first commit

1 files changed, 212 insertions, 0 deletions

diff --git a/kernel/entry.cpp b/kernel/entry.cpp
new file mode 100644
index 0000000..c8f74c8
--- /dev/null
+++ b/kernel/entry.cpp
@@ -0,0 +1,212 @@
+#include <mercury/kernel/framebuffer.hpp>
+#include <mercury/kernel/terminal.hpp>
+#include <mercury/kernel/limine.hpp>
+#include <mercury/kernel/paging.hpp>
+
+using namespace mercury::kernel;
+
+LIMINE_BASE_REVISION(1)
+
+static volatile limine_memmap_request memmap_request {
+  .id = LIMINE_MEMMAP_REQUEST,
+  .revision = 0,
+  .response = 0
+};
+
+static volatile limine_kernel_address_request kernel_address_request {
+  .id = LIMINE_KERNEL_ADDRESS_REQUEST,
+  .revision = 0,
+  .response = 0
+};
+
+static volatile limine_framebuffer_request framebuffer_request {
+  .id = LIMINE_FRAMEBUFFER_REQUEST,
+  .revision = 0,
+  .response = 0
+};
+
+static volatile limine_hhdm_request hhdm_request {
+  .id = LIMINE_HHDM_REQUEST,
+  .revision = 0,
+  .response = 0
+};
+
+static limine_internal_module initfs_module = {
+  .path = "initfs.tgz",
+  .cmdline = "initfs",
+  .flags = LIMINE_INTERNAL_MODULE_REQUIRED | LIMINE_INTERNAL_MODULE_COMPRESSED
+};
+
+static limine_internal_module termfont_module = {
+  .path = "termfont.psf",
+  .cmdline = "termfont",
+  .flags = LIMINE_INTERNAL_MODULE_REQUIRED
+};
+
+static limine_internal_module *internal_modules[] = {
+  &initfs_module, &termfont_module
+};
+
+static volatile limine_module_request module_request = {
+  .id = LIMINE_MODULE_REQUEST,
+  .revision = 2,
+  .response = 0,
+  .internal_module_count = 2,
+  .internal_modules = internal_modules
+};
+
+bool try_map_module_by_cmdline(
+  const char *cmdline, void *&vaddr_out, uint64_t &len_out
+) {
+  auto response = module_request.response;
+  for (uint64_t i = 0; i < response->module_count; ++i) {
+    limine_file *file = response->modules[i];
+    for (uint64_t j = 0; cmdline[j] == file->cmdline[j]; ++j)
+      if (!cmdline[j]) {
+
+        //module start is guaranteed to be page-aligned, end is not.
+        uint64_t start_paddr =
+          (uint64_t)file->address - hhdm_request.response->offset;
+        uint64_t end_paddr =
+          ((start_paddr + file->size - 1) / 4096 + 1) * 4096;
+
+        uint64_t start_vaddr =
+          paging::find_unmapped_vram_region((end_paddr - start_paddr) / 4096);
+        for (uint64_t i = 0; i < end_paddr - start_paddr; i += 4096)
+          paging::map_kernel_page(
+            start_paddr + i, start_vaddr + i, true, false);
+
+        vaddr_out = (void *)start_vaddr;
+        len_out = file->size;
+
+        return true;
+      }
+  }
+  return false;
+}
+
+//defined in linker script, page-aligned:
+extern uint8_t __kernel_start;
+extern uint8_t __kernel_end;
+extern uint8_t __kernel_rx_start;
+extern uint8_t __kernel_rx_end;
+extern uint8_t __kernel_ro_start;
+extern uint8_t __kernel_ro_end;
+extern uint8_t __kernel_rw_start;
+extern uint8_t __kernel_rw_end;
+
+uint8_t *initfs;
+uint64_t initfs_len;
+
+[[noreturn]] static void with_kernel_p4();
+
+extern "C" [[noreturn]] void entry() {
+
+  //TODO?: maybe we should check if the limine requests were
+  //       fulfilled and display some error message if not
+
+  //set up the physical memory usage bitmap:
+
+  paging::mark_all_pram_used();
+  auto memmap = memmap_request.response;
+  for (uint64_t i = 0; i < memmap->entry_count; ++i) {
+    //we don't start allocating physical pages until after we are done using
+    //limine structures (specifically at the call to paging::map_kernel_stack),
+    //so we consider bootloader reclaimable to be free. usable and bootloader
+    //reclaimable are guaranteed by limine spec to be page-aligned.
+    auto entry = memmap->entries[i];
+    if (entry->type == LIMINE_MEMMAP_USABLE ||
+        entry->type == LIMINE_MEMMAP_BOOTLOADER_RECLAIMABLE)
+      paging::mark_pram_region_free(entry->base, entry->base + entry->length);
+  }
+
+  //set up page mappings:
+
+  auto kernel_address = kernel_address_request.response;
+  uint64_t kernel_offset = kernel_address->virtual_base
+                         - kernel_address->physical_base;
+
+  uint64_t hhdm = hhdm_request.response->offset;
+
+  //framebuffer might not be page-aligned
+  auto framebuffer = framebuffer_request.response->framebuffers[0];
+  uint64_t fb_start = ((uint64_t)framebuffer->address / 4096) * 4096 - hhdm;
+  uint64_t fb_end = (uint64_t)framebuffer->address
+                  + framebuffer->pitch * framebuffer->height - hhdm;
+  fb_end = ((fb_end - 1) / 4096 + 1) * 4096;
+
+  paging::init_kernel_page_tables(kernel_offset);
+
+  //kernel image rx
+  for (uint64_t vaddr = (uint64_t)&__kernel_rx_start;
+       vaddr < (uint64_t)&__kernel_rx_end; vaddr += 4096)
+    paging::map_kernel_page(vaddr - kernel_offset, vaddr, false, true);
+
+  //kernel image ro
+  for (uint64_t vaddr = (uint64_t)&__kernel_ro_start;
+       vaddr < (uint64_t)&__kernel_ro_end; vaddr += 4096)
+    paging::map_kernel_page(vaddr - kernel_offset, vaddr, false, false);
+
+  //kernel image rw
+  for (uint64_t vaddr = (uint64_t)&__kernel_rw_start;
+       vaddr < (uint64_t)&__kernel_rw_end; vaddr += 4096)
+    paging::map_kernel_page(vaddr - kernel_offset, vaddr, true, false);
+
+  //framebuffer
+  uint64_t fb_vaddr =
+    paging::find_unmapped_vram_region((fb_end - fb_start) / 4096);
+  for (uint64_t i = 0; i < fb_end - fb_start; i += 4096)
+    paging::map_kernel_page(fb_start + i, fb_vaddr + i, true, false);
+
+  //initfs and termfont - these are required modules
+  //so there is no worry about them not being present.
+  try_map_module_by_cmdline("initfs", (void *&)initfs, initfs_len);
+  try_map_module_by_cmdline(
+    "termfont", (void *&)terminal::termfont, terminal::termfont_len);
+
+  //set up framebuffer and terminal:
+  //TODO: assumes framebuffer is 32-bpp rgb
+
+  framebuffer::init_framebuffer(
+    fb_vaddr, framebuffer->width, framebuffer->height, framebuffer->pitch);
+
+  //switch to kernel p4
+
+  paging::map_kernel_stack();
+  switch_to_kernel_p4(&with_kernel_p4);
+
+}
+
+[[noreturn]] static void with_kernel_p4() {
+
+  terminal::init_terminal();
+  terminal::put_string_sz("kernel initialization complete.\n");
+
+  int used_vram_kib = paging::get_used_vram_page_count() * 4;
+  int free_pram_kib = paging::get_free_pram_page_count() * 4;
+
+  terminal::put_int_decimal(used_vram_kib);
+  terminal::put_string_sz(" kiB kernel memory mapped.\n");
+  terminal::put_int_decimal(free_pram_kib);
+  terminal::put_string_sz(" kiB physical memory free.\n");
+
+  terminal::put_string_sz("initfs first sector:");
+  for (int y = 0; y < 8; ++y) {
+    terminal::put_string_sz("\n  ");
+    for (int x = 0; x < 64; ++x)
+      terminal::put_char((char)initfs[y * 64 + x]);
+  }
+
+  terminal::put_string_sz("\ninitfs second sector:");
+  for (int y = 0; y < 8; ++y) {
+    terminal::put_string_sz("\n  ");
+    for (int x = 0; x < 64; ++x)
+      terminal::put_char((char)initfs[512 + y * 64 + x]);
+  }
+
+  while (1)
+    ;
+
+  //TODO
+
+}