Kernel+LibELF: Stop doing ELF symbolication in the kernel

Now that the CrashDaemon symbolicates crashes in userspace, let's take
this one step further and stop trying to symbolicate userspace programs
in the kernel at all.

Kernel/KSyms.cpp

@@ -30,7 +30,6 @@
 #include <Kernel/KSyms.h>
 #include <Kernel/Process.h>
 #include <Kernel/Scheduler.h>
-#include <LibELF/Loader.h>
 
 namespace Kernel {
 
@@ -129,11 +128,6 @@ NEVER_INLINE static void dump_backtrace_impl(FlatPtr base_pointer, bool use_ksym
         return;
     }
 
-    OwnPtr<Process::ELFBundle> elf_bundle;
-    auto current_process = Process::current();
-    if (current_process)
-        elf_bundle = current_process->elf_bundle();
-
     struct RecognizedSymbol {
         FlatPtr address;
         const KernelSymbol* symbol { nullptr };
@@ -170,18 +164,14 @@ NEVER_INLINE static void dump_backtrace_impl(FlatPtr base_pointer, bool use_ksym
         if (!symbol.address)
             break;
         if (!symbol.symbol) {
-            if (elf_bundle && elf_bundle->elf_loader->has_symbols()) {
-                dbg() << String::format("%p", symbol.address) << "  " << elf_bundle->elf_loader->symbolicate(symbol.address);
-            } else {
-                dbg() << String::format("%p", symbol.address) << " (no ELF symbols for process)";
-            }
+            dbgln("{:p}", symbol.address);
             continue;
         }
         size_t offset = symbol.address - symbol.symbol->address;
         if (symbol.symbol->address == g_highest_kernel_symbol_address && offset > 4096)
-            dbg() << String::format("%p", symbol.address);
+            dbgln("{:p}", symbol.address);
         else
-            dbg() << String::format("%p", symbol.address) << "  " << demangle(symbol.symbol->name) << " +" << offset;
+            dbgln("{:p}  {} +{}", symbol.address, demangle(symbol.symbol->name), offset);
     }
 }
 

Kernel/Process.cpp

@@ -52,7 +52,6 @@
 #include <Kernel/VM/SharedInodeVMObject.h>
 #include <LibC/errno_numbers.h>
 #include <LibC/limits.h>
-#include <LibELF/Loader.h>
 
 //#define DEBUG_IO
 //#define DEBUG_POLL_SELECT
@@ -462,8 +461,6 @@ void Process::crash(int signal, u32 eip, bool out_of_memory)
         if (eip >= 0xc0000000 && g_kernel_symbols_available) {
             auto* symbol = symbolicate_kernel_address(eip);
             dbg() << "\033[31;1m" << String::format("%p", eip) << "  " << (symbol ? demangle(symbol->name) : "(k?)") << " +" << (symbol ? eip - symbol->address : 0) << "\033[0m\n";
-        } else if (auto elf_bundle = this->elf_bundle()) {
-            dbg() << "\033[31;1m" << String::format("%p", eip) << "  " << elf_bundle->elf_loader->symbolicate(eip) << "\033[0m\n";
         } else {
             dbg() << "\033[31;1m" << String::format("%p", eip) << "  (?)\033[0m\n";
         }
@@ -891,23 +888,6 @@ void Process::set_tty(TTY* tty)
     m_tty = tty;
 }
 
-OwnPtr<Process::ELFBundle> Process::elf_bundle() const
-{
-    if (!m_executable)
-        return nullptr;
-    auto bundle = make<ELFBundle>();
-    if (!m_executable->inode().shared_vmobject()) {
-        return nullptr;
-    }
-    ASSERT(m_executable->inode().shared_vmobject());
-    auto& vmobject = *m_executable->inode().shared_vmobject();
-    bundle->region = MM.allocate_kernel_region_with_vmobject(const_cast<SharedInodeVMObject&>(vmobject), vmobject.size(), "ELF bundle", Region::Access::Read);
-    if (!bundle->region)
-        return nullptr;
-    bundle->elf_loader = ELF::Loader::create(bundle->region->vaddr().as_ptr(), bundle->region->size());
-    return bundle;
-}
-
 void Process::start_tracing_from(ProcessID tracer)
 {
     m_tracer = ThreadTracer::create(tracer);

Kernel/Process.h

@@ -48,10 +48,6 @@
 #include <LibC/signal_numbers.h>
 #include <LibELF/AuxiliaryVector.h>
 
-namespace ELF {
-class Loader;
-}
-
 namespace Kernel {
 
 timeval kgettimeofday();
@@ -471,12 +467,6 @@ public:
         return m_big_lock;
     }
 
-    struct ELFBundle {
-        OwnPtr<Region> region;
-        RefPtr<ELF::Loader> elf_loader;
-    };
-    OwnPtr<ELFBundle> elf_bundle() const;
-
     int icon_id() const
     {
         return m_icon_id;

Kernel/Profiling.cpp

@@ -31,7 +31,6 @@
 #include <Kernel/KSyms.h>
 #include <Kernel/Process.h>
 #include <Kernel/Profiling.h>
-#include <LibELF/Loader.h>
 
 namespace Kernel {
 

Kernel/Thread.cpp

@@ -40,7 +40,6 @@
 #include <Kernel/VM/PageDirectory.h>
 #include <Kernel/VM/ProcessPagingScope.h>
 #include <LibC/signal_numbers.h>
-#include <LibELF/Loader.h>
 
 //#define SIGNAL_DEBUG
 //#define THREAD_DEBUG
@@ -1039,7 +1038,7 @@ struct RecognizedSymbol {
     const KernelSymbol* symbol { nullptr };
 };
 
-static bool symbolicate(const RecognizedSymbol& symbol, const Process& process, StringBuilder& builder, Process::ELFBundle* elf_bundle)
+static bool symbolicate(const RecognizedSymbol& symbol, const Process& process, StringBuilder& builder)
 {
     if (!symbol.address)
         return false;
@@ -1049,10 +1048,7 @@ static bool symbolicate(const RecognizedSymbol& symbol, const Process& process,
         if (!is_user_address(VirtualAddress(symbol.address))) {
             builder.append("0xdeadc0de\n");
         } else {
-            if (elf_bundle && elf_bundle->elf_loader->has_symbols())
-                builder.appendf("%p  %s\n", symbol.address, elf_bundle->elf_loader->symbolicate(symbol.address).characters());
-            else
-                builder.appendf("%p\n", symbol.address);
+            builder.appendff("{:p}\n", symbol.address);
         }
         return true;
     }
@@ -1070,11 +1066,6 @@ String Thread::backtrace_impl()
     Vector<RecognizedSymbol, 128> recognized_symbols;
 
     auto& process = const_cast<Process&>(this->process());
-    OwnPtr<Process::ELFBundle> elf_bundle;
-    if (!Processor::current().in_irq()) {
-        // If we're handling IRQs we can't really safely symbolicate
-        elf_bundle = process.elf_bundle();
-    }
     auto stack_trace = Processor::capture_stack_trace(*this);
     ASSERT(!g_scheduler_lock.own_lock());
     ProcessPagingScope paging_scope(process);
@@ -1088,7 +1079,7 @@ String Thread::backtrace_impl()
 
     StringBuilder builder;
     for (auto& symbol : recognized_symbols) {
-        if (!symbolicate(symbol, process, builder, elf_bundle.ptr()))
+        if (!symbolicate(symbol, process, builder))
             break;
     }
     return builder.to_string();

Libraries/LibELF/Loader.cpp

@@ -151,22 +151,6 @@ Optional<Image::Symbol> Loader::find_symbol(u32 address, u32* out_offset) const
         return {};
 
     SortedSymbol* sorted_symbols = nullptr;
-#    ifdef KERNEL
-    if (!m_sorted_symbols_region) {
-        m_sorted_symbols_region = MM.allocate_kernel_region(PAGE_ROUND_UP(m_symbol_count * sizeof(SortedSymbol)), "Sorted symbols", Kernel::Region::Access::Read | Kernel::Region::Access::Write);
-        sorted_symbols = (SortedSymbol*)m_sorted_symbols_region->vaddr().as_ptr();
-        size_t index = 0;
-        m_image.for_each_symbol([&](auto& symbol) {
-            sorted_symbols[index++] = { symbol.value(), symbol.name() };
-            return IterationDecision::Continue;
-        });
-        quick_sort(sorted_symbols, sorted_symbols + m_symbol_count, [](auto& a, auto& b) {
-            return a.address < b.address;
-        });
-    } else {
-        sorted_symbols = (SortedSymbol*)m_sorted_symbols_region->vaddr().as_ptr();
-    }
-#    else
     if (m_sorted_symbols.is_empty()) {
         m_sorted_symbols.ensure_capacity(m_symbol_count);
         m_image.for_each_symbol([this](auto& symbol) {
@@ -178,7 +162,6 @@ Optional<Image::Symbol> Loader::find_symbol(u32 address, u32* out_offset) const
         });
     }
     sorted_symbols = m_sorted_symbols.data();
-#    endif
 
     for (size_t i = 0; i < m_symbol_count; ++i) {
         if (sorted_symbols[i].address > address) {
@@ -192,7 +175,6 @@ Optional<Image::Symbol> Loader::find_symbol(u32 address, u32* out_offset) const
     }
     return {};
 }
-#endif
 
 String Loader::symbolicate(u32 address, u32* out_offset) const
 {
@@ -202,22 +184,7 @@ String Loader::symbolicate(u32 address, u32* out_offset) const
         return "??";
     }
     SortedSymbol* sorted_symbols = nullptr;
-#ifdef KERNEL
-    if (!m_sorted_symbols_region) {
-        m_sorted_symbols_region = MM.allocate_kernel_region(PAGE_ROUND_UP(m_symbol_count * sizeof(SortedSymbol)), "Sorted symbols", Kernel::Region::Access::Read | Kernel::Region::Access::Write);
-        sorted_symbols = (SortedSymbol*)m_sorted_symbols_region->vaddr().as_ptr();
-        size_t index = 0;
-        m_image.for_each_symbol([&](auto& symbol) {
-            sorted_symbols[index++] = { symbol.value(), symbol.name() };
-            return IterationDecision::Continue;
-        });
-        quick_sort(sorted_symbols, sorted_symbols + m_symbol_count, [](auto& a, auto& b) {
-            return a.address < b.address;
-        });
-    } else {
-        sorted_symbols = (SortedSymbol*)m_sorted_symbols_region->vaddr().as_ptr();
-    }
-#else
+
     if (m_sorted_symbols.is_empty()) {
         m_sorted_symbols.ensure_capacity(m_symbol_count);
         m_image.for_each_symbol([this](auto& symbol) {
@@ -229,7 +196,6 @@ String Loader::symbolicate(u32 address, u32* out_offset) const
         });
     }
     sorted_symbols = m_sorted_symbols.data();
-#endif
 
     for (size_t i = 0; i < m_symbol_count; ++i) {
         if (sorted_symbols[i].address > address) {
@@ -240,14 +206,10 @@ String Loader::symbolicate(u32 address, u32* out_offset) const
             }
             auto& symbol = sorted_symbols[i - 1];
 
-#ifdef KERNEL
-            auto demangled_name = demangle(symbol.name);
-#else
             auto& demangled_name = symbol.demangled_name;
             if (demangled_name.is_null()) {
                 demangled_name = demangle(symbol.name);
             }
-#endif
 
             if (out_offset) {
                 *out_offset = address - symbol.address;
@@ -261,4 +223,6 @@ String Loader::symbolicate(u32 address, u32* out_offset) const
     return "??";
 }
 
+#endif
+
 } // end namespace ELF

Libraries/LibELF/Loader.h

@@ -87,9 +87,8 @@ private:
         Optional<Image::Symbol> symbol;
 #endif
     };
-#ifdef KERNEL
-    mutable OwnPtr<Kernel::Region> m_sorted_symbols_region;
-#else
+
+#ifndef KERNEL
     mutable Vector<SortedSymbol> m_sorted_symbols;
 #endif
 };