rewrite application stuff in the kernel to support multitasking

1 files changed, 189 insertions, 0 deletions

diff --git a/kernel/source/app-memory.cpp b/kernel/source/app-memory.cpp
new file mode 100644
index 0000000..cca1359
--- /dev/null
+++ b/kernel/source/app-memory.cpp
@@ -0,0 +1,189 @@
+#include <hilbert/kernel/app-memory.hpp>
+#include <hilbert/kernel/paging.hpp>
+#include <hilbert/kernel/panic.hpp>
+
+namespace hilbert::kernel {
+
+  app_memory::app_memory() {
+
+    uint64_t p3_paddr;
+    paging::map_new_kernel_page(p3, p3_paddr);
+    paging::map_new_kernel_page(p4, p4_paddr);
+
+    for (int i = 0; i < 512; ++i) {
+      p4[i] = 0;
+      p3[i] = 0;
+      p2s[i] = 0;
+      p1s[i] = 0;
+      pram_pages_to_free_on_exit[i] = 0;
+    }
+
+    p4[0] = paging::encode_pte(p3_paddr, true, true, true);
+    p4[511] = paging::kernel_p4e;
+
+  }
+
+  app_memory::~app_memory() {
+
+    //first we see if the p2s exist
+    for (int p3i = 0; p3i < 512; ++p3i)
+      if (p3[p3i]) {
+
+        //now we see if the p1s under this p2 exist
+        for (int p2i = 0; p2i < 512; ++p2i)
+          if (p2s[p3i][p2i]) {
+
+            //we see if the pages under this p1 need to be freed
+            for (int p1i = 0; p1i < 512; ++p1i)
+              if (pram_pages_to_free_on_exit[p3i][p2i][p1i])
+                paging::free_pram_page(
+                  paging::pte_to_paddr(p1s[p3i][p2i][p1i]));
+
+            //we free the p1 and the pram list
+            paging::free_pram_page(paging::pte_to_paddr(p2s[p3i][p2i]));
+            paging::unmap_kernel_page((uint64_t)p1s[p3i][p2i]);
+            delete[] pram_pages_to_free_on_exit[p3i][p2i];
+
+          }
+
+        //free the p2, the p1 list, and the pram list list
+        paging::free_pram_page(paging::pte_to_paddr(p3[p3i]));
+        paging::unmap_kernel_page((uint64_t)p2s[p3i]);
+        delete[] p1s[p3i];
+        delete[] pram_pages_to_free_on_exit[p3i];
+
+      }
+
+    //finally, we free the p3 and the p4
+    paging::free_pram_page(paging::pte_to_paddr(p4[0]));
+    paging::unmap_kernel_page((uint64_t)p3);
+    paging::free_pram_page(p4_paddr);
+    paging::unmap_kernel_page((uint64_t)p4);
+
+  }
+
+  void app_memory::map_page(uint64_t vaddr, uint64_t paddr,
+    bool write, bool execute, bool free_pram_on_exit) {
+
+    int p1i = (vaddr >> 12) & 511;
+    int p2i = (vaddr >> 21) & 511;
+    int p3i = (vaddr >> 30) & 511;
+
+    if (p2s[p3i] == 0) {
+      uint64_t new_p2_paddr;
+      paging::map_new_kernel_page(p2s[p3i], new_p2_paddr);
+      p1s[p3i] = new v_page_table[512];
+      pram_pages_to_free_on_exit[p3i] = new bool *[512];
+      for (int i = 0; i < 512; ++i) {
+        p2s[p3i][i] = 0;
+        p1s[p3i][i] = 0;
+        pram_pages_to_free_on_exit[p3i][i] = 0;
+      }
+      p3[p3i] = paging::encode_pte(new_p2_paddr, true, true, true);
+    }
+
+    if (p1s[p3i][p2i] == 0) {
+      uint64_t new_p1_paddr;
+      paging::map_new_kernel_page(p1s[p3i][p2i], new_p1_paddr);
+      pram_pages_to_free_on_exit[p3i][p2i] = new bool[512];
+      for (int i = 0; i < 512; ++i) {
+        p1s[p3i][p2i][i] = 0;
+        pram_pages_to_free_on_exit[p3i][p2i][i] = false;
+      }
+      p2s[p3i][p2i] = paging::encode_pte(new_p1_paddr, true, true, true);
+    }
+
+    p1s[p3i][p2i][p1i] = paging::encode_pte(paddr, true, write, execute);
+    pram_pages_to_free_on_exit[p3i][p2i][p1i] = free_pram_on_exit;
+
+  }
+
+  void app_memory::unmap_page(uint64_t vaddr) {
+    int p1i = (vaddr >> 12) & 511;
+    int p2i = (vaddr >> 21) & 511;
+    int p3i = (vaddr >> 30) & 511;
+    if (pram_pages_to_free_on_exit[p3i][p2i][p1i]) {
+      pram_pages_to_free_on_exit[p3i][p2i][p1i] = false;
+      paging::free_pram_page(paging::pte_to_paddr(p1s[p3i][p2i][p1i]));
+    }
+    p1s[p3i][p2i][p1i] = 0;
+  }
+
+  bool app_memory::valid_to_read(
+    uint64_t vaddr_start, uint64_t vaddr_end, bool and_write) const {
+    if (vaddr_start > vaddr_end || vaddr_end > 0x8000000000)
+      return false;
+    vaddr_start = (vaddr_start / 4096) * 4096;
+    vaddr_end = (((vaddr_end - 1) / 4096) + 1) * 4096;
+    for (uint64_t vaddr = vaddr_start; vaddr < vaddr_end; ++vaddr) {
+      int p1i = (vaddr >> 12) & 511;
+      int p2i = (vaddr >> 21) & 511;
+      int p3i = (vaddr >> 30) & 511;
+      if (!p1s[p3i] || !p1s[p3i][p2i] || !(and_write
+            ? (p1s[p3i][p2i][p1i] & 0x1) : p1s[p3i][p2i][p1i]))
+        return false;
+    }
+    return true;
+  }
+
+  uint64_t app_memory::get_free_vaddr_pages(uint64_t count) {
+    uint64_t vaddr = 0x1000;
+    uint64_t run = 0;
+    while (true) {
+      if (run == count)
+        return vaddr;
+      if (vaddr + (run + 1) * 4096 > 0x4000000000)
+        //TODO: handle out of virtual memory
+        panic(0x9af5e6);
+      if (valid_to_read(vaddr + run * 4096, vaddr + (run + 1) * 4096, false)) {
+        vaddr += (run + 1) * 4096;
+        run = 0;
+      }
+      else
+        ++run;
+    }
+  }
+
+  uint64_t app_memory::map_new_stack() {
+    for (uint64_t base_vaddr = 0x4000000000;
+         base_vaddr < 0x8000000000; base_vaddr += 0x1000000)
+      if (!valid_to_read(base_vaddr + 4096, base_vaddr + 8192, false)) {
+
+        for (uint64_t vaddr = base_vaddr + 4096;
+             vaddr < base_vaddr + 0x1000000; vaddr += 4096) {
+
+          uint8_t *kvaddr;
+          uint64_t paddr;
+          paging::map_new_kernel_page(kvaddr, paddr);
+          for (int i = 0; i < 4096; ++i)
+            kvaddr[i] = 0;
+          paging::unmap_kernel_page(kvaddr);
+          map_page(vaddr, paddr, true, false, true);
+
+        }
+        return base_vaddr + 0x1000000;
+
+      }
+    //TODO: handle out of stacks
+    panic(0x9af5e6);
+
+  }
+
+  void app_memory::unmap_stack(uint64_t top) {
+    for (uint64_t vaddr = top - 0xfff000; vaddr < top; vaddr += 4096)
+      unmap_page(vaddr);
+  }
+
+  uint64_t app_memory::count_mapped_vram_pages() const {
+    uint64_t count = 0;
+    for (int p3i = 0; p3i < 512; ++p3i)
+      if (p3[p3i])
+        for (int p2i = 0; p2i < 512; ++p2i)
+          if (p2s[p3i][p2i])
+            for (int p1i = 0; p1i < 512; ++p1i)
+              if (p1s[p3i][p2i][p1i])
+                ++count;
+    return count;
+  }
+
+}