Source/bmalloc/libpas/src/libpas/pas_bitfit_page.h

/*
 * Copyright (c) 2020-2021 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef PAS_BITFIT_PAGE_H
#define PAS_BITFIT_PAGE_H

#include "pas_bitfit_page_config.h"
#include "pas_compact_atomic_bitfit_view_ptr.h"
#include "pas_lock.h"
#include "pas_page_base.h"

PAS_BEGIN_EXTERN_C;

struct pas_bitfit_page;
typedef struct pas_bitfit_page pas_bitfit_page;

struct pas_bitfit_page {
    pas_page_base base;

    /* Tells us if we've told the directory that something was freed. If true, we ignore freeing.
       If false, we tell the directory that the page may have any amount of free bytes. The
       allocator will lazily figure out exactly how many free bytes later. */
    bool did_note_max_free;

    /* This is a source of truth - for example, we may have a view that says that the page is
       empty but this says it's not. */
    uint16_t num_live_bits;

    pas_compact_atomic_bitfit_view_ptr owner;

    uint64_t use_epoch;

    uint64_t bits[1]; /* This gets accessed in a crazy way. */
};

#define PAS_BITFIT_PAGE_BASE_HEADER_SIZE PAS_OFFSETOF(pas_bitfit_page, bits)

#define PAS_BITFIT_PAGE_HEADER_SIZE(page_size, granule_size, min_align_shift) \
    (PAS_BITFIT_PAGE_BASE_HEADER_SIZE + \
     PAS_ROUND_UP_TO_POWER_OF_2( \
         PAS_BITFIT_PAGE_CONFIG_NUM_ALLOC_BIT_BYTES(page_size, min_align_shift) + \
         PAS_PAGE_BASE_CONFIG_NUM_GRANULE_BYTES(page_size / granule_size), \
         sizeof(uint64_t)))

static PAS_ALWAYS_INLINE size_t pas_bitfit_page_header_size(pas_bitfit_page_config page_config)
{
    return PAS_BITFIT_PAGE_HEADER_SIZE(page_config.base.page_size,
                                       page_config.base.granule_size,
                                       page_config.base.min_align_shift);
}

static inline unsigned* pas_bitfit_page_free_bits(pas_bitfit_page* page)
{
    return (unsigned*)page->bits;
}

static PAS_ALWAYS_INLINE unsigned* pas_bitfit_page_object_end_bits(pas_bitfit_page* page,
                                                                   pas_bitfit_page_config page_config)
{
    return (unsigned*)(
        (char*)page->bits + pas_bitfit_page_config_byte_offset_for_object_bits(page_config));
}

static PAS_ALWAYS_INLINE pas_page_granule_use_count*
pas_bitfit_page_get_granule_use_counts(pas_bitfit_page* page,
                                       pas_bitfit_page_config page_config)
{
    PAS_ASSERT(page_config.base.page_size > page_config.base.granule_size);
    return (pas_page_granule_use_count*)(
        (char*)page->bits + pas_bitfit_page_config_num_alloc_bit_bytes(page_config));
}

PAS_API void pas_bitfit_page_construct(pas_bitfit_page* page,
                                       pas_bitfit_view* view,
                                       pas_bitfit_page_config* config);

static PAS_ALWAYS_INLINE uintptr_t
pas_bitfit_page_offset_to_first_object(pas_bitfit_page_config page_config)
{
    return pas_round_up_to_power_of_2(page_config.base.page_object_payload_offset,
                                      pas_page_base_config_min_align(page_config.base));
}

static PAS_ALWAYS_INLINE uintptr_t
pas_bitfit_page_offset_to_end_of_last_object(pas_bitfit_page_config page_config)
{
    return pas_round_down_to_power_of_2(
        pas_page_base_config_object_payload_end_offset_from_boundary(page_config.base),
        pas_page_base_config_min_align(page_config.base));
}

static PAS_ALWAYS_INLINE size_t
pas_bitfit_page_payload_size(pas_bitfit_page_config page_config)
{
    uintptr_t first_object;
    uintptr_t end_of_last_object;

    first_object = pas_bitfit_page_offset_to_first_object(page_config);
    end_of_last_object = pas_bitfit_page_offset_to_end_of_last_object(page_config);
    
    PAS_ASSERT(first_object < end_of_last_object);

    return end_of_last_object - first_object;
}

static PAS_ALWAYS_INLINE pas_bitfit_page*
pas_bitfit_page_for_boundary(void* boundary,
                             pas_bitfit_page_config page_config)
{
    return pas_page_base_get_bitfit(pas_page_base_for_boundary(boundary, page_config.base));
}

static PAS_ALWAYS_INLINE pas_bitfit_page*
pas_bitfit_page_for_boundary_or_null(void* boundary,
                                     pas_bitfit_page_config page_config)
{
    return pas_page_base_get_bitfit(pas_page_base_for_boundary_or_null(boundary, page_config.base));
}

static PAS_ALWAYS_INLINE pas_bitfit_page*
pas_bitfit_page_for_boundary_unchecked(void* boundary,
                                       pas_bitfit_page_config page_config)
{
    return (pas_bitfit_page*)pas_page_base_for_boundary(boundary, page_config.base);
}

static PAS_ALWAYS_INLINE void* pas_bitfit_page_boundary(pas_bitfit_page* page,
                                                        pas_bitfit_page_config page_config)
{
    return pas_page_base_boundary(&page->base, page_config.base);
}

static PAS_ALWAYS_INLINE void* pas_bitfit_page_boundary_or_null(pas_bitfit_page* page,
                                                                pas_bitfit_page_config page_config)
{
    return pas_page_base_boundary_or_null(&page->base, page_config.base);
}

static PAS_ALWAYS_INLINE pas_bitfit_page*
pas_bitfit_page_for_address_and_page_config(uintptr_t begin,
                                            pas_bitfit_page_config page_config)
{
    return pas_page_base_get_bitfit(
        pas_page_base_for_address_and_page_config(begin, page_config.base));
}

PAS_API pas_bitfit_page_config* pas_bitfit_page_get_config(pas_bitfit_page* page);

PAS_API void pas_bitfit_page_log_bits(
    pas_bitfit_page* page, uintptr_t mark_begin_offset, uintptr_t mark_end_offset);

PAS_API PAS_NO_RETURN void pas_bitfit_page_deallocation_did_fail(
    pas_bitfit_page* page,
    pas_bitfit_page_config_kind config_kind,
    uintptr_t begin,
    uintptr_t offset,
    const char* reason);

typedef bool (*pas_bitfit_page_for_each_live_object_callback)(
    uintptr_t begin,
    size_t size,
    void* arg);

PAS_API bool pas_bitfit_page_for_each_live_object(
    pas_bitfit_page* page,
    pas_bitfit_page_for_each_live_object_callback callback,
    void* arg);

PAS_API void pas_bitfit_page_verify(pas_bitfit_page* page);

static inline void pas_bitfit_page_testing_verify(pas_bitfit_page* page)
{
    if (PAS_ENABLE_TESTING)
        pas_bitfit_page_verify(page);
}

PAS_END_EXTERN_C;

#endif /* PAS_BITFIT_PAGE_H */