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[boot] Virtualize memory in the bootloader

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Finish updating the page tables, call UEFI's `set_virtual_address_map`
and jump to the kernel!
This commit is contained in:
Justin C. Miller
2020-05-21 23:49:49 -07:00
parent 6a538ad4f3
commit b491a09686
6 changed files with 89 additions and 74 deletions
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70
src/boot/memory.cpp
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@@ -1,9 +1,12 @@
#include <stddef.h>
#include <uefi/types.h>
#include "kernel_memory.h"
#include "console.h"
#include "error.h"
#include "memory.h"
#include "paging.h"
namespace boot {
namespace memory {
@@ -85,51 +88,6 @@ mark_pointer_fixup(void **p)
fixup_pointers[fixup_pointer_index++] = p;
}
/*
void
virtualize(paging::page_table *pml4, uefi::runtime_services *rs, efi_mem_map *map)
{
// Get the pointer to the start of PML4
uint64_t* cr3 = 0;
__asm__ __volatile__ ( "mov %%cr3, %0" : "=r" (cr3) );
// PML4 is indexed with bits 39:47 of the virtual address
uint64_t offset = (KERNEL_VIRT_ADDRESS >> 39) & 0x1ff;
// Double map the lower half pages that are present into the higher half
for (unsigned i = 0; i < offset; ++i) {
if (cr3[i] & 0x1)
new_pml4[i] = new_pml4[offset+i] = cr3[i];
else
new_pml4[i] = new_pml4[offset+i] = 0;
}
// Write our new PML4 pointer back to CR3
__asm__ __volatile__ ( "mov %0, %%cr3" :: "r" (new_pml4) );
EFI_MEMORY_DESCRIPTOR *end = INCREMENT_DESC(map->entries, map->length);
EFI_MEMORY_DESCRIPTOR *d = map->entries;
while (d < end) {
switch (d->Type) {
case memtype_kernel:
case memtype_data:
case memtype_initrd:
case memtype_scratch:
d->Attribute |= EFI_MEMORY_RUNTIME;
d->VirtualStart = d->PhysicalStart + KERNEL_VIRT_ADDRESS;
default:
if (d->Attribute & EFI_MEMORY_RUNTIME) {
d->VirtualStart = d->PhysicalStart + KERNEL_VIRT_ADDRESS;
}
}
d = INCREMENT_DESC(d, map->size);
}
runsvc->SetVirtualAddressMap(map->length, map->size, map->version, map->entries);
}
*/
bool
can_merge(mem_entry &prev, mem_type type, uefi::memory_descriptor *next)
{
@@ -165,7 +123,7 @@ get_uefi_mappings(efi_mem_map *map, bool allocate, uefi::boot_services *bs)
}
}
size_t
efi_mem_map
build_kernel_mem_map(kernel::args::header *args, uefi::boot_services *bs)
{
status_line(L"Creating kernel memory map");
@@ -286,7 +244,25 @@ build_kernel_mem_map(kernel::args::header *args, uefi::boot_services *bs)
}
*/
return efi_map.key;
return efi_map;
}
void
virtualize(void *pml4, efi_mem_map &map, uefi::runtime_services *rs)
{
paging::add_current_mappings(reinterpret_cast<paging::page_table*>(pml4));
for (auto desc : map)
desc->virtual_start = desc->physical_start + ::memory::page_offset;
// Write our new PML4 pointer to CR3
asm volatile ( "mov %0, %%cr3" :: "r" (pml4) );
__sync_synchronize();
try_or_raise(
rs->set_virtual_address_map(
map.length, map.size, map.version, map.entries),
L"Error setting virtual address map");
}