pmm.h

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// SPDX-License-Identifier: GPL-3.0-or-later
 
#pragma once
 
#include <mos/lib/structures/list.h>
#include <mos/mos_global.h>
#include <mos/types.h>
 
typedef struct phyframe phyframe_t;
 
// represents a physical frame, there will be one `phyframe_t` for each physical frame in the system
typedef struct phyframe
{
    enum phyframe_state
    {
        PHYFRAME_RESERVED = 0, // intentionally 0 (initially, all frames are reserved)
        PHYFRAME_FREE,
        PHYFRAME_ALLOCATED,
    } state;
 
    u8 order;
 
    union
    {
        MOS_WARNING_PUSH
        MOS_WARNING_DISABLE("-Wpedantic") // ISO C++ forbids anonymous structs
 
        struct // free frame
        {
            as_linked_list; // for use of freelist in the buddy allocator
        };
 
        struct
        {
            // for page cache frames
            bool dirty : 1; 
        } pagecache;
        MOS_WARNING_POP
    };
 
    union
    {
        // number of times this frame is mapped, if this drops to 0, the frame is freed
        atomic_t allocated_refcount;
    };
} phyframe_t;
 
MOS_STATIC_ASSERT(sizeof(phyframe_t) == 32, "update phyframe_t struct size");
 
typedef struct
{
    pfn_t pfn_start;
    size_t nframes;
    bool reserved;
    u32 type; // platform-specific type
} pmm_region_t;
 
typedef enum
{
    PMM_ALLOC_NORMAL = 0,
} pmm_allocation_flags_t;
 
extern phyframe_t *phyframes; // array of all physical frames
 
#define phyframe_pfn(frame) ((pfn_t) ((frame) - phyframes))
#define pfn_phyframe(pfn)   (&phyframes[(pfn)])
 
extern size_t pmm_total_frames, pmm_allocated_frames, pmm_reserved_frames;
 
void pmm_dump_lists(void);
 
void pmm_init();
 
phyframe_t *pmm_allocate_frames(size_t n_frames, pmm_allocation_flags_t flags);
void pmm_free_frames(phyframe_t *start_frame, size_t n_pages);
 
pfn_t pmm_reserve_frames(pfn_t pfn, size_t npages);
#define pmm_reserve_address(paddr)           pmm_reserve_frames(ALIGN_DOWN_TO_PAGE(paddr) / MOS_PAGE_SIZE, 1)
#define pmm_reserve_addresses(paddr, npages) pmm_reserve_frames(ALIGN_DOWN_TO_PAGE(paddr) / MOS_PAGE_SIZE, npages)
 
pmm_region_t *pmm_find_reserved_region(ptr_t needle);
 
// ! ref and unref frames
 
phyframe_t *_pmm_ref_phyframes(phyframe_t *frame, size_t npages);
void _pmm_unref_phyframes(phyframe_t *frame, size_t npages);
 
should_inline pfn_t _pmm_ref_pfn_range(pfn_t pfn_start, size_t npages)
{
    _pmm_ref_phyframes(pfn_phyframe(pfn_start), npages);
    return pfn_start;
}
 
should_inline void _pmm_unref_pfn_range(pfn_t pfn_start, size_t npages)
{
    _pmm_unref_phyframes(pfn_phyframe(pfn_start), npages);
}
 
#define pmm_ref(thing, npages)   _Generic((thing), phyframe_t *: _pmm_ref_phyframes, pfn_t: _pmm_ref_pfn_range)(thing, npages)
#define pmm_unref(thing, npages) _Generic((thing), phyframe_t *: _pmm_unref_phyframes, pfn_t: _pmm_unref_pfn_range)(thing, npages)
 
#define pmm_ref_one(thing)   pmm_ref(thing, 1)
#define pmm_unref_one(thing) pmm_unref(thing, 1)