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Reclaim bootloader page table pages

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josh committed 2022-11-06 21:59:42 -05:00
1 parent b3fb599b25
commit 71c30fa932
4 files changed
+153 -90
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src/hulk/hippo.d
+20 -82
View File
@@ -1,20 +1,18 @@
/**
* HIPPO, the HOS In-place Physical Page Organizer.
*
* HIPPO maintains a list of free physical pages "in place", meaning that the
* available page itself is used as the linked list entry so separate memory
* is not needed to keep track of the available pages.
*/
module hulk.hippo;
import hulk.header;
import hulk.bootinfo;
import hulk.klog;
import hulk.linker_addresses;
import hulk.pagetable;
struct hippo
{
/**
* Linked list node entry for a physical page.
*/
private struct PhysicalPage
private static struct PhysicalPage
{
PhysicalPage * next;
}
@@ -27,96 +25,25 @@ struct hippo
/**
* Number of free physical pages.
*/
private static __gshared size_t n_free_pages;
/**
* Physical address limit.
*/
public static __gshared size_t physical_address_limit;
/**
* Initialize HIPPO.
*
* Ok, what we do here is iterate through all of the memory map regions in
* the bootinfo memory_map array, and create a linked list of all free
* physical pages that are available. Within the available memory regions,
* we have to watch out for the following items:
* 1) HULK binary (text + data)
* - This includes the HULK header and bootinfo structures
* 2) HULK bss
* 3) HULK stack
* 4) Framebuffer
* 5) Page tables
*
* @param bootinfo HULK boot information structure.
*/
public static void initialize(HulkHeader * header)
{
size_t usable_memory;
ulong[2][4] reserved = [
[header.bootinfo.hulk_phys, LinkerAddresses.hulk_binary_size],
[header.bootinfo.bss_phys, LinkerAddresses.hulk_bss_size],
[header.bootinfo.stack_phys, header.stack_size],
[cast(ulong)header.bootinfo.fb.buffer, header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u],
];
for (size_t ri = 0u; ri < reserved.length; ri++)
{
reserved[ri][1] += reserved[ri][0];
}
for (size_t bii = 0u; bii < header.bootinfo.memory_map_count; bii++)
{
if ((header.bootinfo.memory_map[bii].type == BootInfo.MemoryRegion.Type.Bootloader) ||
(header.bootinfo.memory_map[bii].type == BootInfo.MemoryRegion.Type.Conventional))
{
ulong phys = header.bootinfo.memory_map[bii].base;
ulong phys_end = phys + header.bootinfo.memory_map[bii].size;
if (phys_end > physical_address_limit)
{
physical_address_limit = phys_end;
}
usable_memory += header.bootinfo.memory_map[bii].size;
while (phys < phys_end)
{
bool is_reserved = false;
for (size_t ri = 0u; ri < reserved.length; ri++)
{
if ((reserved[ri][0] <= phys) && (phys < reserved[ri][1]))
{
is_reserved = true;
break;
}
}
if (!is_reserved)
{
free_page(phys);
}
phys += PAGE_SIZE;
}
}
}
size_t usable_kb = usable_memory >> 10u;
size_t usable_mb = usable_kb >> 10u;
size_t frac_mb = ((1000u * (usable_kb & 0x3FFu)) + 512u) >> 10u;
klog.writefln("Found %u.%03uMB of usable RAM", usable_mb, frac_mb);
}
private static __gshared size_t m_n_free_pages;
/**
* Free a physical page.
*
* @param phys Physical page address.
*/
private static void free_page(ulong phys)
public static void free_page(T)(T phys)
{
PhysicalPage * pp = cast(PhysicalPage *)phys;
pp.next = free_pages;
free_pages = pp;
n_free_pages++;
m_n_free_pages++;
}
/**
* Allocate a physical page.
*
* @return Page address, or null if none available.
* @return Page address, or null if no pages are available.
*/
public static void * allocate_page()
{
@@ -125,7 +52,18 @@ struct hippo
{
pp = free_pages;
free_pages = free_pages.next;
m_n_free_pages--;
}
return cast(void *)pp;
}
/**
* Get the number of free pages.
*
* @return The number of free pages.
*/
public @property size_t n_free_pages() const
{
return m_n_free_pages;
}
}