Moved the loading of the elf program before the aquisition of most physical memory...

diff --git a/kernel/src/kernel.cpp b/kernel/src/kernel.cpp
index 2e4146e0f73bb1973285d74620a2ef313840daad..244eb1c9ec539aa7fe1290948f7c6dc09db611e6 100644 (file)
--- a/kernel/src/kernel.cpp
+++ b/kernel/src/kernel.cpp
@@ -24,6 +24,8 @@ extern "C" os::tss TSS;
 extern "C" char interrupt_stack_top;
 extern "C" os::paging::PML4T PML4T;
 
+os::paging::page bootstrap_pages_for_memory[32]; // 32 pages = 128 KiB
+
 extern "C" void kmain(unsigned long magic, os::phys_ptr<const multiboot2::info_start> info) {
        os::assert(magic == 0x36D76289, "Incorrect magic number: wasn't booted with multiboot2.");
        os::assert(os::cpu_has_msr(), "MSRs aren't supported.");
@@ -34,10 +36,20 @@ extern "C" void kmain(unsigned long magic, os::phys_ptr<const multiboot2::info_s
                }
        }
 
-       struct {
-               std::uint64_t start_address = 0;
-               std::uint64_t end_address = 0;
-       } test_module;
+       os::paging::page_allocator.deallocate({
+               .ptr = os::phys_ptr<os::paging::page>(reinterpret_cast<uintptr_t>(bootstrap_pages_for_memory) - 0xFFFF'FFFF'8000'0000),
+               .size = sizeof(bootstrap_pages_for_memory) / sizeof(bootstrap_pages_for_memory[0])
+       });
+
+       // Allocate this page so that I only ever need to update the mapping once when I create a new process or port.
+       {
+               const auto index = os::paging::calc_page_table_indices((void*)0xFFFF'C000'0000'0000).pml4e;
+               PML4T.contents[index] = {.P = 1, .R_W = 1, .U_S = 0, .PWT = 0, .PCD = 0, .base_address = 0, .NX = 0};
+               const auto PDPT_alloc = os::paging::page_allocator.allocate(1);
+               set_base_address(PML4T.contents[index], os::phys_ptr<os::paging::PDPT>(PDPT_alloc.ptr.get_phys_addr()));
+       }
+
+       os::process test_module_process = { nullptr, 0, 0 };
        {
                struct {
                        os::phys_ptr<os::paging::page> start_address = nullptr;
@@ -65,13 +77,18 @@ extern "C" void kmain(unsigned long magic, os::phys_ptr<const multiboot2::info_s
                                break;
                        case multiboot2::info::type_t::modules:
                                os::print("{}->{}: {}\n", multiboot2::modules_mod_start(it) / 0x1000 * 0x1000, multiboot2::modules_mod_end(it) / 0x1000 * 0x1000, multiboot2::modules_string(it));
-                               test_module.start_address = multiboot2::modules_mod_start(it);
-                               test_module.end_address   = multiboot2::modules_mod_end(it);
+                               os::assert(test_module_process.PML4T == nullptr, "Multiple modules specified in the multiboot. This is unsupported.");
+                               test_module_process =
+                                       os::elf::load_elf(&*os::phys_ptr<std::byte>(multiboot2::modules_mod_start(it)),
+                                                         multiboot2::modules_mod_end(it) - multiboot2::modules_mod_start(it),
+                                                         PML4T);
                                break;
                        default: break;
                        }
                }
 
+               os::assert(test_module_process.PML4T != nullptr, "No modules specified in the multiboot. This is unsupported.");
+
                // kernel_start and kernel_end are aligned to 4K by the linker script.
                const os::phys_ptr<os::paging::page> kernel_s = ([]() {
                        os::phys_ptr<os::paging::page> ptr = nullptr;
@@ -104,35 +121,8 @@ extern "C" void kmain(unsigned long magic, os::phys_ptr<const multiboot2::info_s
                                available_ram_length++;
                        }
                }
-               struct {
-                       os::phys_ptr<os::paging::page> start_address;
-                       os::phys_ptr<os::paging::page> end_address;
-               } test_module_block{
-                       os::phys_ptr<os::paging::page>(test_module.start_address / 0x1000 * 0x1000),
-                       os::phys_ptr<os::paging::page>(test_module.end_address / 0x1000 * 0x1000)
-               };
-               // Remove module from available RAM:
-               for (std::size_t i = 0; i < available_ram_length; i++) {
-                       if (test_module_block.end_address < available_ram[i].start_address || available_ram[i].end_address < test_module_block.start_address) {
-                               continue;
-                       }
-                       if (test_module_block.start_address <= available_ram[i].start_address && available_ram[i].end_address <= test_module_block.end_address) {
-                               available_ram[i] = available_ram[--available_ram_length];
-                               i--;
-                       } else if (test_module_block.start_address <= available_ram[i].start_address) {
-                               available_ram[i].start_address = test_module_block.end_address + 1; // Since e < end_address, new start_address <= end_address.
-                       } else if (available_ram[i].end_address <= test_module_block.end_address) {
-                               available_ram[i].end_address = test_module_block.start_address - 1; // Since start_address < s, start_address <= new end_address.
-                       } else {
-                               os::assert(available_ram_length < 50, "Too much available RAM sections to initialise correctly. Will fix eventually, probably.");
-                               available_ram[available_ram_length] = available_ram[i];
-                               available_ram[i].end_address = test_module_block.start_address - 1;
-                               available_ram[available_ram_length].start_address = test_module_block.end_address + 1;
-                               available_ram_length++;
-                       }
-               }
 
-               // Add available RAM to the page allocator (warning: overrides the multiboot info structure):
+               // Add available RAM to the page allocator (warning: overrides the multiboot info structure and the multiboot modules):
                for (std::size_t i = 0; i < available_ram_length; i++) {
                        os::paging::page_allocator.deallocate({
                                .ptr = available_ram[i].start_address,
@@ -186,17 +176,6 @@ extern "C" void kmain(unsigned long magic, os::phys_ptr<const multiboot2::info_s
        os::paging::page_allocator.deallocate({.ptr = os::phys_ptr<os::paging::page>(get_base_address(PML4T.contents[0]).get_phys_addr()), .size = 1});
        os::invlpg((void*)0x0);
 
-       // Allocate this page so that I only ever need to update the mapping once when I create a new process or port.
-       {
-               const auto index = os::paging::calc_page_table_indices((void*)0xFFFF'C000'0000'0000).pml4e;
-               PML4T.contents[index] = {.P = 1, .R_W = 1, .U_S = 0, .PWT = 0, .PCD = 0, .base_address = 0, .NX = 0};
-               const auto PDPT_alloc = os::paging::page_allocator.allocate(1);
-               set_base_address(PML4T.contents[index], os::phys_ptr<os::paging::PDPT>(PDPT_alloc.ptr.get_phys_addr()));
-       }
-
-       auto test_module_process =
-               os::elf::load_elf(&*os::phys_ptr<std::byte>(test_module.start_address), test_module.end_address - test_module.start_address, PML4T);
-
        os::print("Loading ring 3 interrupts stack.\n");
        os::set_ring0_stack(TSS, std::uint64_t(&interrupt_stack_top));
        os::print("Loading TSS.\n");