        (((caddr_t)(ptr)) - xnheap_base_memory(heap))

#define xnheap_mapped_address(heap,off) \
        (xnheap_base_memory(heap) + (off))

#define xnheap_mapped_p(heap) \
        (xnheap_base_memory(heap) != NULL)

#endif /* __KERNEL__ */

/* Public interface. */

int xnheap_init(xnheap_t *heap,
                void *heapaddr,
                u_long heapsize,
                u_long pagesize);

void xnheap_set_label(xnheap_t *heap, const char *name, ...);

void xnheap_destroy(xnheap_t *heap,
                    void (*flushfn)(xnheap_t *heap,
                                    void *extaddr,
                                    u_long extsize,
                                    void *cookie),
                    void *cookie);

int xnheap_extend(xnheap_t *heap,
                  void *extaddr,
                  u_long extsize);

void *xnheap_alloc(xnheap_t *heap,
                   u_long size);

int xnheap_test_and_free(xnheap_t *heap,
                         void *block,
                         int (*ckfn)(void *block));

int xnheap_free(xnheap_t *heap,
                void *block);

void xnheap_schedule_free(xnheap_t *heap,
                          void *block,
                          xnholder_t *link);

void xnheap_finalize_free_inner(xnheap_t *heap,
                                int cpu);

static inline void xnheap_finalize_free(xnheap_t *heap)
{
        int cpu = xnarch_current_cpu();

        XENO_ASSERT(NUCLEUS,
                    spltest() != 0,
                    xnpod_fatal("%s called in unsafe context", __FUNCTION__));

        if (heap->idleq[cpu])
                xnheap_finalize_free_inner(heap, cpu);
}

int xnheap_check_block(xnheap_t *heap,
                       void *block);

#ifdef __cplusplus
}
#endif

#endif /* __KERNEL__ || __XENO_SIM__ */

#define XNHEAP_DEV_NAME  "/dev/rtheap"
#define XNHEAP_DEV_MINOR 254

#ifdef CONFIG_MMU
/* XXX: 2.5.x ABI preserved for MMU-enabled only. */
#define xnheap_area_decl();
#define xnheap_area_set(p, val)
#else
#define xnheap_area_decl()      unsigned long area
#define xnheap_area_set(p, val) (p)->area = (unsigned long)(val)
#endif

struct xnheap_desc {
        unsigned long handle;
        unsigned int size;
        xnheap_area_decl();
};

#endif /* !_XENO_NUCLEUS_HEAP_H */

---