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https://github.com/SerenityOS/serenity
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![Idan Horowitz](/assets/img/avatar_default.png)
This allows us to eliminate a major source of infallible allocation in the Kernel, as well as lay down the groundwork for OOM fallibility in userland.
370 lines
14 KiB
C++
370 lines
14 KiB
C++
/*
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* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/JsonArraySerializer.h>
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#include <AK/JsonObjectSerializer.h>
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#include <AK/ScopeGuard.h>
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#include <Kernel/Arch/RegisterState.h>
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#include <Kernel/Arch/SmapDisabler.h>
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#include <Kernel/Arch/x86/SafeMem.h>
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#include <Kernel/FileSystem/Custody.h>
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#include <Kernel/KBufferBuilder.h>
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#include <Kernel/PerformanceEventBuffer.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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PerformanceEventBuffer::PerformanceEventBuffer(NonnullOwnPtr<KBuffer> buffer)
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: m_buffer(move(buffer))
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{
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}
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NEVER_INLINE ErrorOr<void> PerformanceEventBuffer::append(int type, FlatPtr arg1, FlatPtr arg2, StringView arg3, Thread* current_thread, FlatPtr arg4, u64 arg5, ErrorOr<FlatPtr> arg6)
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{
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FlatPtr base_pointer;
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#if ARCH(I386)
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asm volatile("movl %%ebp, %%eax"
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: "=a"(base_pointer));
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#else
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asm volatile("movq %%rbp, %%rax"
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: "=a"(base_pointer));
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#endif
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return append_with_ip_and_bp(current_thread->pid(), current_thread->tid(), 0, base_pointer, type, 0, arg1, arg2, arg3, arg4, arg5, arg6);
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}
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static Vector<FlatPtr, PerformanceEvent::max_stack_frame_count> raw_backtrace(FlatPtr bp, FlatPtr ip)
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{
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Vector<FlatPtr, PerformanceEvent::max_stack_frame_count> backtrace;
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if (ip != 0)
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backtrace.unchecked_append(ip);
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FlatPtr stack_ptr_copy;
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FlatPtr stack_ptr = bp;
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// FIXME: Figure out how to remove this SmapDisabler without breaking profile stacks.
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SmapDisabler disabler;
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// NOTE: The stack should always have kernel frames first, followed by userspace frames.
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// If a userspace frame points back into kernel memory, something is afoot.
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bool is_walking_userspace_stack = false;
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while (stack_ptr) {
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void* fault_at;
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if (!safe_memcpy(&stack_ptr_copy, (void*)stack_ptr, sizeof(FlatPtr), fault_at))
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break;
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if (!Memory::is_user_address(VirtualAddress { stack_ptr })) {
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if (is_walking_userspace_stack) {
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dbgln("SHENANIGANS! Userspace stack points back into kernel memory");
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break;
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}
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} else {
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is_walking_userspace_stack = true;
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}
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FlatPtr retaddr;
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if (!safe_memcpy(&retaddr, (void*)(stack_ptr + sizeof(FlatPtr)), sizeof(FlatPtr), fault_at))
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break;
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if (retaddr == 0)
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break;
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backtrace.unchecked_append(retaddr);
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if (backtrace.size() == PerformanceEvent::max_stack_frame_count)
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break;
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stack_ptr = stack_ptr_copy;
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}
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return backtrace;
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}
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ErrorOr<void> PerformanceEventBuffer::append_with_ip_and_bp(ProcessID pid, ThreadID tid, const RegisterState& regs,
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int type, u32 lost_samples, FlatPtr arg1, FlatPtr arg2, StringView arg3, FlatPtr arg4, u64 arg5, ErrorOr<FlatPtr> arg6)
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{
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return append_with_ip_and_bp(pid, tid, regs.ip(), regs.bp(), type, lost_samples, arg1, arg2, arg3, arg4, arg5, arg6);
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}
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ErrorOr<void> PerformanceEventBuffer::append_with_ip_and_bp(ProcessID pid, ThreadID tid,
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FlatPtr ip, FlatPtr bp, int type, u32 lost_samples, FlatPtr arg1, FlatPtr arg2, StringView arg3, FlatPtr arg4, u64 arg5, ErrorOr<FlatPtr> arg6)
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{
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if (count() >= capacity())
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return ENOBUFS;
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if ((g_profiling_event_mask & type) == 0)
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return EINVAL;
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auto* current_thread = Thread::current();
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u32 enter_count = 0;
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if (current_thread)
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enter_count = current_thread->enter_profiler();
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ScopeGuard leave_profiler([&] {
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if (current_thread)
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current_thread->leave_profiler();
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});
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if (enter_count > 0)
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return EINVAL;
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PerformanceEvent event;
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event.type = type;
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event.lost_samples = lost_samples;
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switch (type) {
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case PERF_EVENT_SAMPLE:
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break;
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case PERF_EVENT_MALLOC:
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event.data.malloc.size = arg1;
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event.data.malloc.ptr = arg2;
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break;
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case PERF_EVENT_FREE:
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event.data.free.ptr = arg1;
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break;
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case PERF_EVENT_MMAP:
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event.data.mmap.ptr = arg1;
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event.data.mmap.size = arg2;
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memset(event.data.mmap.name, 0, sizeof(event.data.mmap.name));
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if (!arg3.is_empty())
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memcpy(event.data.mmap.name, arg3.characters_without_null_termination(), min(arg3.length(), sizeof(event.data.mmap.name) - 1));
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break;
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case PERF_EVENT_MUNMAP:
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event.data.munmap.ptr = arg1;
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event.data.munmap.size = arg2;
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break;
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case PERF_EVENT_PROCESS_CREATE:
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event.data.process_create.parent_pid = arg1;
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memset(event.data.process_create.executable, 0, sizeof(event.data.process_create.executable));
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if (!arg3.is_empty()) {
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memcpy(event.data.process_create.executable, arg3.characters_without_null_termination(),
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min(arg3.length(), sizeof(event.data.process_create.executable) - 1));
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}
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break;
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case PERF_EVENT_PROCESS_EXEC:
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memset(event.data.process_exec.executable, 0, sizeof(event.data.process_exec.executable));
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if (!arg3.is_empty()) {
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memcpy(event.data.process_exec.executable, arg3.characters_without_null_termination(),
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min(arg3.length(), sizeof(event.data.process_exec.executable) - 1));
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}
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break;
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case PERF_EVENT_PROCESS_EXIT:
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break;
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case PERF_EVENT_THREAD_CREATE:
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event.data.thread_create.parent_tid = arg1;
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break;
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case PERF_EVENT_THREAD_EXIT:
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break;
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case PERF_EVENT_CONTEXT_SWITCH:
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event.data.context_switch.next_pid = arg1;
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event.data.context_switch.next_tid = arg2;
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break;
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case PERF_EVENT_KMALLOC:
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event.data.kmalloc.size = arg1;
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event.data.kmalloc.ptr = arg2;
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break;
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case PERF_EVENT_KFREE:
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event.data.kfree.size = arg1;
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event.data.kfree.ptr = arg2;
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break;
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case PERF_EVENT_PAGE_FAULT:
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break;
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case PERF_EVENT_SYSCALL:
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break;
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case PERF_EVENT_SIGNPOST:
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event.data.signpost.arg1 = arg1;
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event.data.signpost.arg2 = arg2;
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break;
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case PERF_EVENT_READ:
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event.data.read.fd = arg1;
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event.data.read.size = arg2;
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event.data.read.filename_index = arg4;
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event.data.read.start_timestamp = arg5;
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event.data.read.success = !arg6.is_error();
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break;
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default:
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return EINVAL;
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}
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auto backtrace = raw_backtrace(bp, ip);
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event.stack_size = min(sizeof(event.stack) / sizeof(FlatPtr), static_cast<size_t>(backtrace.size()));
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memcpy(event.stack, backtrace.data(), event.stack_size * sizeof(FlatPtr));
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event.pid = pid.value();
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event.tid = tid.value();
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event.timestamp = TimeManagement::the().uptime_ms();
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at(m_count++) = event;
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return {};
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}
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PerformanceEvent& PerformanceEventBuffer::at(size_t index)
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{
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VERIFY(index < capacity());
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auto* events = reinterpret_cast<PerformanceEvent*>(m_buffer->data());
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return events[index];
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}
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template<typename Serializer>
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ErrorOr<void> PerformanceEventBuffer::to_json_impl(Serializer& object) const
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{
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{
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auto strings = TRY(object.add_array("strings"));
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for (auto const& it : m_strings)
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TRY(strings.add(it->view()));
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TRY(strings.finish());
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}
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bool show_kernel_addresses = Process::current().is_superuser();
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auto array = TRY(object.add_array("events"));
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bool seen_first_sample = false;
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for (size_t i = 0; i < m_count; ++i) {
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auto const& event = at(i);
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if (!show_kernel_addresses) {
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if (event.type == PERF_EVENT_KMALLOC || event.type == PERF_EVENT_KFREE)
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continue;
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}
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auto event_object = TRY(array.add_object());
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switch (event.type) {
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case PERF_EVENT_SAMPLE:
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TRY(event_object.add("type", "sample"));
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break;
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case PERF_EVENT_MALLOC:
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TRY(event_object.add("type", "malloc"));
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TRY(event_object.add("ptr", static_cast<u64>(event.data.malloc.ptr)));
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TRY(event_object.add("size", static_cast<u64>(event.data.malloc.size)));
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break;
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case PERF_EVENT_FREE:
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TRY(event_object.add("type", "free"));
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TRY(event_object.add("ptr", static_cast<u64>(event.data.free.ptr)));
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break;
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case PERF_EVENT_MMAP:
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TRY(event_object.add("type", "mmap"));
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TRY(event_object.add("ptr", static_cast<u64>(event.data.mmap.ptr)));
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TRY(event_object.add("size", static_cast<u64>(event.data.mmap.size)));
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TRY(event_object.add("name", event.data.mmap.name));
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break;
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case PERF_EVENT_MUNMAP:
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TRY(event_object.add("type", "munmap"));
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TRY(event_object.add("ptr", static_cast<u64>(event.data.munmap.ptr)));
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TRY(event_object.add("size", static_cast<u64>(event.data.munmap.size)));
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break;
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case PERF_EVENT_PROCESS_CREATE:
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TRY(event_object.add("type", "process_create"));
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TRY(event_object.add("parent_pid", static_cast<u64>(event.data.process_create.parent_pid)));
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TRY(event_object.add("executable", event.data.process_create.executable));
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break;
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case PERF_EVENT_PROCESS_EXEC:
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TRY(event_object.add("type", "process_exec"));
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TRY(event_object.add("executable", event.data.process_exec.executable));
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break;
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case PERF_EVENT_PROCESS_EXIT:
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TRY(event_object.add("type", "process_exit"));
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break;
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case PERF_EVENT_THREAD_CREATE:
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TRY(event_object.add("type", "thread_create"));
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TRY(event_object.add("parent_tid", static_cast<u64>(event.data.thread_create.parent_tid)));
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break;
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case PERF_EVENT_THREAD_EXIT:
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TRY(event_object.add("type", "thread_exit"));
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break;
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case PERF_EVENT_CONTEXT_SWITCH:
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TRY(event_object.add("type", "context_switch"));
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TRY(event_object.add("next_pid", static_cast<u64>(event.data.context_switch.next_pid)));
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TRY(event_object.add("next_tid", static_cast<u64>(event.data.context_switch.next_tid)));
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break;
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case PERF_EVENT_KMALLOC:
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TRY(event_object.add("type", "kmalloc"));
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TRY(event_object.add("ptr", static_cast<u64>(event.data.kmalloc.ptr)));
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TRY(event_object.add("size", static_cast<u64>(event.data.kmalloc.size)));
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break;
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case PERF_EVENT_KFREE:
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TRY(event_object.add("type", "kfree"));
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TRY(event_object.add("ptr", static_cast<u64>(event.data.kfree.ptr)));
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TRY(event_object.add("size", static_cast<u64>(event.data.kfree.size)));
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break;
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case PERF_EVENT_PAGE_FAULT:
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TRY(event_object.add("type", "page_fault"));
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break;
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case PERF_EVENT_SYSCALL:
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TRY(event_object.add("type", "syscall"));
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break;
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case PERF_EVENT_SIGNPOST:
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TRY(event_object.add("type"sv, "signpost"sv));
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TRY(event_object.add("arg1"sv, event.data.signpost.arg1));
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TRY(event_object.add("arg2"sv, event.data.signpost.arg2));
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break;
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case PERF_EVENT_READ:
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TRY(event_object.add("type", "read"));
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TRY(event_object.add("fd", event.data.read.fd));
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TRY(event_object.add("size"sv, event.data.read.size));
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TRY(event_object.add("filename_index"sv, event.data.read.filename_index));
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TRY(event_object.add("start_timestamp"sv, event.data.read.start_timestamp));
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TRY(event_object.add("success"sv, event.data.read.success));
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break;
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}
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TRY(event_object.add("pid", event.pid));
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TRY(event_object.add("tid", event.tid));
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TRY(event_object.add("timestamp", event.timestamp));
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TRY(event_object.add("lost_samples", seen_first_sample ? event.lost_samples : 0));
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if (event.type == PERF_EVENT_SAMPLE)
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seen_first_sample = true;
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auto stack_array = TRY(event_object.add_array("stack"));
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for (size_t j = 0; j < event.stack_size; ++j) {
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auto address = event.stack[j];
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if (!show_kernel_addresses && !Memory::is_user_address(VirtualAddress { address }))
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address = 0xdeadc0de;
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TRY(stack_array.add(address));
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}
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TRY(stack_array.finish());
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TRY(event_object.finish());
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}
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TRY(array.finish());
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TRY(object.finish());
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return {};
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}
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ErrorOr<void> PerformanceEventBuffer::to_json(KBufferBuilder& builder) const
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{
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auto object = TRY(JsonObjectSerializer<>::try_create(builder));
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return to_json_impl(object);
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}
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OwnPtr<PerformanceEventBuffer> PerformanceEventBuffer::try_create_with_size(size_t buffer_size)
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{
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auto buffer_or_error = KBuffer::try_create_with_size(buffer_size, Memory::Region::Access::ReadWrite, "Performance events", AllocationStrategy::AllocateNow);
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if (buffer_or_error.is_error())
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return {};
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return adopt_own_if_nonnull(new (nothrow) PerformanceEventBuffer(buffer_or_error.release_value()));
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}
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ErrorOr<void> PerformanceEventBuffer::add_process(const Process& process, ProcessEventType event_type)
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{
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SpinlockLocker locker(process.address_space().get_lock());
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OwnPtr<KString> executable;
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if (process.executable())
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executable = TRY(process.executable()->try_serialize_absolute_path());
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else
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executable = TRY(KString::formatted("<{}>", process.name()));
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TRY(append_with_ip_and_bp(process.pid(), 0, 0, 0,
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event_type == ProcessEventType::Create ? PERF_EVENT_PROCESS_CREATE : PERF_EVENT_PROCESS_EXEC,
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0, process.pid().value(), 0, executable->view()));
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ErrorOr<void> result;
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process.for_each_thread([&](auto& thread) {
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result = append_with_ip_and_bp(process.pid(), thread.tid().value(),
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0, 0, PERF_EVENT_THREAD_CREATE, 0, 0, 0, nullptr);
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return result.is_error() ? IterationDecision::Break : IterationDecision::Continue;
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});
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TRY(result);
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for (auto const& region : process.address_space().regions()) {
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TRY(append_with_ip_and_bp(process.pid(), 0,
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0, 0, PERF_EVENT_MMAP, 0, region->range().base().get(), region->range().size(), region->name()));
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}
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return {};
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}
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ErrorOr<FlatPtr> PerformanceEventBuffer::register_string(NonnullOwnPtr<KString> string)
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{
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FlatPtr string_id = m_strings.size();
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TRY(m_strings.try_set(move(string)));
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return string_id;
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}
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}
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