fix RWX perms warnings in link step

kernel/linker.ld

@@ -1,18 +1,30 @@
 ENTRY(kmain)
 
+PHDRS {
+    text PT_LOAD FLAGS(5);    /* Read + Execute */
+    rodata PT_LOAD FLAGS(4);  /* Read only */
+    data PT_LOAD FLAGS(6);    /* Read + Write */
+}
+
 SECTIONS {
     . = 1M;
 
     .text : {
         *(.text*)
-    }
+    } :text
+
+    .rodata : {
+        *(.rodata*)
+    } :rodata
+
+    .data : {
+        *(.data*)
+    } :data
 
-    .rodata : { *(.rodata*) }
-    .data : { *(.data*) }
     .bss : {
         *(.bss*)
         *(COMMON)
-    }
+    } :data
 
     .stack (NOLOAD) : {
         . = ALIGN(4);