Kernel: Add (expensive) but valuable userspace symbols to stacks.

This is expensive because we have to page in the entire executable for every
process up front for this to work. This is due to the page fault code not
being strong enough to run while another process is active.

Note that we already had userspace symbols in *crash* stacks. This patch
adds them generally, so they show up in /proc, Process Manager, etc.

There's room for improvement here, but the debugging benefits way overshadow
the performance penalty right now. :^)

1 files changed, 7 insertions, 1 deletions

diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index 71194807c1..e2370135e0 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -1,3 +1,4 @@
+#include <AK/ELF/ELFLoader.h>
 #include <AK/StringBuilder.h>
 #include <Kernel/FileSystem/FileDescription.h>
 #include <Kernel/Process.h>
@@ -570,7 +571,12 @@ String Thread::backtrace(ProcessInspectionHandle&) const
         if (!symbol.address)
             break;
         if (!symbol.ksym) {
-            builder.appendf("%p\n", symbol.address);
+#ifdef EXPENSIVE_USERSPACE_STACKS
+            if (!Scheduler::is_active() && process.elf_loader() && process.elf_loader()->has_symbols())
+                builder.appendf("%p  %s\n", symbol.address, process.elf_loader()->symbolicate(symbol.address).characters());
+            else
+#endif
+                builder.appendf("%p\n", symbol.address);
             continue;
         }
         unsigned offset = symbol.address - symbol.ksym->address;