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serenity/Kernel/PerformanceEventBuffer.cpp
Brian Gianforcaro 83fc591cea Kernel: Generate page fault events from the kernel profiler 
Hook the kernel page fault handler and capture page fault events when
the fault has a current thread attached in TLS. We capture the eip and
ebp so we can unwind the stack and locate which pieces of code are
generating the most page faults.

Co-authored-by: Gunnar Beutner <gbeutner@serenityos.org>
2021-05-19 22:51:42 +02:00

288 lines
11 KiB
C++
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/*
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/JsonArraySerializer.h>
#include <AK/JsonObject.h>
#include <AK/JsonObjectSerializer.h>
#include <AK/ScopeGuard.h>
#include <Kernel/Arch/x86/SmapDisabler.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/KBufferBuilder.h>
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
namespace Kernel {
PerformanceEventBuffer::PerformanceEventBuffer(NonnullOwnPtr<KBuffer> buffer)
: m_buffer(move(buffer))
{
}
NEVER_INLINE KResult PerformanceEventBuffer::append(int type, FlatPtr arg1, FlatPtr arg2, const StringView& arg3, Thread* current_thread)
{
FlatPtr ebp;
asm volatile("movl %%ebp, %%eax"
: "=a"(ebp));
return append_with_eip_and_ebp(current_thread->pid(), current_thread->tid(), 0, ebp, type, 0, arg1, arg2, arg3);
}
static Vector<FlatPtr, PerformanceEvent::max_stack_frame_count> raw_backtrace(FlatPtr ebp, FlatPtr eip)
{
Vector<FlatPtr, PerformanceEvent::max_stack_frame_count> backtrace;
if (eip != 0)
backtrace.append(eip);
FlatPtr stack_ptr_copy;
FlatPtr stack_ptr = (FlatPtr)ebp;
// FIXME: Figure out how to remove this SmapDisabler without breaking profile stacks.
SmapDisabler disabler;
while (stack_ptr) {
void* fault_at;
if (!safe_memcpy(&stack_ptr_copy, (void*)stack_ptr, sizeof(FlatPtr), fault_at))
break;
FlatPtr retaddr;
if (!safe_memcpy(&retaddr, (void*)(stack_ptr + sizeof(FlatPtr)), sizeof(FlatPtr), fault_at))
break;
if (retaddr == 0)
break;
backtrace.append(retaddr);
if (backtrace.size() == PerformanceEvent::max_stack_frame_count)
break;
stack_ptr = stack_ptr_copy;
}
return backtrace;
}
KResult PerformanceEventBuffer::append_with_eip_and_ebp(ProcessID pid, ThreadID tid,
u32 eip, u32 ebp, int type, u32 lost_samples, FlatPtr arg1, FlatPtr arg2, const StringView& arg3)
{
if (count() >= capacity())
return ENOBUFS;
if ((g_profiling_event_mask & type) == 0)
return EINVAL;
auto current_thread = Thread::current();
u32 enter_count = 0;
if (current_thread)
enter_count = current_thread->enter_profiler();
ScopeGuard leave_profiler([&] {
if (current_thread)
current_thread->leave_profiler();
});
if (enter_count > 0)
return EINVAL;
PerformanceEvent event;
event.type = type;
event.lost_samples = lost_samples;
switch (type) {
case PERF_EVENT_SAMPLE:
break;
case PERF_EVENT_MALLOC:
event.data.malloc.size = arg1;
event.data.malloc.ptr = arg2;
break;
case PERF_EVENT_FREE:
event.data.free.ptr = arg1;
break;
case PERF_EVENT_MMAP:
event.data.mmap.ptr = arg1;
event.data.mmap.size = arg2;
memset(event.data.mmap.name, 0, sizeof(event.data.mmap.name));
if (!arg3.is_empty())
memcpy(event.data.mmap.name, arg3.characters_without_null_termination(), min(arg3.length(), sizeof(event.data.mmap.name) - 1));
break;
case PERF_EVENT_MUNMAP:
event.data.munmap.ptr = arg1;
event.data.munmap.size = arg2;
break;
case PERF_EVENT_PROCESS_CREATE:
event.data.process_create.parent_pid = arg1;
memset(event.data.process_create.executable, 0, sizeof(event.data.process_create.executable));
if (!arg3.is_empty()) {
memcpy(event.data.process_create.executable, arg3.characters_without_null_termination(),
min(arg3.length(), sizeof(event.data.process_create.executable) - 1));
}
break;
case PERF_EVENT_PROCESS_EXEC:
memset(event.data.process_exec.executable, 0, sizeof(event.data.process_exec.executable));
if (!arg3.is_empty()) {
memcpy(event.data.process_exec.executable, arg3.characters_without_null_termination(),
min(arg3.length(), sizeof(event.data.process_exec.executable) - 1));
}
break;
case PERF_EVENT_PROCESS_EXIT:
break;
case PERF_EVENT_THREAD_CREATE:
event.data.thread_create.parent_tid = arg1;
break;
case PERF_EVENT_THREAD_EXIT:
break;
case PERF_EVENT_CONTEXT_SWITCH:
event.data.context_switch.next_pid = arg1;
event.data.context_switch.next_tid = arg2;
break;
case PERF_EVENT_KMALLOC:
event.data.kmalloc.size = arg1;
event.data.kmalloc.ptr = arg2;
break;
case PERF_EVENT_KFREE:
event.data.kfree.size = arg1;
event.data.kfree.ptr = arg2;
break;
case PERF_EVENT_PAGE_FAULT:
break;
default:
return EINVAL;
}
auto backtrace = raw_backtrace(ebp, eip);
event.stack_size = min(sizeof(event.stack) / sizeof(FlatPtr), static_cast<size_t>(backtrace.size()));
memcpy(event.stack, backtrace.data(), event.stack_size * sizeof(FlatPtr));
event.pid = pid.value();
event.tid = tid.value();
event.timestamp = TimeManagement::the().uptime_ms();
at(m_count++) = event;
return KSuccess;
}
PerformanceEvent& PerformanceEventBuffer::at(size_t index)
{
VERIFY(index < capacity());
auto* events = reinterpret_cast<PerformanceEvent*>(m_buffer->data());
return events[index];
}
template<typename Serializer>
bool PerformanceEventBuffer::to_json_impl(Serializer& object) const
{
auto array = object.add_array("events");
bool seen_first_sample = false;
for (size_t i = 0; i < m_count; ++i) {
auto& event = at(i);
auto event_object = array.add_object();
switch (event.type) {
case PERF_EVENT_SAMPLE:
event_object.add("type", "sample");
break;
case PERF_EVENT_MALLOC:
event_object.add("type", "malloc");
event_object.add("ptr", static_cast<u64>(event.data.malloc.ptr));
event_object.add("size", static_cast<u64>(event.data.malloc.size));
break;
case PERF_EVENT_FREE:
event_object.add("type", "free");
event_object.add("ptr", static_cast<u64>(event.data.free.ptr));
break;
case PERF_EVENT_MMAP:
event_object.add("type", "mmap");
event_object.add("ptr", static_cast<u64>(event.data.mmap.ptr));
event_object.add("size", static_cast<u64>(event.data.mmap.size));
event_object.add("name", event.data.mmap.name);
break;
case PERF_EVENT_MUNMAP:
event_object.add("type", "munmap");
event_object.add("ptr", static_cast<u64>(event.data.munmap.ptr));
event_object.add("size", static_cast<u64>(event.data.munmap.size));
break;
case PERF_EVENT_PROCESS_CREATE:
event_object.add("type", "process_create");
event_object.add("parent_pid", static_cast<u64>(event.data.process_create.parent_pid));
event_object.add("executable", event.data.process_create.executable);
break;
case PERF_EVENT_PROCESS_EXEC:
event_object.add("type", "process_exec");
event_object.add("executable", event.data.process_exec.executable);
break;
case PERF_EVENT_PROCESS_EXIT:
event_object.add("type", "process_exit");
break;
case PERF_EVENT_THREAD_CREATE:
event_object.add("type", "thread_create");
event_object.add("parent_tid", static_cast<u64>(event.data.thread_create.parent_tid));
break;
case PERF_EVENT_THREAD_EXIT:
event_object.add("type", "thread_exit");
break;
case PERF_EVENT_CONTEXT_SWITCH:
event_object.add("type", "context_switch");
event_object.add("next_pid", static_cast<u64>(event.data.context_switch.next_pid));
event_object.add("next_tid", static_cast<u64>(event.data.context_switch.next_tid));
break;
case PERF_EVENT_KMALLOC:
event_object.add("type", "kmalloc");
event_object.add("ptr", static_cast<u64>(event.data.kmalloc.ptr));
event_object.add("size", static_cast<u64>(event.data.kmalloc.size));
break;
case PERF_EVENT_KFREE:
event_object.add("type", "kfree");
event_object.add("ptr", static_cast<u64>(event.data.kfree.ptr));
event_object.add("size", static_cast<u64>(event.data.kfree.size));
break;
case PERF_EVENT_PAGE_FAULT:
event_object.add("type", "page_fault");
break;
}
event_object.add("pid", event.pid);
event_object.add("tid", event.tid);
event_object.add("timestamp", event.timestamp);
event_object.add("lost_samples", seen_first_sample ? event.lost_samples : 0);
if (event.type == PERF_EVENT_SAMPLE)
seen_first_sample = true;
auto stack_array = event_object.add_array("stack");
for (size_t j = 0; j < event.stack_size; ++j) {
stack_array.add(event.stack[j]);
}
stack_array.finish();
event_object.finish();
}
array.finish();
object.finish();
return true;
}
bool PerformanceEventBuffer::to_json(KBufferBuilder& builder) const
{
JsonObjectSerializer object(builder);
return to_json_impl(object);
}
OwnPtr<PerformanceEventBuffer> PerformanceEventBuffer::try_create_with_size(size_t buffer_size)
{
auto buffer = KBuffer::try_create_with_size(buffer_size, Region::Access::Read | Region::Access::Write, "Performance events", AllocationStrategy::AllocateNow);
if (!buffer)
return {};
return adopt_own(*new PerformanceEventBuffer(buffer.release_nonnull()));
}
void PerformanceEventBuffer::add_process(const Process& process, ProcessEventType event_type)
{
ScopedSpinLock locker(process.space().get_lock());
String executable;
if (process.executable())
executable = process.executable()->absolute_path();
else
executable = String::formatted("<{}>", process.name());
[[maybe_unused]] auto rc = append_with_eip_and_ebp(process.pid(), 0, 0, 0,
event_type == ProcessEventType::Create ? PERF_EVENT_PROCESS_CREATE : PERF_EVENT_PROCESS_EXEC,
0, process.pid().value(), 0, executable);
process.for_each_thread([&](auto& thread) {
[[maybe_unused]] auto rc = append_with_eip_and_ebp(process.pid(), thread.tid().value(),
0, 0, PERF_EVENT_THREAD_CREATE, 0, 0, 0, nullptr);
});
for (auto& region : process.space().regions()) {
[[maybe_unused]] auto rc = append_with_eip_and_ebp(process.pid(), 0,
0, 0, PERF_EVENT_MMAP, 0, region->range().base().get(), region->range().size(), region->name());
}
}
}
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