palloc.c File Reference

#include <stdbool.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/kassert.h>
#include <sys/kdebug.h>
#include <sys/kmem.h>
#include <sys/queue.h>
#include <sys/spinlock.h>
#include <machine/amd64.h>
#include <machine/pmap.h>

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Data Structures
struct	FreePage
struct	PageInfo

Macros
#define	FREEPAGE_MAGIC_FREE   0x4652454550414745ULL
#define	FREEPAGE_MAGIC_INUSE   0x414c4c4f43415445ULL

Typedefs
typedef struct FreePage	FreePage
typedef struct PageInfo	PageInfo

Functions
	LIST_HEAD (FreeListHead, FreePage)
void	PAlloc_LateInit ()
void	PAlloc_AddRegion (uintptr_t start, uintptr_t len)
static PageInfo *	PAllocGetInfo (void *pg)
void *	PAlloc_AllocPage ()
static void	PAllocFreePage (void *region)
void	PAlloc_Retain (void *pg)
void	PAlloc_Release (void *pg)
static void	Debug_PAllocStats (int argc, const char *argv[])
	REGISTER_DBGCMD (pallocstats, "Page allocator statistics", Debug_PAllocStats)
static void	Debug_PAllocDump (int argc, const char *argv[])
	REGISTER_DBGCMD (pallocdump, "Dump page allocator's free list", Debug_PAllocDump)

Variables
Spinlock	pallocLock
uint64_t	totalPages
uint64_t	freePages
XMem *	pageInfoXMem
PageInfo *	pageInfoTable
uint64_t	pageInfoLength

---

Data Structure Documentation

FreePage

struct FreePage

Definition at line 31 of file palloc.c.

Collaboration diagram for FreePage:

Data Fields
uint64_t	magic

PageInfo

struct PageInfo

Definition at line 37 of file palloc.c.

Collaboration diagram for PageInfo:

Data Fields
uint64_t	refCount

Macro Definition Documentation

FREEPAGE_MAGIC_FREE

#define FREEPAGE_MAGIC_FREE   0x4652454550414745ULL

Definition at line 23 of file palloc.c.

FREEPAGE_MAGIC_INUSE

#define FREEPAGE_MAGIC_INUSE   0x414c4c4f43415445ULL

Definition at line 25 of file palloc.c.

Typedef Documentation

FreePage

typedef struct FreePage FreePage

PageInfo

typedef struct PageInfo PageInfo

Function Documentation

Debug_PAllocDump()

static void Debug_PAllocDump ( int  argc, const char *  argv[]  )

static

Definition at line 288 of file palloc.c.

{
    struct FreePage *it;
 
    LIST_FOREACH(it, &freeList, entries) {
        if (it->magic != FREEPAGE_MAGIC_FREE)
            kprintf("Magic Corrupted! (%lx)\n", it->magic);
        kprintf("Free %lx\n", (uintptr_t)it);
    }
}

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Debug_PAllocStats()

static void Debug_PAllocStats ( int  argc, const char *  argv[]  )

static

Definition at line 278 of file palloc.c.

{
    kprintf("Total Pages: %llu\n", totalPages);
    kprintf("Allocated Pages: %llu\n", totalPages - freePages);
    kprintf("Free Pages: %llu\n", freePages);
}

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LIST_HEAD()

LIST_HEAD	(	FreeListHead	,
		FreePage
	)

Definition at line 45 of file palloc.c.

{
    totalPages = 0;
    freePages = 0;
 
    Spinlock_Init(&pallocLock, "PAlloc Lock", SPINLOCK_TYPE_NORMAL);
 
    LIST_INIT(&freeList);
    pageInfoXMem = NULL;
    pageInfoTable = NULL;
}

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PAlloc_AddRegion()

void PAlloc_AddRegion	(	uintptr_t	start,
		uintptr_t	len
	)

PAlloc_AddRegion –

Add a physical memory region to the page allocator.

Definition at line 92 of file palloc.c.

{
    uintptr_t i;
    FreePage *pg;
 
    if ((start % PGSIZE) != 0)
        Panic("Region start is not page aligned!");
    if ((len % PGSIZE) != 0)
        Panic("Region length is not page aligned!");
 
    /*
     * PageInfo table isn't initialized on the first call to this function.  We 
     * must allocate a temporary table that will be copied into the XMem region 
     * inside PAlloc_LateInit.
     *
     * Note that the PageInfo table is invalid for regions that are not added 
     * to the free list such as MMIO regions.
     */
    if (pageInfoTable == NULL) {
        // Physical Address Offsets
        uintptr_t base = (uintptr_t)DMVA2PA(start);
        uintptr_t end = base + len;
 
        pageInfoLength = ROUNDUP(end / PGSIZE * sizeof(PageInfo), PGSIZE);
        pageInfoTable = (PageInfo *)start;
 
        start += pageInfoLength;
        len -= pageInfoLength;
 
        for (i = 0; i < (base / PGSIZE); i++) {
            pageInfoTable[i].refCount = 1;
        }
        for (i = (base / PGSIZE); i < (end / PGSIZE); i++) {
            pageInfoTable[i].refCount = 0;
        }
        for (i = 0; i < (pageInfoLength / PGSIZE); i++) {
            pageInfoTable[i + (base / PGSIZE)].refCount = 1;
        }
    } else {
        /*
         * Only the first call to AddRegion should occur before the XMem region 
         * is initialized.
         */
        
        ASSERT(pageInfoXMem != NULL);
 
        uintptr_t base = (uintptr_t)DMVA2PA(start);
        uintptr_t end = base + len;
 
        uintptr_t newLength = ROUNDUP(end / PGSIZE * sizeof(PageInfo), PGSIZE);
 
        if (!XMem_Allocate(pageInfoXMem, newLength))
            Panic("Cannot allocate XMem region!");
 
        // Initialize new pages
        for (i = (base / PGSIZE); i < (end / PGSIZE); i++) {
            pageInfoTable[i].refCount = 0;
        }
    }
 
    Spinlock_Lock(&pallocLock);
    for (i = 0; i < len; i += PGSIZE)
    {
        pg = (void *)(start + i);
        pg->magic = FREEPAGE_MAGIC_FREE;
 
        totalPages++;
        freePages++;
 
        LIST_INSERT_HEAD(&freeList, pg, entries);
    }
    Spinlock_Unlock(&pallocLock);
}

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PAlloc_AllocPage()

void * PAlloc_AllocPage

(

)

PAlloc_AllocPage –

Allocate a physical page and return the page's address in the Kernel's ident mapped memory region.

Return values

NULL	if no memory is available.

Returns

Newly allocated physical page.

Definition at line 188 of file palloc.c.

{
    PageInfo *info;
    FreePage *pg;
 
    Spinlock_Lock(&pallocLock);
    pg = LIST_FIRST(&freeList);
    ASSERT(pg != NULL);
    LIST_REMOVE(pg, entries);
 
    ASSERT(pg->magic == FREEPAGE_MAGIC_FREE);
 
    info = PAllocGetInfo(pg);
    ASSERT(info != NULL);
    ASSERT(info->refCount == 0);
    info->refCount++;
 
    pg->magic = FREEPAGE_MAGIC_INUSE;
 
    freePages--;
    Spinlock_Unlock(&pallocLock);
 
    memset(pg, 0, PGSIZE);
 
    return (void *)pg;
}

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PAlloc_LateInit()

void PAlloc_LateInit

(

)

PAlloc_LateInit –

The late init call is made after the page tables are initialized using a small boot memory region (2nd 16MBs). This is where initialize the XMem region that represents the PageInfo array, and map memory into it.

Definition at line 71 of file palloc.c.

{
    void *pageInfoOld = pageInfoTable;
 
    pageInfoXMem = XMem_New();
    if (!XMem_Allocate(pageInfoXMem, pageInfoLength)) {
        Panic("Cannot back pageInfoTable!");
    }
 
    pageInfoTable = (PageInfo *)XMem_GetBase(pageInfoXMem);
    memcpy(pageInfoTable, pageInfoOld, pageInfoLength);
 
    // Free old pages
}

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PAlloc_Release()

void PAlloc_Release

(

void *

pg

)

PAlloc_Release –

Deccrement the reference count for a physical page. If the reference count is zero the page will be freed.

Definition at line 265 of file palloc.c.

{
    PageInfo *info = PAllocGetInfo(pg);
 
    Spinlock_Lock(&pallocLock);
    ASSERT(info->refCount != 0);
    info->refCount--;
    if (info->refCount == 0)
        PAllocFreePage(pg);
    Spinlock_Unlock(&pallocLock);
}

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PAlloc_Retain()

void PAlloc_Retain

(

void *

pg

)

PAlloc_Retain –

Increment the reference count for a physical page.

Definition at line 248 of file palloc.c.

{
    PageInfo *info = PAllocGetInfo(pg);
 
    Spinlock_Lock(&pallocLock);
    ASSERT(info->refCount != 0);
    info->refCount++;
    Spinlock_Unlock(&pallocLock);
}

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PAllocFreePage()

static void PAllocFreePage ( void *  region )

static

PAllocFreePage –

Free a page.

Definition at line 221 of file palloc.c.

{
    FreePage *pg = (FreePage *)region;
 
    ASSERT(((uintptr_t)region % PGSIZE) == 0);
 
    LIST_INSERT_HEAD(&freeList, pg, entries);
 
#ifndef NDEBUG
    // Application can write this magic, but for
    // debug builds we can use this as a double free check.
    ASSERT(pg->magic != FREEPAGE_MAGIC_FREE);
 
    PageInfo *info = PAllocGetInfo(pg);
    ASSERT(info->refCount == 0);
#endif
 
    pg->magic = FREEPAGE_MAGIC_FREE;
    freePages++;
}

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PAllocGetInfo()

static PageInfo * PAllocGetInfo ( void *  pg )

inlinestatic

PAllocGetInfo –

Lookup the PageInfo structure for a given physical address.

Definition at line 172 of file palloc.c.

{
    uintptr_t entry = (uintptr_t)DMVA2PA(pg) / PGSIZE;
    return &pageInfoTable[entry];
}

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REGISTER_DBGCMD() [1/2]

REGISTER_DBGCMD	(	pallocdump	,
		"Dump page allocator's free list"	,
		Debug_PAllocDump
	)

REGISTER_DBGCMD() [2/2]

REGISTER_DBGCMD	(	pallocstats	,
		"Page allocator statistics"	,
		Debug_PAllocStats
	)

Variable Documentation

freePages

uint64_t freePages

Definition at line 29 of file palloc.c.

pageInfoLength

uint64_t pageInfoLength

Definition at line 44 of file palloc.c.

pageInfoTable

PageInfo* pageInfoTable

Definition at line 43 of file palloc.c.

pageInfoXMem

XMem* pageInfoXMem

Definition at line 42 of file palloc.c.

pallocLock

Spinlock pallocLock

Definition at line 27 of file palloc.c.

totalPages

uint64_t totalPages

Definition at line 28 of file palloc.c.