Add post service diagnostic hook

- osinit test: Validate all early phase invariants still hold after service

Author: alfreb

api/kernel/diag.hpp

@@ -8,6 +8,7 @@ namespace kernel::diag {
   void post_bss() noexcept;
   void post_machine_init() noexcept;
   void post_init_libc() noexcept;
+  void post_service() noexcept;
 
   void default_post_init_libc() noexcept;
 

src/kernel/kernel.cpp

@@ -18,6 +18,7 @@
 #include <os.hpp>
 #include <kernel.hpp>
 #include <kernel/cpuid.hpp>
+#include <kernel/diag.hpp>
 #include <kernel/rng.hpp>
 #include <service>
 #include <cstdio>
@@ -168,6 +169,7 @@ void kernel::post_start()
 
   // service program start
   Service::start();
+  kernel::diag::hook<kernel::diag::post_service>();
 }
 
 void os::add_stdout(os::print_func func)
@@ -227,3 +229,5 @@ void os::print_timestamps(const bool enabled)
 {
   kernel::state().timestamps = enabled;
 }
+
+void __attribute__((weak)) kernel::diag::post_service() noexcept {}

src/plugins/field_medic/fieldmedic.cpp

@@ -21,6 +21,7 @@
 //#include <atomic>
 static int diag_failures  = 0;
 static int diag_successes = 0;
+static bool fieldmedic_registered = false;
 
 #define DIAGNOSE(TEST, TEXT, ...) \
 try {  \
@@ -63,6 +64,7 @@ namespace medic{
   __attribute__ ((constructor))
   void register_medic() {
     os::register_plugin(medic::init, "Field medic");
+    fieldmedic_registered = true;
   }
 
 
@@ -93,3 +95,21 @@ extern "C" char get_single_tbss(){
 extern "C" int get_single_tdata(){
   return medic::diag::__tl_data[0];
 }
+
+
+using namespace medic::diag;
+
+void kernel::diag::post_service() noexcept {
+  MYINFO("Service finished. Diagnosing.");
+  DIAGNOSE(fieldmedic_registered && diag_successes > 0 && diag_failures == 0,
+             "Field medic plugin active");
+  DIAGNOSE(invariant_post_bss(), "Post .bss invariant still holds");
+  DIAGNOSE(invariant_post_machine_init(), "Post machine init invariant still holds");
+  DIAGNOSE(invariant_post_init_libc(), "Post init libc invariant still holds");
+
+  if (diag_failures == 0){
+    MYINFO("Diagnose complete. Healthy  ✅");
+  } else {
+    MYINFO("Diagnose complete: %i / %i checks failed", diag_failures, (diag_failures + diag_successes));
+  }
+}