From 5ff355c0cdf48796bc16335e1af7f34c41dcf576 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 28 Jan 2021 08:41:18 +0100
Subject: [PATCH] Kernel: Generate coredump backtraces from "threads for
 coredump" list

This broke with the change that gave each process a list of its own
threads. Since threads are removed slightly earlier from that list
during process teardown, we're not able to use it for generating
coredump backtraces. Fortunately we have the "threads for coredump"
list for just this purpose. :^)
---
 Kernel/CoreDump.cpp | 6 ++----
 Kernel/Process.cpp  | 2 +-
 Kernel/Process.h    | 7 ++++++-
 Kernel/Thread.h     | 1 +
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Kernel/CoreDump.cpp b/Kernel/CoreDump.cpp
index b03f27da820..2f3007e8637 100644
--- a/Kernel/CoreDump.cpp
+++ b/Kernel/CoreDump.cpp
@@ -240,7 +240,7 @@ ByteBuffer CoreDump::create_notes_threads_data() const
 {
     ByteBuffer threads_data;
 
-    m_process->for_each_thread([&](Thread& thread) {
+    for (auto& thread : m_process->threads_for_coredump({})) {
         ByteBuffer entry_buff;
 
         ELF::Core::ThreadInfo info {};
@@ -251,9 +251,7 @@ ByteBuffer CoreDump::create_notes_threads_data() const
         entry_buff.append((void*)&info, sizeof(info));
 
         threads_data += entry_buff;
-
-        return IterationDecision::Continue;
-    });
+    }
     return threads_data;
 }
 
diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 09c494f25b9..8e49cc4187c 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -677,7 +677,7 @@ void Process::die()
     m_tty = nullptr;
 
     for_each_thread([&](auto& thread) {
-        m_threads_for_coredump.append(&thread);
+        m_threads_for_coredump.append(thread);
         return IterationDecision::Continue;
     });
 
diff --git a/Kernel/Process.h b/Kernel/Process.h
index ae43f88aeae..612bd6317d3 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -206,6 +206,9 @@ public:
     template<typename Callback>
     IterationDecision for_each_thread(Callback) const;
 
+    template<typename Callback>
+    IterationDecision for_each_thread_in_coredump(Callback) const;
+
     void die();
     void finalize();
 
@@ -500,6 +503,8 @@ public:
     HashMap<String, String>& coredump_metadata() { return m_coredump_metadata; }
     const HashMap<String, String>& coredump_metadata() const { return m_coredump_metadata; }
 
+    const NonnullRefPtrVector<Thread>& threads_for_coredump(Badge<CoreDump>) const { return m_threads_for_coredump; }
+
     PerformanceEventBuffer* perf_events() { return m_perf_event_buffer; }
 
 private:
@@ -662,7 +667,7 @@ private:
 
     HashMap<String, String> m_coredump_metadata;
 
-    Vector<RefPtr<Thread>> m_threads_for_coredump;
+    NonnullRefPtrVector<Thread> m_threads_for_coredump;
 };
 
 extern InlineLinkedList<Process>* g_processes;
diff --git a/Kernel/Thread.h b/Kernel/Thread.h
index 1cd6e182baa..f3f1bf95616 100644
--- a/Kernel/Thread.h
+++ b/Kernel/Thread.h
@@ -785,6 +785,7 @@ public:
     u32 stack_ptr() const { return m_tss.esp; }
 
     RegisterState& get_register_dump_from_stack();
+    const RegisterState& get_register_dump_from_stack() const { return const_cast<Thread*>(this)->get_register_dump_from_stack(); }
 
     TSS32& tss() { return m_tss; }
     const TSS32& tss() const { return m_tss; }