custom linker script for user apps to guarantee that sections are page-aligned

make-build.sh

@@ -52,7 +52,7 @@ echo "  command = ld -r \$in -o \$out" >> build.ninja
 
 #eventually maybe a libc will be linked in
 echo "rule user_app_ld" >> build.ninja
-echo "  command = ld ${COMMON_LD_FLAGS} \$in -o \$out" >> build.ninja
+echo "  command = ld ${COMMON_LD_FLAGS} -T src/user-apps/link.ld \$in -o \$out" >> build.ninja
 
 #builds everything in a directory
 #  $1 - source directory
@@ -102,25 +102,27 @@ cp_apps=""
 app_deps=""
 
 for dir in src/user-apps/*; do
+  if [ -d $dir ]; then
+
+    if [ -e $dir/libraries.txt ]; then
+      lib_paths=$(cat $dir/libraries.txt | sed -e 's/^.*$/build\/user-libs\/\0\/lib\0.o/' | tr '\n' ' ')
+    else
+      lib_paths=""
+    fi
+
+    app_name=$(echo $dir | sed -e 's/^src\/user-apps\///')
+    build_all $dir user_cc user_app_ld $app_name.elf "$lib_paths"
+
+    build_elf=$(echo $dir | sed -e 's/^src/build/')/$app_name.elf
+    disk_dir=build/disk/calcite/apps/$app_name
+    disk_elf=$disk_dir/$app_name.elf
+
+    cp_apps=$(echo "$cp_apps" \
+      "mkdir -p $disk_dir &&" \
+      "cp $build_elf $disk_elf &&")
+    app_deps="$app_deps $build_elf"
 
-  if [ -e $dir/libraries.txt ]; then
-    lib_paths=$(cat $dir/libraries.txt | sed -e 's/^.*$/build\/user-libs\/\0\/lib\0.o/' | tr '\n' ' ')
-  else
-    lib_paths=""
   fi
-
-  app_name=$(echo $dir | sed -e 's/^src\/user-apps\///')
-  build_all $dir user_cc user_app_ld $app_name.elf "$lib_paths"
-
-  build_elf=$(echo $dir | sed -e 's/^src/build/')/$app_name.elf
-  disk_dir=build/disk/calcite/apps/$app_name
-  disk_elf=$disk_dir/$app_name.elf
-
-  cp_apps=$(echo "$cp_apps" \
-    "mkdir -p $disk_dir &&" \
-    "cp $build_elf $disk_elf &&")
-  app_deps="$app_deps $build_elf"
-
 done
 
 echo "rule disk" >> build.ninja

src/user-apps/link.ld

@@ -0,0 +1,39 @@
+OUTPUT_FORMAT(elf64-x86-64)
+OUTPUT_ARCH(i386:x86-64)
+
+ENTRY(_start)
+
+PHDRS {
+  rx PT_LOAD FLAGS(5);
+  ro PT_LOAD FLAGS(4);
+  rw PT_LOAD FLAGS(6);
+}
+
+SECTIONS {
+
+  . = 0x400000;
+
+  .text : {
+    *(.text .text.*)
+  } : rx
+
+  . = ALIGN(4096);
+
+  .rodata : {
+    *(.rodata .rodata.*)
+  } : ro
+
+  . = ALIGN(4096);
+
+  .data : {
+    *(.data .data.*)
+  } : rw
+
+  . = ALIGN(4096);
+
+  .bss : {
+    *(.bss .bss.*)
+    *(COMMON)
+  } : rw
+
+}