src: large pages fix FreeBSD fix region size

Makes the size aligned to huge page size by
calculating it from the aligned lower and upper
boundary of the executable address.

PR-URL: #28735
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rich Trott <rtrott@gmail.com>

Author: devnexen

src/large_pages/node_large_page.cc

@@ -199,12 +199,14 @@ static struct text_region FindNodeTextRegion() {
      (entry->kve_protection & KVME_PROT_EXEC));
 
     if (!strcmp(exename.c_str(), entry->kve_path) && excmapping) {
-      size_t size = entry->kve_end - entry->kve_start;
+      char* estart =
+        reinterpret_cast<char*>(hugepage_align_up(entry->kve_start));
+      char* eend =
+        reinterpret_cast<char*>(hugepage_align_down(entry->kve_end));
+      size_t size = eend - estart;
       nregion.found_text_region = true;
-      nregion.from =
-         reinterpret_cast<char*>(hugepage_align_up(entry->kve_start));
-      nregion.to =
-         reinterpret_cast<char*>(hugepage_align_down(entry->kve_end));
+      nregion.from = estart;
+      nregion.to = eend;
       nregion.total_hugepages = size / hps;
       break;
     }