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Kernel+LibC: Add sys$perf_register_string()

This syscall allows userspace to register a keyed string that appears in
a new "strings" JSON object in profile output.

This will be used to add custom strings to profile signposts. :^)
This commit is contained in:
Andreas Kling 2021-08-11 20:28:29 +02:00
parent 00b11d7577
commit 4657c79143
7 changed files with 43 additions and 0 deletions

View file

@ -131,6 +131,7 @@ enum class NeedsBigProcessLock {
S(munmap, NeedsBigProcessLock::Yes) \
S(open, NeedsBigProcessLock::Yes) \
S(perf_event, NeedsBigProcessLock::Yes) \
S(perf_register_string, NeedsBigProcessLock::Yes) \
S(pipe, NeedsBigProcessLock::Yes) \
S(pledge, NeedsBigProcessLock::Yes) \
S(poll, NeedsBigProcessLock::Yes) \

View file

@ -166,6 +166,13 @@ PerformanceEvent& PerformanceEventBuffer::at(size_t index)
template<typename Serializer>
bool PerformanceEventBuffer::to_json_impl(Serializer& object) const
{
{
auto strings = object.add_object("strings");
for (auto& it : m_strings) {
strings.add(String::number(it.key), it.value->view());
}
}
auto array = object.add_array("events");
bool seen_first_sample = false;
for (size_t i = 0; i < m_count; ++i) {
@ -298,4 +305,13 @@ void PerformanceEventBuffer::add_process(const Process& process, ProcessEventTyp
}
}
KResult PerformanceEventBuffer::register_string(FlatPtr string_id, NonnullOwnPtr<KString> string)
{
m_strings.set(string_id, move(string));
// FIXME: Switch m_strings to something that can signal allocation failure,
// and then propagate such failures here.
return KSuccess;
}
}

View file

@ -120,6 +120,8 @@ public:
void add_process(const Process&, ProcessEventType event_type);
KResult register_string(FlatPtr string_id, NonnullOwnPtr<KString>);
private:
explicit PerformanceEventBuffer(NonnullOwnPtr<KBuffer>);
@ -130,6 +132,8 @@ private:
size_t m_count { 0 };
NonnullOwnPtr<KBuffer> m_buffer;
HashMap<FlatPtr, NonnullOwnPtr<KString>> m_strings;
};
extern bool g_profiling_all_threads;

View file

@ -400,6 +400,7 @@ public:
KResultOr<FlatPtr> sys$pledge(Userspace<const Syscall::SC_pledge_params*>);
KResultOr<FlatPtr> sys$unveil(Userspace<const Syscall::SC_unveil_params*>);
KResultOr<FlatPtr> sys$perf_event(int type, FlatPtr arg1, FlatPtr arg2);
KResultOr<FlatPtr> sys$perf_register_string(FlatPtr string_id, Userspace<char const*>, size_t);
KResultOr<FlatPtr> sys$get_stack_bounds(Userspace<FlatPtr*> stack_base, Userspace<size_t*> stack_size);
KResultOr<FlatPtr> sys$ptrace(Userspace<const Syscall::SC_ptrace_params*>);
KResultOr<FlatPtr> sys$sendfd(int sockfd, int fd);

View file

@ -21,4 +21,18 @@ KResultOr<FlatPtr> Process::sys$perf_event(int type, FlatPtr arg1, FlatPtr arg2)
return events_buffer->append(type, arg1, arg2, nullptr);
}
KResultOr<FlatPtr> Process::sys$perf_register_string(FlatPtr string_id, Userspace<char const*> user_string, size_t user_string_length)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
auto* events_buffer = current_perf_events_buffer();
if (!events_buffer)
return KSuccess;
auto string_or_error = try_copy_kstring_from_user(user_string, user_string_length);
if (string_or_error.is_error())
return string_or_error.error();
return events_buffer->register_string(string_id, string_or_error.release_value());
}
}