1 files changed, 33 insertions, 8 deletions
diff --git a/src/kernel/paging.c b/src/kernel/paging.c
index 36fb8a7..a0f7c3d 100644
--- a/src/kernel/paging.c
+++ b/src/kernel/paging.c
@@ -77,27 +77,47 @@ void *new_task_pd() {
 void *pd_user_allocate(void *pd, uint32_t vma, uint32_t pages, bool writable) {
   void *pma = allocate_user_pages(pages);
   if (!pma)
-    panic("Could not allocate user pages.");
+    PANIC("Could not allocate user pages.");
   for (uint32_t i = 0; i < pages; ++i)
     pd_map(pd, (uint32_t)pma + (i << 12), vma + (i << 12), writable);
   return pma;
 }
 
-void *pd_user_allocate_anywhere_writable(void *pd, uint32_t pages) {
+__attribute__ ((pure))
+static void *find_user_vma_run(void *pd, uint32_t pages) {
   uint32_t run = 0;
   for (void *vma = (void *)KERNEL_END; vma; vma += 4096) {
     if (pd_is_mapped(pd, (uint32_t)vma))
       run = 0;
-    else if (++run == pages) {
-      vma -= (pages - 1) * 4096;
-      for (uint32_t i = 0; i < pages; ++i)
-        pd_map(pd, (uint32_t)allocate_user_pages(1), (uint32_t)vma + 4096 * i, true);
-      return vma;
-    }
+    else if (++run == pages)
+      return vma - (pages - 1) * 4096;
   }
   return 0;
 }
 
+void *pd_user_allocate_anywhere_writable(void *pd, uint32_t pages) {
+  void *vma = find_user_vma_run(pd, pages);
+  if (!vma)
+    return 0;
+  for (uint32_t i = 0; i < pages; ++i)
+    pd_map(pd, (uint32_t)allocate_user_pages(1), (uint32_t)vma + 4096 * i, true);
+  return vma;
+}
+
+void user_allocate_anywhere_readonly_together(void *pd, uint32_t pages, void **vma_out, void **pma_out) {
+  *vma_out = find_user_vma_run(pd, pages);
+  if (!*vma_out) {
+    *pma_out = 0;
+    return;
+  }
+  *pma_out = allocate_user_pages(pages);
+  if (!*pma_out) {
+    *vma_out = 0;
+    return;
+  }
+  pd_map(pd, (uint32_t)*pma_out, (uint32_t)*vma_out, false);
+}
+
 #define KPAGE_DIR     ((uint32_t *)0x00005000)
 #define KPAGE_TABLE_0 ((uint32_t *)0x00400000)
 
@@ -118,6 +138,11 @@ void init_paging() {
   : : : "eax");
 }
 
+__attribute__ ((pure))
+void *vma_to_pma(void *pd, const void *vma) {
+  return (void *)(((uint32_t *)(((uint32_t *)pd)[(uint32_t)vma >> 22] & PE_ADDR_MASK))[((uint32_t)vma >> 12) % 1024] & PE_ADDR_MASK) + (uint32_t)vma % 4096;
+}
+
 void switch_to_kernel_cr3() {
   asm volatile (
     "mov $0x00005000, %%eax\n"