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[boot][kernel] Replace frame allocator with bitmap-based one

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The previous frame allocator involved a lot of splitting and merging
linked lists and lost all information about frames while they were
allocated. The new allocator is based on an array of descriptor
structures and a bitmap. Each memory map region of allocatable memory
becomes one or more descriptors, each mapping up to 1GiB of physical
memory. The descriptors implement two levels of a bitmap tree, and have
a pointer into the large contiguous bitmap to track individual pages.
This commit is contained in:
Justin C. Miller
2021-01-22 00:16:01 -08:00
parent fd8552ca3a
commit aae18fd035
14 changed files with 419 additions and 212 deletions
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42
src/boot/paging.cpp
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@@ -212,6 +212,7 @@ allocate_tables(kernel::args::header *args, uefi::boot_services *bs)
page_table *pml4 = reinterpret_cast<page_table*>(addr);
args->pml4 = pml4;
args->table_pages = tables_needed;
args->table_count = tables_needed - 1;
args->page_tables = offset_ptr<void>(addr, page_size);
@@ -220,7 +221,7 @@ allocate_tables(kernel::args::header *args, uefi::boot_services *bs)
add_kernel_pds(pml4, args->page_tables, args->table_count);
add_offset_mappings(pml4, args->page_tables, args->table_count);
console::print(L" Set up initial mappings, %d spare tables.\r\n", args->table_count);
//console::print(L" Set up initial mappings, %d spare tables.\r\n", args->table_count);
}
template <typename E>
@@ -231,32 +232,31 @@ constexpr bool has_flag(E set, E flag) {
}
void
map_section(
map_pages(
kernel::args::header *args,
const kernel::args::program_section &section)
uintptr_t phys, uintptr_t virt,
size_t count, bool write_flag, bool exe_flag)
{
if (!count)
return;
paging::page_table *pml4 =
reinterpret_cast<paging::page_table*>(args->pml4);
size_t pages = memory::bytes_to_pages(section.size);
page_entry_iterator<4> iterator{
section.virt_addr, pml4,
virt, pml4,
args->page_tables,
args->table_count};
using kernel::args::section_flags;
uint64_t flags = page_flags;
if (!has_flag(section.type, section_flags::execute))
if (!exe_flag)
flags |= (1ull << 63); // set NX bit
if (has_flag(section.type, section_flags::write))
if (write_flag)
flags |= 2;
uintptr_t phys = section.phys_addr;
while (true) {
*iterator = phys | flags;
if (--pages == 0)
if (--count == 0)
break;
iterator.increment();
@@ -264,6 +264,24 @@ map_section(
}
}
void
map_section(
kernel::args::header *args,
const kernel::args::program_section &section)
{
using kernel::args::section_flags;
size_t pages = memory::bytes_to_pages(section.size);
map_pages(
args,
section.phys_addr,
section.virt_addr,
pages,
has_flag(section.type, section_flags::write),
has_flag(section.type, section_flags::execute));
}
} // namespace paging
} // namespace boot