UserspaceEmulator+LibC: Add support for Region-of-Interest profiling

Userland/DevTools/UserspaceEmulator/Emulator.cpp

@@ -30,6 +30,7 @@
 extern bool g_dump_profile;
 extern unsigned g_profile_instruction_interval;
 extern Optional<OutputFileStream> g_profile_stream;
+extern bool g_in_region_of_interest;
 
 namespace UserspaceEmulator {
 
@@ -473,6 +474,8 @@ void Emulator::dump_backtrace()
 
 void Emulator::emit_profile_sample(AK::OutputStream& output)
 {
+    if (!g_in_region_of_interest)
+        return;
     StringBuilder builder;
     timeval tv {};
     gettimeofday(&tv, nullptr);

Userland/DevTools/UserspaceEmulator/EmulatorControl.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Assertions.h>
+#include <AK/StdLibExtras.h>
+#include <serenity.h>
+
+namespace UserspaceEmulator {
+
+enum class Command {
+    MarkROIStart = 5,
+    MarkROIEnd = 6,
+};
+
+inline void control(Command command)
+{
+    emuctl(to_underlying(command), 0, 0);
+}
+
+}

Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp

@@ -30,6 +30,7 @@
 
 extern bool g_dump_profile;
 extern Optional<OutputFileStream> g_profile_stream;
+extern bool g_in_region_of_interest;
 
 namespace UserspaceEmulator {
 
@@ -1118,7 +1119,7 @@ int Emulator::virt$ioctl([[maybe_unused]] int fd, unsigned request, [[maybe_unus
 int Emulator::virt$emuctl(FlatPtr arg1, FlatPtr arg2, FlatPtr arg3)
 {
     auto* tracer = malloc_tracer();
-    if (!tracer)
+    if (arg1 <= 4 && !tracer)
         return 0;
     switch (arg1) {
     case 1:
@@ -1133,6 +1134,14 @@ int Emulator::virt$emuctl(FlatPtr arg1, FlatPtr arg2, FlatPtr arg3)
     case 4:
         tracer->target_did_change_chunk_size({}, arg3, arg2);
         return 0;
+    case 5: // mark ROI start
+        if (g_in_region_of_interest)
+            return -EINVAL;
+        g_in_region_of_interest = true;
+        return 0;
+    case 6: // mark ROI end
+        g_in_region_of_interest = false;
+        return 0;
     default:
         return -EINVAL;
     }

Userland/DevTools/UserspaceEmulator/main.cpp

@@ -18,6 +18,7 @@
 #include <string.h>
 
 bool g_report_to_debug = false;
+bool g_in_region_of_interest = true;
 bool g_dump_profile = false;
 unsigned g_profile_instruction_interval = 0;
 Optional<OutputFileStream> g_profile_stream;
@@ -28,6 +29,7 @@ int main(int argc, char** argv, char** env)
     bool pause_on_startup { false };
     String profile_dump_path;
     FILE* profile_output_file { nullptr };
+    bool enable_roi_mode { false };
 
     Core::ArgsParser parser;
     parser.set_stop_on_first_non_option(true);
@@ -36,6 +38,7 @@ int main(int argc, char** argv, char** env)
     parser.add_option(g_dump_profile, "Generate a ProfileViewer-compatible profile", "profile", 0);
     parser.add_option(g_profile_instruction_interval, "Set the profile instruction capture interval, 128 by default", "profile-interval", 'i', "#instructions");
     parser.add_option(profile_dump_path, "File path for profile dump", "profile-file", 0, "path");
+    parser.add_option(enable_roi_mode, "Enable Region-of-Interest mode for profiling", "roi", 0);
 
     parser.add_positional_argument(arguments, "Command to emulate", "command");
 
@@ -44,6 +47,9 @@ int main(int argc, char** argv, char** env)
     if (g_dump_profile && g_profile_instruction_interval == 0)
         g_profile_instruction_interval = 128;
 
+    if (enable_roi_mode)
+        g_in_region_of_interest = false;
+
     String executable_path;
     if (arguments[0].contains("/"sv))
         executable_path = Core::File::real_path_for(arguments[0]);

Userland/Libraries/LibC/serenity.cpp

@@ -151,4 +151,9 @@ u16 internet_checksum(const void* ptr, size_t count)
         checksum = (checksum & 0xffff) + (checksum >> 16);
     return htons(~checksum);
 }
+
+int emuctl(uintptr_t command, uintptr_t arg0, uintptr_t arg1)
+{
+    return syscall(SC_emuctl, command, arg0, arg1);
+}
 }

Userland/Libraries/LibC/serenity.h

@@ -129,4 +129,6 @@ int setkeymap(const char* name, const uint32_t* map, uint32_t* const shift_map,
 
 uint16_t internet_checksum(const void* ptr, size_t count);
 
+int emuctl(uintptr_t command, uintptr_t arg0, uintptr_t arg1);
+
 __END_DECLS