DevTools: Move to Userland/DevTools/

10 files changed, 1515 insertions, 0 deletions

diff --git a/Userland/DevTools/Profiler/CMakeLists.txt b/Userland/DevTools/Profiler/CMakeLists.txt
new file mode 100644
index 0000000000..1cb7b95140
--- /dev/null
+++ b/Userland/DevTools/Profiler/CMakeLists.txt
@@ -0,0 +1,10 @@
+set(SOURCES
+    DisassemblyModel.cpp
+    main.cpp
+    Profile.cpp
+    ProfileModel.cpp
+    ProfileTimelineWidget.cpp
+)
+
+serenity_app(Profiler ICON app-profiler)
+target_link_libraries(Profiler LibGUI LibX86 LibCoreDump)
diff --git a/Userland/DevTools/Profiler/DisassemblyModel.cpp b/Userland/DevTools/Profiler/DisassemblyModel.cpp
new file mode 100644
index 0000000000..4195f103cd
--- /dev/null
+++ b/Userland/DevTools/Profiler/DisassemblyModel.cpp
@@ -0,0 +1,202 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "DisassemblyModel.h"
+#include "Profile.h"
+#include <AK/MappedFile.h>
+#include <LibELF/Image.h>
+#include <LibGUI/Painter.h>
+#include <LibX86/Disassembler.h>
+#include <LibX86/ELFSymbolProvider.h>
+#include <ctype.h>
+#include <stdio.h>
+
+static const Gfx::Bitmap& heat_gradient()
+{
+    static RefPtr<Gfx::Bitmap> bitmap;
+    if (!bitmap) {
+        bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGB32, { 101, 1 });
+        GUI::Painter painter(*bitmap);
+        painter.fill_rect_with_gradient(Orientation::Horizontal, bitmap->rect(), Color::from_rgb(0xffc080), Color::from_rgb(0xff3000));
+    }
+    return *bitmap;
+}
+
+static Color color_for_percent(int percent)
+{
+    ASSERT(percent >= 0 && percent <= 100);
+    return heat_gradient().get_pixel(percent, 0);
+}
+
+DisassemblyModel::DisassemblyModel(Profile& profile, ProfileNode& node)
+    : m_profile(profile)
+    , m_node(node)
+{
+    OwnPtr<ELF::Image> kernel_elf;
+    const ELF::Image* elf;
+    FlatPtr base_address = 0;
+    if (m_node.address() >= 0xc0000000) {
+        if (!m_kernel_file) {
+            auto file_or_error = MappedFile::map("/boot/Kernel");
+            if (file_or_error.is_error())
+                return;
+            m_kernel_file = file_or_error.release_value();
+        }
+        kernel_elf = make<ELF::Image>((const u8*)m_kernel_file->data(), m_kernel_file->size());
+        elf = kernel_elf.ptr();
+    } else {
+        auto library_data = profile.libraries().library_containing(node.address());
+        if (!library_data) {
+            dbgln("no library data");
+            return;
+        }
+        elf = &library_data->elf;
+        base_address = library_data->base;
+    }
+
+    ASSERT(elf != nullptr);
+
+    auto symbol = elf->find_symbol(node.address() - base_address);
+    if (!symbol.has_value()) {
+        dbgln("DisassemblyModel: symbol not found");
+        return;
+    }
+    ASSERT(symbol.has_value());
+
+    auto view = symbol.value().raw_data();
+
+    X86::ELFSymbolProvider symbol_provider(*elf);
+    X86::SimpleInstructionStream stream((const u8*)view.characters_without_null_termination(), view.length());
+    X86::Disassembler disassembler(stream);
+
+    size_t offset_into_symbol = 0;
+    for (;;) {
+        auto insn = disassembler.next();
+        if (!insn.has_value())
+            break;
+        FlatPtr address_in_profiled_program = symbol.value().value() + offset_into_symbol;
+
+        auto disassembly = insn.value().to_string(address_in_profiled_program, &symbol_provider);
+
+        StringView instruction_bytes = view.substring_view(offset_into_symbol, insn.value().length());
+        size_t samples_at_this_instruction = m_node.events_per_address().get(address_in_profiled_program).value_or(0);
+        float percent = ((float)samples_at_this_instruction / (float)m_node.event_count()) * 100.0f;
+
+        m_instructions.append({ insn.value(), disassembly, instruction_bytes, address_in_profiled_program, samples_at_this_instruction, percent });
+
+        offset_into_symbol += insn.value().length();
+    }
+}
+
+DisassemblyModel::~DisassemblyModel()
+{
+}
+
+int DisassemblyModel::row_count(const GUI::ModelIndex&) const
+{
+    return m_instructions.size();
+}
+
+String DisassemblyModel::column_name(int column) const
+{
+    switch (column) {
+    case Column::SampleCount:
+        return m_profile.show_percentages() ? "% Samples" : "# Samples";
+    case Column::Address:
+        return "Address";
+    case Column::InstructionBytes:
+        return "Insn Bytes";
+    case Column::Disassembly:
+        return "Disassembly";
+    default:
+        ASSERT_NOT_REACHED();
+        return {};
+    }
+}
+
+struct ColorPair {
+    Color background;
+    Color foreground;
+};
+
+static Optional<ColorPair> color_pair_for(const InstructionData& insn)
+{
+    if (insn.percent == 0)
+        return {};
+
+    Color background = color_for_percent(insn.percent);
+    Color foreground;
+    if (insn.percent > 50)
+        foreground = Color::White;
+    else
+        foreground = Color::Black;
+    return ColorPair { background, foreground };
+}
+
+GUI::Variant DisassemblyModel::data(const GUI::ModelIndex& index, GUI::ModelRole role) const
+{
+    auto& insn = m_instructions[index.row()];
+
+    if (role == GUI::ModelRole::BackgroundColor) {
+        auto colors = color_pair_for(insn);
+        if (!colors.has_value())
+            return {};
+        return colors.value().background;
+    }
+
+    if (role == GUI::ModelRole::ForegroundColor) {
+        auto colors = color_pair_for(insn);
+        if (!colors.has_value())
+            return {};
+        return colors.value().foreground;
+    }
+
+    if (role == GUI::ModelRole::Display) {
+        if (index.column() == Column::SampleCount) {
+            if (m_profile.show_percentages())
+                return ((float)insn.event_count / (float)m_node.event_count()) * 100.0f;
+            return insn.event_count;
+        }
+        if (index.column() == Column::Address)
+            return String::formatted("{:p}", insn.address);
+        if (index.column() == Column::InstructionBytes) {
+            StringBuilder builder;
+            for (auto ch : insn.bytes) {
+                builder.appendff("{:02x} ", (u8)ch);
+            }
+            return builder.to_string();
+        }
+        if (index.column() == Column::Disassembly)
+            return insn.disassembly;
+        return {};
+    }
+    return {};
+}
+
+void DisassemblyModel::update()
+{
+    did_update();
+}
diff --git a/Userland/DevTools/Profiler/DisassemblyModel.h b/Userland/DevTools/Profiler/DisassemblyModel.h
new file mode 100644
index 0000000000..0d0e643292
--- /dev/null
+++ b/Userland/DevTools/Profiler/DisassemblyModel.h
@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibGUI/Model.h>
+#include <LibX86/Instruction.h>
+
+class Profile;
+class ProfileNode;
+
+struct InstructionData {
+    X86::Instruction insn;
+    String disassembly;
+    StringView bytes;
+    FlatPtr address { 0 };
+    u32 event_count { 0 };
+    float percent { 0 };
+};
+
+class DisassemblyModel final : public GUI::Model {
+public:
+    static NonnullRefPtr<DisassemblyModel> create(Profile& profile, ProfileNode& node)
+    {
+        return adopt(*new DisassemblyModel(profile, node));
+    }
+
+    enum Column {
+        Address,
+        SampleCount,
+        InstructionBytes,
+        Disassembly,
+        __Count
+    };
+
+    virtual ~DisassemblyModel() override;
+
+    virtual int row_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override;
+    virtual int column_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return Column::__Count; }
+    virtual String column_name(int) const override;
+    virtual GUI::Variant data(const GUI::ModelIndex&, GUI::ModelRole) const override;
+    virtual void update() override;
+
+private:
+    DisassemblyModel(Profile&, ProfileNode&);
+
+    Profile& m_profile;
+    ProfileNode& m_node;
+    RefPtr<MappedFile> m_kernel_file;
+
+    Vector<InstructionData> m_instructions;
+};
diff --git a/Userland/DevTools/Profiler/Profile.cpp b/Userland/DevTools/Profiler/Profile.cpp
new file mode 100644
index 0000000000..8e8e986841
--- /dev/null
+++ b/Userland/DevTools/Profiler/Profile.cpp
@@ -0,0 +1,399 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Profile.h"
+#include "DisassemblyModel.h"
+#include "ProfileModel.h"
+#include <AK/HashTable.h>
+#include <AK/MappedFile.h>
+#include <AK/QuickSort.h>
+#include <AK/RefPtr.h>
+#include <LibCore/File.h>
+#include <LibELF/Image.h>
+#include <stdio.h>
+#include <sys/stat.h>
+
+static void sort_profile_nodes(Vector<NonnullRefPtr<ProfileNode>>& nodes)
+{
+    quick_sort(nodes.begin(), nodes.end(), [](auto& a, auto& b) {
+        return a->event_count() >= b->event_count();
+    });
+
+    for (auto& child : nodes)
+        child->sort_children();
+}
+
+Profile::Profile(String executable_path, Vector<Event> events, NonnullOwnPtr<LibraryMetadata> library_metadata)
+    : m_executable_path(move(executable_path))
+    , m_events(move(events))
+    , m_library_metadata(move(library_metadata))
+{
+    m_first_timestamp = m_events.first().timestamp;
+    m_last_timestamp = m_events.last().timestamp;
+
+    m_model = ProfileModel::create(*this);
+
+    for (auto& event : m_events) {
+        m_deepest_stack_depth = max((u32)event.frames.size(), m_deepest_stack_depth);
+    }
+
+    rebuild_tree();
+}
+
+Profile::~Profile()
+{
+}
+
+GUI::Model& Profile::model()
+{
+    return *m_model;
+}
+
+void Profile::rebuild_tree()
+{
+    u32 filtered_event_count = 0;
+    Vector<NonnullRefPtr<ProfileNode>> roots;
+
+    auto find_or_create_root = [&roots](const String& symbol, u32 address, u32 offset, u64 timestamp) -> ProfileNode& {
+        for (size_t i = 0; i < roots.size(); ++i) {
+            auto& root = roots[i];
+            if (root->symbol() == symbol) {
+                return root;
+            }
+        }
+        auto new_root = ProfileNode::create(symbol, address, offset, timestamp);
+        roots.append(new_root);
+        return new_root;
+    };
+
+    HashTable<FlatPtr> live_allocations;
+
+    for (auto& event : m_events) {
+        if (has_timestamp_filter_range()) {
+            auto timestamp = event.timestamp;
+            if (timestamp < m_timestamp_filter_range_start || timestamp > m_timestamp_filter_range_end)
+                continue;
+        }
+
+        if (event.type == "malloc")
+            live_allocations.set(event.ptr);
+        else if (event.type == "free")
+            live_allocations.remove(event.ptr);
+    }
+
+    for (size_t event_index = 0; event_index < m_events.size(); ++event_index) {
+        auto& event = m_events.at(event_index);
+        if (has_timestamp_filter_range()) {
+            auto timestamp = event.timestamp;
+            if (timestamp < m_timestamp_filter_range_start || timestamp > m_timestamp_filter_range_end)
+                continue;
+        }
+
+        if (event.type == "malloc" && !live_allocations.contains(event.ptr))
+            continue;
+
+        if (event.type == "free")
+            continue;
+
+        auto for_each_frame = [&]<typename Callback>(Callback callback) {
+            if (!m_inverted) {
+                for (size_t i = 0; i < event.frames.size(); ++i) {
+                    if (callback(event.frames.at(i), i == event.frames.size() - 1) == IterationDecision::Break)
+                        break;
+                }
+            } else {
+                for (ssize_t i = event.frames.size() - 1; i >= 0; --i) {
+                    if (callback(event.frames.at(i), static_cast<size_t>(i) == event.frames.size() - 1) == IterationDecision::Break)
+                        break;
+                }
+            }
+        };
+
+        if (!m_show_top_functions) {
+            ProfileNode* node = nullptr;
+            for_each_frame([&](const Frame& frame, bool is_innermost_frame) {
+                auto& symbol = frame.symbol;
+                auto& address = frame.address;
+                auto& offset = frame.offset;
+
+                if (symbol.is_empty())
+                    return IterationDecision::Break;
+
+                if (!node)
+                    node = &find_or_create_root(symbol, address, offset, event.timestamp);
+                else
+                    node = &node->find_or_create_child(symbol, address, offset, event.timestamp);
+
+                node->increment_event_count();
+                if (is_innermost_frame) {
+                    node->add_event_address(address);
+                    node->increment_self_count();
+                }
+                return IterationDecision::Continue;
+            });
+        } else {
+            for (size_t i = 0; i < event.frames.size(); ++i) {
+                ProfileNode* node = nullptr;
+                ProfileNode* root = nullptr;
+                for (size_t j = i; j < event.frames.size(); ++j) {
+                    auto& frame = event.frames.at(j);
+                    auto& symbol = frame.symbol;
+                    auto& address = frame.address;
+                    auto& offset = frame.offset;
+                    if (symbol.is_empty())
+                        break;
+
+                    if (!node) {
+                        node = &find_or_create_root(symbol, address, offset, event.timestamp);
+                        root = node;
+                        root->will_track_seen_events(m_events.size());
+                    } else {
+                        node = &node->find_or_create_child(symbol, address, offset, event.timestamp);
+                    }
+
+                    if (!root->has_seen_event(event_index)) {
+                        root->did_see_event(event_index);
+                        root->increment_event_count();
+                    } else if (node != root) {
+                        node->increment_event_count();
+                    }
+
+                    if (j == event.frames.size() - 1) {
+                        node->add_event_address(address);
+                        node->increment_self_count();
+                    }
+                }
+            }
+        }
+
+        ++filtered_event_count;
+    }
+
+    sort_profile_nodes(roots);
+
+    m_filtered_event_count = filtered_event_count;
+    m_roots = move(roots);
+    m_model->update();
+}
+
+Result<NonnullOwnPtr<Profile>, String> Profile::load_from_perfcore_file(const StringView& path)
+{
+    auto file = Core::File::construct(path);
+    if (!file->open(Core::IODevice::ReadOnly))
+        return String::formatted("Unable to open {}, error: {}", path, file->error_string());
+
+    auto json = JsonValue::from_string(file->read_all());
+    if (!json.has_value() || !json.value().is_object())
+        return String { "Invalid perfcore format (not a JSON object)" };
+
+    auto& object = json.value().as_object();
+    auto executable_path = object.get("executable").to_string();
+
+    auto pid = object.get("pid");
+    if (!pid.is_u32())
+        return String { "Invalid perfcore format (no process ID)" };
+
+    auto file_or_error = MappedFile::map("/boot/Kernel");
+    OwnPtr<ELF::Image> kernel_elf;
+    if (!file_or_error.is_error())
+        kernel_elf = make<ELF::Image>(file_or_error.value()->bytes());
+
+    auto events_value = object.get("events");
+    if (!events_value.is_array())
+        return String { "Malformed profile (events is not an array)" };
+
+    auto regions_value = object.get("regions");
+    if (!regions_value.is_array() || regions_value.as_array().is_empty())
+        return String { "Malformed profile (regions is not an array, or it is empty)" };
+
+    auto& perf_events = events_value.as_array();
+    if (perf_events.is_empty())
+        return String { "No events captured (targeted process was never on CPU)" };
+
+    auto library_metadata = make<LibraryMetadata>(regions_value.as_array());
+
+    Vector<Event> events;
+
+    for (auto& perf_event_value : perf_events.values()) {
+        auto& perf_event = perf_event_value.as_object();
+
+        Event event;
+
+        event.timestamp = perf_event.get("timestamp").to_number<u64>();
+        event.type = perf_event.get("type").to_string();
+
+        if (event.type == "malloc") {
+            event.ptr = perf_event.get("ptr").to_number<FlatPtr>();
+            event.size = perf_event.get("size").to_number<size_t>();
+        } else if (event.type == "free") {
+            event.ptr = perf_event.get("ptr").to_number<FlatPtr>();
+        }
+
+        auto stack_array = perf_event.get("stack").as_array();
+        for (ssize_t i = stack_array.values().size() - 1; i >= 0; --i) {
+            auto& frame = stack_array.at(i);
+            auto ptr = frame.to_number<u32>();
+            u32 offset = 0;
+            String symbol;
+
+            if (ptr >= 0xc0000000) {
+                if (kernel_elf) {
+                    symbol = kernel_elf->symbolicate(ptr, &offset);
+                } else {
+                    symbol = "??";
+                }
+            } else {
+                symbol = library_metadata->symbolicate(ptr, offset);
+            }
+
+            event.frames.append({ symbol, ptr, offset });
+        }
+
+        if (event.frames.size() < 2)
+            continue;
+
+        FlatPtr innermost_frame_address = event.frames.at(1).address;
+        event.in_kernel = innermost_frame_address >= 0xc0000000;
+
+        events.append(move(event));
+    }
+
+    return adopt_own(*new Profile(executable_path, move(events), move(library_metadata)));
+}
+
+void ProfileNode::sort_children()
+{
+    sort_profile_nodes(m_children);
+}
+
+void Profile::set_timestamp_filter_range(u64 start, u64 end)
+{
+    if (m_has_timestamp_filter_range && m_timestamp_filter_range_start == start && m_timestamp_filter_range_end == end)
+        return;
+    m_has_timestamp_filter_range = true;
+
+    m_timestamp_filter_range_start = min(start, end);
+    m_timestamp_filter_range_end = max(start, end);
+
+    rebuild_tree();
+}
+
+void Profile::clear_timestamp_filter_range()
+{
+    if (!m_has_timestamp_filter_range)
+        return;
+    m_has_timestamp_filter_range = false;
+    rebuild_tree();
+}
+
+void Profile::set_inverted(bool inverted)
+{
+    if (m_inverted == inverted)
+        return;
+    m_inverted = inverted;
+    rebuild_tree();
+}
+
+void Profile::set_show_top_functions(bool show)
+{
+    if (m_show_top_functions == show)
+        return;
+    m_show_top_functions = show;
+    rebuild_tree();
+}
+
+void Profile::set_show_percentages(bool show_percentages)
+{
+    if (m_show_percentages == show_percentages)
+        return;
+    m_show_percentages = show_percentages;
+}
+
+void Profile::set_disassembly_index(const GUI::ModelIndex& index)
+{
+    if (m_disassembly_index == index)
+        return;
+    m_disassembly_index = index;
+    auto* node = static_cast<ProfileNode*>(index.internal_data());
+    m_disassembly_model = DisassemblyModel::create(*this, *node);
+}
+
+GUI::Model* Profile::disassembly_model()
+{
+    return m_disassembly_model;
+}
+
+Profile::LibraryMetadata::LibraryMetadata(JsonArray regions)
+    : m_regions(move(regions))
+{
+    for (auto& region_value : m_regions.values()) {
+        auto& region = region_value.as_object();
+        auto base = region.get("base").as_u32();
+        auto size = region.get("size").as_u32();
+        auto name = region.get("name").as_string();
+
+        String path;
+        if (name.contains("Loader.so"))
+            path = "Loader.so";
+        else if (!name.contains(":"))
+            continue;
+        else
+            path = name.substring(0, name.view().find_first_of(":").value());
+
+        if (name.contains(".so"))
+            path = String::formatted("/usr/lib/{}", path);
+
+        auto file_or_error = MappedFile::map(path);
+        if (file_or_error.is_error()) {
+            m_libraries.set(name, {});
+            continue;
+        }
+        auto elf = ELF::Image(file_or_error.value()->bytes());
+        if (!elf.is_valid())
+            continue;
+        auto library = make<Library>(base, size, name, file_or_error.release_value(), move(elf));
+        m_libraries.set(name, move(library));
+    }
+}
+
+const Profile::LibraryMetadata::Library* Profile::LibraryMetadata::library_containing(FlatPtr ptr) const
+{
+    for (auto& it : m_libraries) {
+        if (!it.value)
+            continue;
+        auto& library = *it.value;
+        if (ptr >= library.base && ptr < (library.base + library.size))
+            return &library;
+    }
+    return nullptr;
+}
+
+String Profile::LibraryMetadata::symbolicate(FlatPtr ptr, u32& offset) const
+{
+    if (auto* library = library_containing(ptr))
+        return String::formatted("[{}] {}", library->name, library->elf.symbolicate(ptr - library->base, &offset));
+    return "??";
+}
diff --git a/Userland/DevTools/Profiler/Profile.h b/Userland/DevTools/Profiler/Profile.h
new file mode 100644
index 0000000000..0acf3e917f
--- /dev/null
+++ b/Userland/DevTools/Profiler/Profile.h
@@ -0,0 +1,234 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Bitmap.h>
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
+#include <AK/JsonValue.h>
+#include <AK/MappedFile.h>
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/OwnPtr.h>
+#include <AK/Result.h>
+#include <LibELF/Image.h>
+#include <LibGUI/Forward.h>
+#include <LibGUI/ModelIndex.h>
+
+class ProfileModel;
+class DisassemblyModel;
+
+class ProfileNode : public RefCounted<ProfileNode> {
+public:
+    static NonnullRefPtr<ProfileNode> create(const String& symbol, u32 address, u32 offset, u64 timestamp)
+    {
+        return adopt(*new ProfileNode(symbol, address, offset, timestamp));
+    }
+
+    // These functions are only relevant for root nodes
+    void will_track_seen_events(size_t profile_event_count)
+    {
+        if (m_seen_events.size() != profile_event_count)
+            m_seen_events = Bitmap::create(profile_event_count, false);
+    }
+    bool has_seen_event(size_t event_index) const { return m_seen_events.get(event_index); }
+    void did_see_event(size_t event_index) { m_seen_events.set(event_index, true); }
+
+    const String& symbol() const { return m_symbol; }
+    u32 address() const { return m_address; }
+    u32 offset() const { return m_offset; }
+    u64 timestamp() const { return m_timestamp; }
+
+    u32 event_count() const { return m_event_count; }
+    u32 self_count() const { return m_self_count; }
+
+    int child_count() const { return m_children.size(); }
+    const Vector<NonnullRefPtr<ProfileNode>>& children() const { return m_children; }
+
+    void add_child(ProfileNode& child)
+    {
+        if (child.m_parent == this)
+            return;
+        ASSERT(!child.m_parent);
+        child.m_parent = this;
+        m_children.append(child);
+    }
+
+    ProfileNode& find_or_create_child(const String& symbol, u32 address, u32 offset, u64 timestamp)
+    {
+        for (size_t i = 0; i < m_children.size(); ++i) {
+            auto& child = m_children[i];
+            if (child->symbol() == symbol) {
+                return child;
+            }
+        }
+        auto new_child = ProfileNode::create(symbol, address, offset, timestamp);
+        add_child(new_child);
+        return new_child;
+    };
+
+    ProfileNode* parent() { return m_parent; }
+    const ProfileNode* parent() const { return m_parent; }
+
+    void increment_event_count() { ++m_event_count; }
+    void increment_self_count() { ++m_self_count; }
+
+    void sort_children();
+
+    const HashMap<FlatPtr, size_t>& events_per_address() const { return m_events_per_address; }
+    void add_event_address(FlatPtr address)
+    {
+        auto it = m_events_per_address.find(address);
+        if (it == m_events_per_address.end())
+            m_events_per_address.set(address, 1);
+        else
+            m_events_per_address.set(address, it->value + 1);
+    }
+
+private:
+    explicit ProfileNode(const String& symbol, u32 address, u32 offset, u64 timestamp)
+        : m_symbol(symbol)
+        , m_address(address)
+        , m_offset(offset)
+        , m_timestamp(timestamp)
+    {
+    }
+
+    ProfileNode* m_parent { nullptr };
+    String m_symbol;
+    u32 m_address { 0 };
+    u32 m_offset { 0 };
+    u32 m_event_count { 0 };
+    u32 m_self_count { 0 };
+    u64 m_timestamp { 0 };
+    Vector<NonnullRefPtr<ProfileNode>> m_children;
+    HashMap<FlatPtr, size_t> m_events_per_address;
+    Bitmap m_seen_events;
+};
+
+class Profile {
+public:
+    static Result<NonnullOwnPtr<Profile>, String> load_from_perfcore_file(const StringView& path);
+    ~Profile();
+
+    GUI::Model& model();
+    GUI::Model* disassembly_model();
+
+    void set_disassembly_index(const GUI::ModelIndex&);
+
+    const Vector<NonnullRefPtr<ProfileNode>>& roots() const { return m_roots; }
+
+    struct Frame {
+        String symbol;
+        u32 address { 0 };
+        u32 offset { 0 };
+    };
+
+    struct Event {
+        u64 timestamp { 0 };
+        String type;
+        FlatPtr ptr { 0 };
+        size_t size { 0 };
+        bool in_kernel { false };
+        Vector<Frame> frames;
+    };
+
+    u32 filtered_event_count() const { return m_filtered_event_count; }
+
+    const Vector<Event>& events() const { return m_events; }
+
+    u64 length_in_ms() const { return m_last_timestamp - m_first_timestamp; }
+    u64 first_timestamp() const { return m_first_timestamp; }
+    u64 last_timestamp() const { return m_last_timestamp; }
+    u32 deepest_stack_depth() const { return m_deepest_stack_depth; }
+
+    void set_timestamp_filter_range(u64 start, u64 end);
+    void clear_timestamp_filter_range();
+    bool has_timestamp_filter_range() const { return m_has_timestamp_filter_range; }
+
+    bool is_inverted() const { return m_inverted; }
+    void set_inverted(bool);
+
+    void set_show_top_functions(bool);
+
+    bool show_percentages() const { return m_show_percentages; }
+    void set_show_percentages(bool);
+
+    const String& executable_path() const { return m_executable_path; }
+
+    class LibraryMetadata {
+    public:
+        LibraryMetadata(JsonArray regions);
+
+        String symbolicate(FlatPtr ptr, u32& offset) const;
+
+        struct Library {
+            FlatPtr base;
+            size_t size;
+            String name;
+            NonnullRefPtr<MappedFile> file;
+            ELF::Image elf;
+        };
+
+        const Library* library_containing(FlatPtr) const;
+
+    private:
+        mutable HashMap<String, OwnPtr<Library>> m_libraries;
+        JsonArray m_regions;
+    };
+
+    const LibraryMetadata& libraries() const { return *m_library_metadata; }
+
+private:
+    Profile(String executable_path, Vector<Event>, NonnullOwnPtr<LibraryMetadata>);
+
+    void rebuild_tree();
+
+    String m_executable_path;
+
+    RefPtr<ProfileModel> m_model;
+    RefPtr<DisassemblyModel> m_disassembly_model;
+
+    GUI::ModelIndex m_disassembly_index;
+
+    Vector<NonnullRefPtr<ProfileNode>> m_roots;
+    u32 m_filtered_event_count { 0 };
+    u64 m_first_timestamp { 0 };
+    u64 m_last_timestamp { 0 };
+
+    Vector<Event> m_events;
+
+    NonnullOwnPtr<LibraryMetadata> m_library_metadata;
+
+    bool m_has_timestamp_filter_range { false };
+    u64 m_timestamp_filter_range_start { 0 };
+    u64 m_timestamp_filter_range_end { 0 };
+
+    u32 m_deepest_stack_depth { 0 };
+    bool m_inverted { false };
+    bool m_show_top_functions { false };
+    bool m_show_percentages { false };
+};
diff --git a/Userland/DevTools/Profiler/ProfileModel.cpp b/Userland/DevTools/Profiler/ProfileModel.cpp
new file mode 100644
index 0000000000..caf1819446
--- /dev/null
+++ b/Userland/DevTools/Profiler/ProfileModel.cpp
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "ProfileModel.h"
+#include "Profile.h"
+#include <AK/StringBuilder.h>
+#include <ctype.h>
+#include <stdio.h>
+
+ProfileModel::ProfileModel(Profile& profile)
+    : m_profile(profile)
+{
+    m_user_frame_icon.set_bitmap_for_size(16, Gfx::Bitmap::load_from_file("/res/icons/16x16/inspector-object.png"));
+    m_kernel_frame_icon.set_bitmap_for_size(16, Gfx::Bitmap::load_from_file("/res/icons/16x16/inspector-object-red.png"));
+}
+
+ProfileModel::~ProfileModel()
+{
+}
+
+GUI::ModelIndex ProfileModel::index(int row, int column, const GUI::ModelIndex& parent) const
+{
+    if (!parent.is_valid()) {
+        if (m_profile.roots().is_empty())
+            return {};
+        return create_index(row, column, m_profile.roots().at(row).ptr());
+    }
+    auto& remote_parent = *static_cast<ProfileNode*>(parent.internal_data());
+    return create_index(row, column, remote_parent.children().at(row).ptr());
+}
+
+GUI::ModelIndex ProfileModel::parent_index(const GUI::ModelIndex& index) const
+{
+    if (!index.is_valid())
+        return {};
+    auto& node = *static_cast<ProfileNode*>(index.internal_data());
+    if (!node.parent())
+        return {};
+
+    // NOTE: If the parent has no parent, it's a root, so we have to look among the roots.
+    if (!node.parent()->parent()) {
+        for (size_t row = 0; row < m_profile.roots().size(); ++row) {
+            if (m_profile.roots()[row].ptr() == node.parent()) {
+                return create_index(row, index.column(), node.parent());
+            }
+        }
+        ASSERT_NOT_REACHED();
+        return {};
+    }
+
+    for (size_t row = 0; row < node.parent()->parent()->children().size(); ++row) {
+        if (node.parent()->parent()->children()[row].ptr() == node.parent())
+            return create_index(row, index.column(), node.parent());
+    }
+
+    ASSERT_NOT_REACHED();
+    return {};
+}
+
+int ProfileModel::row_count(const GUI::ModelIndex& index) const
+{
+    if (!index.is_valid())
+        return m_profile.roots().size();
+    auto& node = *static_cast<ProfileNode*>(index.internal_data());
+    return node.children().size();
+}
+
+int ProfileModel::column_count(const GUI::ModelIndex&) const
+{
+    return Column::__Count;
+}
+
+String ProfileModel::column_name(int column) const
+{
+    switch (column) {
+    case Column::SampleCount:
+        return m_profile.show_percentages() ? "% Samples" : "# Samples";
+    case Column::SelfCount:
+        return m_profile.show_percentages() ? "% Self" : "# Self";
+    case Column::StackFrame:
+        return "Stack Frame";
+    default:
+        ASSERT_NOT_REACHED();
+        return {};
+    }
+}
+
+GUI::Variant ProfileModel::data(const GUI::ModelIndex& index, GUI::ModelRole role) const
+{
+    auto* node = static_cast<ProfileNode*>(index.internal_data());
+    if (role == GUI::ModelRole::TextAlignment) {
+        if (index.column() == Column::SampleCount || index.column() == Column::SelfCount)
+            return Gfx::TextAlignment::CenterRight;
+    }
+    if (role == GUI::ModelRole::Icon) {
+        if (index.column() == Column::StackFrame) {
+            if (node->address() >= 0xc0000000)
+                return m_kernel_frame_icon;
+            return m_user_frame_icon;
+        }
+        return {};
+    }
+    if (role == GUI::ModelRole::Display) {
+        if (index.column() == Column::SampleCount) {
+            if (m_profile.show_percentages())
+                return ((float)node->event_count() / (float)m_profile.filtered_event_count()) * 100.0f;
+            return node->event_count();
+        }
+        if (index.column() == Column::SelfCount) {
+            if (m_profile.show_percentages())
+                return ((float)node->self_count() / (float)m_profile.filtered_event_count()) * 100.0f;
+            return node->self_count();
+        }
+        if (index.column() == Column::StackFrame)
+            return node->symbol();
+        return {};
+    }
+    return {};
+}
+
+void ProfileModel::update()
+{
+    did_update(Model::InvalidateAllIndexes);
+}
diff --git a/Userland/DevTools/Profiler/ProfileModel.h b/Userland/DevTools/Profiler/ProfileModel.h
new file mode 100644
index 0000000000..9b61dd5137
--- /dev/null
+++ b/Userland/DevTools/Profiler/ProfileModel.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibGUI/Model.h>
+
+class Profile;
+
+class ProfileModel final : public GUI::Model {
+public:
+    static NonnullRefPtr<ProfileModel> create(Profile& profile)
+    {
+        return adopt(*new ProfileModel(profile));
+    }
+
+    enum Column {
+        SampleCount,
+        SelfCount,
+        StackFrame,
+        __Count
+    };
+
+    virtual ~ProfileModel() override;
+
+    virtual int row_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override;
+    virtual int column_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override;
+    virtual String column_name(int) const override;
+    virtual GUI::Variant data(const GUI::ModelIndex&, GUI::ModelRole) const override;
+    virtual GUI::ModelIndex index(int row, int column, const GUI::ModelIndex& parent = GUI::ModelIndex()) const override;
+    virtual GUI::ModelIndex parent_index(const GUI::ModelIndex&) const override;
+    virtual void update() override;
+    virtual int tree_column() const override { return Column::StackFrame; }
+
+private:
+    explicit ProfileModel(Profile&);
+
+    Profile& m_profile;
+
+    GUI::Icon m_user_frame_icon;
+    GUI::Icon m_kernel_frame_icon;
+};
diff --git a/Userland/DevTools/Profiler/ProfileTimelineWidget.cpp b/Userland/DevTools/Profiler/ProfileTimelineWidget.cpp
new file mode 100644
index 0000000000..7d4552d300
--- /dev/null
+++ b/Userland/DevTools/Profiler/ProfileTimelineWidget.cpp
@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "ProfileTimelineWidget.h"
+#include "Profile.h"
+#include <LibGUI/Painter.h>
+
+ProfileTimelineWidget::ProfileTimelineWidget(Profile& profile)
+    : m_profile(profile)
+{
+    set_fill_with_background_color(true);
+    set_fixed_height(80);
+}
+
+ProfileTimelineWidget::~ProfileTimelineWidget()
+{
+}
+
+void ProfileTimelineWidget::paint_event(GUI::PaintEvent& event)
+{
+    GUI::Frame::paint_event(event);
+
+    GUI::Painter painter(*this);
+    painter.add_clip_rect(event.rect());
+
+    float column_width = (float)frame_inner_rect().width() / (float)m_profile.length_in_ms();
+    float frame_height = (float)frame_inner_rect().height() / (float)m_profile.deepest_stack_depth();
+
+    for (auto& event : m_profile.events()) {
+        u64 t = event.timestamp - m_profile.first_timestamp();
+        int x = (int)((float)t * column_width);
+        int cw = max(1, (int)column_width);
+
+        int column_height = frame_inner_rect().height() - (int)((float)event.frames.size() * frame_height);
+
+        bool in_kernel = event.in_kernel;
+        Color color = in_kernel ? Color::from_rgb(0xc25e5a) : Color::from_rgb(0x5a65c2);
+        for (int i = 0; i < cw; ++i)
+            painter.draw_line({ x + i, frame_thickness() + column_height }, { x + i, height() - frame_thickness() * 2 }, color);
+    }
+
+    u64 normalized_start_time = min(m_select_start_time, m_select_end_time);
+    u64 normalized_end_time = max(m_select_start_time, m_select_end_time);
+
+    int select_start_x = (int)((float)(normalized_start_time - m_profile.first_timestamp()) * column_width);
+    int select_end_x = (int)((float)(normalized_end_time - m_profile.first_timestamp()) * column_width);
+    painter.fill_rect({ select_start_x, frame_thickness(), select_end_x - select_start_x, height() - frame_thickness() * 2 }, Color(0, 0, 0, 60));
+}
+
+u64 ProfileTimelineWidget::timestamp_at_x(int x) const
+{
+    float column_width = (float)frame_inner_rect().width() / (float)m_profile.length_in_ms();
+    float ms_into_profile = (float)x / column_width;
+    return m_profile.first_timestamp() + (u64)ms_into_profile;
+}
+
+void ProfileTimelineWidget::mousedown_event(GUI::MouseEvent& event)
+{
+    if (event.button() != GUI::MouseButton::Left)
+        return;
+
+    m_selecting = true;
+    m_select_start_time = timestamp_at_x(event.x());
+    m_select_end_time = m_select_start_time;
+    m_profile.set_timestamp_filter_range(m_select_start_time, m_select_end_time);
+    update();
+}
+
+void ProfileTimelineWidget::mousemove_event(GUI::MouseEvent& event)
+{
+    if (!m_selecting)
+        return;
+
+    m_select_end_time = timestamp_at_x(event.x());
+    m_profile.set_timestamp_filter_range(m_select_start_time, m_select_end_time);
+    update();
+}
+
+void ProfileTimelineWidget::mouseup_event(GUI::MouseEvent& event)
+{
+    if (event.button() != GUI::MouseButton::Left)
+        return;
+
+    m_selecting = false;
+    if (m_select_start_time == m_select_end_time)
+        m_profile.clear_timestamp_filter_range();
+}
diff --git a/Userland/DevTools/Profiler/ProfileTimelineWidget.h b/Userland/DevTools/Profiler/ProfileTimelineWidget.h
new file mode 100644
index 0000000000..056e07769e
--- /dev/null
+++ b/Userland/DevTools/Profiler/ProfileTimelineWidget.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibGUI/Frame.h>
+
+class Profile;
+
+class ProfileTimelineWidget final : public GUI::Frame {
+    C_OBJECT(ProfileTimelineWidget)
+public:
+    virtual ~ProfileTimelineWidget() override;
+
+private:
+    virtual void paint_event(GUI::PaintEvent&) override;
+    virtual void mousedown_event(GUI::MouseEvent&) override;
+    virtual void mousemove_event(GUI::MouseEvent&) override;
+    virtual void mouseup_event(GUI::MouseEvent&) override;
+
+    explicit ProfileTimelineWidget(Profile&);
+
+    u64 timestamp_at_x(int x) const;
+
+    Profile& m_profile;
+
+    bool m_selecting { false };
+    u64 m_select_start_time { 0 };
+    u64 m_select_end_time { 0 };
+};
diff --git a/Userland/DevTools/Profiler/main.cpp b/Userland/DevTools/Profiler/main.cpp
new file mode 100644
index 0000000000..5f801936c0
--- /dev/null
+++ b/Userland/DevTools/Profiler/main.cpp
@@ -0,0 +1,220 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Profile.h"
+#include "ProfileTimelineWidget.h"
+#include <LibCore/ArgsParser.h>
+#include <LibCore/ElapsedTimer.h>
+#include <LibCore/EventLoop.h>
+#include <LibCore/ProcessStatisticsReader.h>
+#include <LibCore/Timer.h>
+#include <LibGUI/Action.h>
+#include <LibGUI/Application.h>
+#include <LibGUI/BoxLayout.h>
+#include <LibGUI/Button.h>
+#include <LibGUI/Desktop.h>
+#include <LibGUI/Label.h>
+#include <LibGUI/Menu.h>
+#include <LibGUI/MenuBar.h>
+#include <LibGUI/MessageBox.h>
+#include <LibGUI/Model.h>
+#include <LibGUI/ProcessChooser.h>
+#include <LibGUI/Splitter.h>
+#include <LibGUI/TableView.h>
+#include <LibGUI/TreeView.h>
+#include <LibGUI/Window.h>
+#include <serenity.h>
+#include <stdio.h>
+#include <string.h>
+
+static bool generate_profile(pid_t& pid);
+
+int main(int argc, char** argv)
+{
+    Core::ArgsParser args_parser;
+    int pid = 0;
+    args_parser.add_option(pid, "PID to profile", "pid", 'p', "PID");
+    args_parser.parse(argc, argv, false);
+
+    auto app = GUI::Application::construct(argc, argv);
+    auto app_icon = GUI::Icon::default_icon("app-profiler");
+
+    String path;
+    if (argc != 2) {
+        if (!generate_profile(pid))
+            return 0;
+        path = String::formatted("/proc/{}/perf_events", pid);
+    } else {
+        path = argv[1];
+    }
+
+    auto profile_or_error = Profile::load_from_perfcore_file(path);
+    if (profile_or_error.is_error()) {
+        GUI::MessageBox::show(nullptr, profile_or_error.error(), "Profiler", GUI::MessageBox::Type::Error);
+        return 0;
+    }
+
+    auto& profile = profile_or_error.value();
+
+    auto window = GUI::Window::construct();
+    window->set_title("Profiler");
+    window->set_icon(app_icon.bitmap_for_size(16));
+    window->resize(800, 600);
+
+    auto& main_widget = window->set_main_widget<GUI::Widget>();
+    main_widget.set_fill_with_background_color(true);
+    main_widget.set_layout<GUI::VerticalBoxLayout>();
+
+    main_widget.add<ProfileTimelineWidget>(*profile);
+
+    auto& bottom_splitter = main_widget.add<GUI::VerticalSplitter>();
+
+    auto& tree_view = bottom_splitter.add<GUI::TreeView>();
+    tree_view.set_should_fill_selected_rows(true);
+    tree_view.set_column_headers_visible(true);
+    tree_view.set_model(profile->model());
+
+    auto& disassembly_view = bottom_splitter.add<GUI::TableView>();
+
+    tree_view.on_selection = [&](auto& index) {
+        profile->set_disassembly_index(index);
+        disassembly_view.set_model(profile->disassembly_model());
+    };
+
+    auto menubar = GUI::MenuBar::construct();
+    auto& app_menu = menubar->add_menu("Profiler");
+    app_menu.add_action(GUI::CommonActions::make_quit_action([&](auto&) { app->quit(); }));
+
+    auto& view_menu = menubar->add_menu("View");
+
+    auto update_window_title = [&](auto title, bool is_checked) {
+        StringBuilder name;
+        name.append("Profiler");
+        if (is_checked) {
+            name.append(" - ");
+            name.append(title);
+        }
+        window->set_title(name.to_string());
+    };
+
+    auto invert_action = GUI::Action::create_checkable("Invert tree", { Mod_Ctrl, Key_I }, [&](auto& action) {
+        profile->set_inverted(action.is_checked());
+        update_window_title("Invert tree", action.is_checked());
+    });
+    invert_action->set_checked(false);
+    view_menu.add_action(invert_action);
+
+    auto top_functions_action = GUI::Action::create_checkable("Top functions", { Mod_Ctrl, Key_T }, [&](auto& action) {
+        profile->set_show_top_functions(action.is_checked());
+        update_window_title("Top functions", action.is_checked());
+    });
+    top_functions_action->set_checked(false);
+    view_menu.add_action(top_functions_action);
+
+    auto percent_action = GUI::Action::create_checkable("Show percentages", { Mod_Ctrl, Key_P }, [&](auto& action) {
+        profile->set_show_percentages(action.is_checked());
+        tree_view.update();
+        disassembly_view.update();
+        update_window_title("Show percentages", action.is_checked());
+    });
+    percent_action->set_checked(false);
+    view_menu.add_action(percent_action);
+
+    auto& help_menu = menubar->add_menu("Help");
+    help_menu.add_action(GUI::CommonActions::make_about_action("Profiler", app_icon, window));
+
+    app->set_menubar(move(menubar));
+
+    window->show();
+    return app->exec();
+}
+
+static bool prompt_to_stop_profiling(pid_t pid, const String& process_name)
+{
+    auto window = GUI::Window::construct();
+    window->set_title(String::formatted("Profiling {}({})", process_name, pid));
+    window->resize(240, 100);
+    window->set_icon(Gfx::Bitmap::load_from_file("/res/icons/16x16/app-profiler.png"));
+    window->center_on_screen();
+
+    auto& widget = window->set_main_widget<GUI::Widget>();
+    widget.set_fill_with_background_color(true);
+    auto& layout = widget.set_layout<GUI::VerticalBoxLayout>();
+    layout.set_margins(GUI::Margins(0, 0, 0, 16));
+
+    auto& timer_label = widget.add<GUI::Label>("...");
+    Core::ElapsedTimer clock;
+    clock.start();
+    auto update_timer = Core::Timer::construct(100, [&] {
+        timer_label.set_text(String::format("%.1f seconds", (float)clock.elapsed() / 1000.0f));
+    });
+
+    auto& stop_button = widget.add<GUI::Button>("Stop");
+    stop_button.set_fixed_size(140, 22);
+    stop_button.on_click = [&](auto) {
+        GUI::Application::the()->quit();
+    };
+
+    window->show();
+    return GUI::Application::the()->exec() == 0;
+}
+
+bool generate_profile(pid_t& pid)
+{
+    if (!pid) {
+        auto process_chooser = GUI::ProcessChooser::construct("Profiler", "Profile", Gfx::Bitmap::load_from_file("/res/icons/16x16/app-profiler.png"));
+        if (process_chooser->exec() == GUI::Dialog::ExecCancel)
+            return false;
+        pid = process_chooser->pid();
+    }
+
+    String process_name;
+
+    auto all_processes = Core::ProcessStatisticsReader::get_all();
+    if (all_processes.has_value()) {
+        if (auto it = all_processes.value().find(pid); it != all_processes.value().end())
+            process_name = it->value.name;
+        else
+            process_name = "(unknown)";
+    } else {
+        process_name = "(unknown)";
+    }
+
+    if (profiling_enable(pid) < 0) {
+        int saved_errno = errno;
+        GUI::MessageBox::show(nullptr, String::formatted("Unable to profile process {}({}): {}", process_name, pid, strerror(saved_errno)), "Profiler", GUI::MessageBox::Type::Error);
+        return false;
+    }
+
+    if (!prompt_to_stop_profiling(pid, process_name))
+        return false;
+
+    if (profiling_disable(pid) < 0) {
+        return false;
+    }
+
+    return true;
+}