From c9118b84b77bdbc2c66f7dd394244aa53019789e Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gbeutner@serenityos.org>
Date: Tue, 27 Jul 2021 17:01:29 +0200
Subject: [PATCH] LibCoreDump: Make symbolication work when .text isn't the
 first segment

This can happen with binaries built with Clang or with a custom linker
script.
---
 Userland/Libraries/LibCoreDump/Backtrace.cpp | 10 +++++++---
 Userland/Libraries/LibCoreDump/Reader.cpp    | 13 +++++++++++++
 Userland/Libraries/LibCoreDump/Reader.h      |  1 +
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibCoreDump/Backtrace.cpp b/Userland/Libraries/LibCoreDump/Backtrace.cpp
index 9ce5c64695..68f20e7467 100644
--- a/Userland/Libraries/LibCoreDump/Backtrace.cpp
+++ b/Userland/Libraries/LibCoreDump/Backtrace.cpp
@@ -79,14 +79,18 @@ Backtrace::~Backtrace()
 
 void Backtrace::add_entry(const Reader& coredump, FlatPtr ip)
 {
-    auto* region = coredump.region_containing((FlatPtr)ip);
-    if (!region) {
+    auto* ip_region = coredump.region_containing((FlatPtr)ip);
+    if (!ip_region) {
         m_entries.append({ ip, {}, {}, {} });
         return;
     }
-    auto object_name = region->object_name();
+    auto object_name = ip_region->object_name();
     if (object_name == "Loader.so")
         return;
+    // We need to find the first region for the object, just in case
+    // the PT_LOAD header for the .text segment isn't the first one
+    // in the object file.
+    auto region = coredump.first_region_for_object(object_name);
     auto* object_info = object_info_for_region(*region);
     if (!object_info)
         return;
diff --git a/Userland/Libraries/LibCoreDump/Reader.cpp b/Userland/Libraries/LibCoreDump/Reader.cpp
index da4a67b92d..2698a1e859 100644
--- a/Userland/Libraries/LibCoreDump/Reader.cpp
+++ b/Userland/Libraries/LibCoreDump/Reader.cpp
@@ -137,6 +137,19 @@ const JsonObject Reader::process_info() const
     // FIXME: Maybe just cache this on the Reader instance after first access.
 }
 
+ELF::Core::MemoryRegionInfo const* Reader::first_region_for_object(StringView object_name) const
+{
+    ELF::Core::MemoryRegionInfo const* ret = nullptr;
+    for_each_memory_region_info([&ret, &object_name](auto& region_info) {
+        if (region_info.object_name() == object_name) {
+            ret = &region_info;
+            return IterationDecision::Break;
+        }
+        return IterationDecision::Continue;
+    });
+    return ret;
+}
+
 const ELF::Core::MemoryRegionInfo* Reader::region_containing(FlatPtr address) const
 {
     const ELF::Core::MemoryRegionInfo* ret = nullptr;
diff --git a/Userland/Libraries/LibCoreDump/Reader.h b/Userland/Libraries/LibCoreDump/Reader.h
index 2e6116b7b9..fbfbde3537 100644
--- a/Userland/Libraries/LibCoreDump/Reader.h
+++ b/Userland/Libraries/LibCoreDump/Reader.h
@@ -32,6 +32,7 @@ public:
     const ELF::Image& image() const { return m_coredump_image; }
 
     Optional<FlatPtr> peek_memory(FlatPtr address) const;
+    ELF::Core::MemoryRegionInfo const* first_region_for_object(StringView object_name) const;
     const ELF::Core::MemoryRegionInfo* region_containing(FlatPtr address) const;
 
     struct LibraryData {