Added virtual to physical address mapping code.\nNot yet compiled or …

…tested.

src/physmem.c

@@ -0,0 +1,24 @@
+static int pagemap_fd;
+
+uint64_t phys_page(uint64_t virt_page)
+{
+  if (pagemap_fd == 0) {
+    if ((pagemap_fd = fopen("/proc/%d/pagemap", O_RD)) <= 0) {
+      perror("open pagemap");
+      return 0;
+    }
+  }
+  uint64_t data;
+  int len;
+  len = pread(pagemap_fd, &data, sizeof(data), virt_page * sizeof(uint64_t));
+  if (len != sizeof(data)) {
+    perror("pread");
+    return 0;
+  }
+  if (data & (1<<63) == 0) {
+    fprintf(stderr, "page %x not present: %x", virt_page, data);
+    return 0;
+  }
+  return data & ((1 << 55) - 1);
+}
+

src/physmem.lua

@@ -0,0 +1,23 @@
+module(...,package.seeall)
+
+-- From virtual page to physical page
+local cache = {}
+local pagesize = 4096
+
+-- Return the 64-bit physical address of virt_addr.
+function map (virt_addr)
+   virt_addr = ffi.cast("int64_t", virt_addr)
+   local virtpage = tonumber(virt_addr / page_size)
+   local offset   = tonumber(virt_addr % page_size)
+   local physpage = cache[virtpage] or resolve(virtpage)
+   return ffi.cast("int64_t", physpage * pagesize + offset)
+end
+
+-- Return (and cache) the physical page number of virtpage.
+function resolve (virtpage)
+   local physpage = C.virt_to_phys(page)
+   if phys_page == 0 then error("Unable to resolve page " .. virt_page) end
+   cache[virtpage] = physpage
+   return phys_page
+end
+