arm_interface: Expand backtrace generation

Returns results as a vector of entries for further processing. Logs addresses, offsets, and mangled name.

2 files changed, 194 insertions, 7 deletions

diff --git a/src/core/arm/arm_interface.cpp b/src/core/arm/arm_interface.cpp
index 2223cbeed..2945fcff8 100644
--- a/src/core/arm/arm_interface.cpp
+++ b/src/core/arm/arm_interface.cpp
@@ -2,26 +2,202 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <map>
+#include <optional>
+#include "common/bit_field.h"
 #include "common/common_types.h"
 #include "common/logging/log.h"
 #include "core/arm/arm_interface.h"
+#include "core/core.h"
 #include "core/memory.h"
 
 namespace Core {
-void ARM_Interface::LogBacktrace() const {
-    VAddr fp = GetReg(29);
-    VAddr lr = GetReg(30);
-    const VAddr sp = GetReg(13);
-    const VAddr pc = GetPC();
 
-    LOG_ERROR(Core_ARM, "Backtrace, sp={:016X}, pc={:016X}", sp, pc);
+namespace {
+
+constexpr u64 ELF_DYNAMIC_TAG_NULL = 0;
+constexpr u64 ELF_DYNAMIC_TAG_STRTAB = 5;
+constexpr u64 ELF_DYNAMIC_TAG_SYMTAB = 6;
+constexpr u64 ELF_DYNAMIC_TAG_SYMENT = 11;
+
+enum class ELFSymbolType : u8 {
+    None = 0,
+    Object = 1,
+    Function = 2,
+    Section = 3,
+    File = 4,
+    Common = 5,
+    TLS = 6,
+};
+
+enum class ELFSymbolBinding : u8 {
+    Local = 0,
+    Global = 1,
+    Weak = 2,
+};
+
+enum class ELFSymbolVisibility : u8 {
+    Default = 0,
+    Internal = 1,
+    Hidden = 2,
+    Protected = 3,
+};
+
+struct ELFSymbol {
+    u32 name_index;
+    union {
+        u8 info;
+
+        BitField<0, 4, ELFSymbolType> type;
+        BitField<4, 4, ELFSymbolBinding> binding;
+    };
+    ELFSymbolVisibility visibility;
+    u16 sh_index;
+    u64 value;
+    u64 size;
+};
+static_assert(sizeof(ELFSymbol) == 0x18, "ELFSymbol has incorrect size.");
+
+using Symbols = std::vector<std::pair<ELFSymbol, std::string>>;
+
+Symbols GetSymbols(VAddr text_offset) {
+    const auto mod_offset = text_offset + Memory::Read32(text_offset + 4);
+
+    if (mod_offset < text_offset || (mod_offset & 0b11) != 0 ||
+        Memory::Read32(mod_offset) != Common::MakeMagic('M', 'O', 'D', '0')) {
+        return {};
+    }
+
+    const auto dynamic_offset = Memory::Read32(mod_offset + 0x4) + mod_offset;
+
+    VAddr string_table_offset{};
+    VAddr symbol_table_offset{};
+    u64 symbol_entry_size{};
+
+    VAddr dynamic_index = dynamic_offset;
+    while (true) {
+        const auto tag = Memory::Read64(dynamic_index);
+        const auto value = Memory::Read64(dynamic_index + 0x8);
+        dynamic_index += 0x10;
+
+        if (tag == ELF_DYNAMIC_TAG_NULL)
+            break;
+
+        if (tag == ELF_DYNAMIC_TAG_STRTAB)
+            string_table_offset = value;
+        else if (tag == ELF_DYNAMIC_TAG_SYMTAB)
+            symbol_table_offset = value;
+        else if (tag == ELF_DYNAMIC_TAG_SYMENT)
+            symbol_entry_size = value;
+    }
+
+    if (string_table_offset == 0 || symbol_table_offset == 0 || symbol_entry_size == 0) {
+        return {};
+    }
+
+    const auto string_table_address = text_offset + string_table_offset;
+    const auto symbol_table_address = text_offset + symbol_table_offset;
+
+    Symbols out;
+
+    VAddr symbol_index = symbol_table_address;
+    while (symbol_index < string_table_address) {
+        ELFSymbol symbol{};
+        Memory::ReadBlock(symbol_index, &symbol, sizeof(ELFSymbol));
+
+        VAddr string_offset = string_table_address + symbol.name_index;
+        std::string name;
+        for (u8 c = Memory::Read8(string_offset); c != 0; c = Memory::Read8(++string_offset)) {
+            name += static_cast<char>(c);
+        }
+
+        symbol_index += symbol_entry_size;
+        out.push_back({symbol, name});
+    }
+
+    return out;
+}
+
+std::optional<std::string> GetSymbolName(const Symbols& symbols, VAddr func_address) {
+    const auto iter =
+        std::find_if(symbols.begin(), symbols.end(), [func_address](const auto& pair) {
+            const auto& [symbol, name] = pair;
+            const auto end_address = symbol.value + symbol.size;
+            return func_address >= symbol.value && func_address < end_address;
+        });
+
+    if (iter == symbols.end())
+        return std::nullopt;
+    return iter->second;
+}
+
+} // Anonymous namespace
+
+constexpr u64 SEGMENT_BASE = 0x7100000000ull;
+
+std::vector<ARM_Interface::BacktraceEntry> ARM_Interface::GetBacktrace() const {
+    std::vector<BacktraceEntry> out;
+
+    auto fp = GetReg(29);
+    auto lr = GetReg(30);
+
     while (true) {
-        LOG_ERROR(Core_ARM, "{:016X}", lr);
+        out.push_back({"", 0, lr, 0});
         if (!fp) {
             break;
         }
         lr = Memory::Read64(fp + 8) - 4;
         fp = Memory::Read64(fp);
     }
+
+    const auto& modules{System::GetInstance().GetRegisteredNSOModules()};
+    std::map<std::string, Symbols> symbols;
+    for (const auto& module : modules) {
+        symbols.insert_or_assign(module.second, GetSymbols(module.first));
+    }
+
+    for (auto& entry : out) {
+        VAddr base = 0;
+        for (const auto& module : modules) {
+            if (entry.original_address >= module.first) {
+                entry.module = module.second;
+                base = module.first;
+                break;
+            }
+        }
+
+        entry.offset = entry.original_address - base;
+        entry.address = SEGMENT_BASE + entry.offset;
+
+        if (entry.module.empty())
+            entry.module = "unknown";
+
+        const auto symbol_set = symbols.find(entry.module);
+        if (symbol_set != symbols.end()) {
+            const auto symbol = GetSymbolName(symbol_set->second, entry.offset);
+            if (symbol.has_value()) {
+                // TODO(DarkLordZach): Add demangling of symbol names.
+                entry.name = *symbol;
+            }
+        }
+    }
+
+    return out;
 }
+
+void ARM_Interface::LogBacktrace() const {
+    const VAddr sp = GetReg(13);
+    const VAddr pc = GetPC();
+    LOG_ERROR(Core_ARM, "Backtrace, sp={:016X}, pc={:016X}", sp, pc);
+    LOG_ERROR(Core_ARM, "{:20}{:20}{:20}{:20}{}", "Module Name", "Address", "Original Address",
+              "Offset", "Symbol");
+    LOG_ERROR(Core_ARM, "{}", std::string(100, '-'));
+
+    const auto backtrace = GetBacktrace();
+    for (const auto& entry : backtrace) {
+        LOG_ERROR(Core_ARM, "{:20}{:016X}    {:016X}    {:016X}    {}", entry.module, entry.address,
+                  entry.original_address, entry.offset, entry.name);
+    }
+}
+
 } // namespace Core
diff --git a/src/core/arm/arm_interface.h b/src/core/arm/arm_interface.h
index 978b1518f..c6691a8e1 100644
--- a/src/core/arm/arm_interface.h
+++ b/src/core/arm/arm_interface.h
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <array>
+#include <vector>
 #include "common/common_types.h"
 
 namespace Common {
@@ -152,6 +153,16 @@ public:
     /// Prepare core for thread reschedule (if needed to correctly handle state)
     virtual void PrepareReschedule() = 0;
 
+    struct BacktraceEntry {
+        std::string module;
+        u64 address;
+        u64 original_address;
+        u64 offset;
+        std::string name;
+    };
+
+    std::vector<BacktraceEntry> GetBacktrace() const;
+
     /// fp (= r29) points to the last frame record.
     /// Note that this is the frame record for the *previous* frame, not the current one.
     /// Note we need to subtract 4 from our last read to get the proper address