[k2] add sync backtrace (#1340)

Author: astrophysik

runtime-light/k2-platform/k2-api.h

@@ -10,6 +10,7 @@
 #include <ctime>
 #include <expected>
 #include <memory>
+#include <span>
 #include <string_view>
 #include <sys/utsname.h>
 #include <utility>
@@ -288,4 +289,8 @@ inline int32_t code_segment_offset(uint64_t* offset) noexcept {
   return k2_code_segment_offset(offset);
 }
 
+inline size_t backtrace(std::span<void*> buffer) noexcept {
+  return k2_backtrace(buffer.data(), buffer.size());
+}
+
 } // namespace k2

runtime-light/k2-platform/k2-header.h

@@ -483,7 +483,7 @@ struct SymbolInfo {
  * Note: name and filename in symbol_info are **not** null-terminated.
  * @param `addr` pointer to code instruction
  * @param `symbol_info` structure stores buffers where the name and file name will be written. The buffer
- *        lens must staisfy `name_len >= k2_symbol_name_len and filename_len >= k2_symbol_filename_len`
+ *        lens must satisfy `name_len >= k2_symbol_name_len and filename_len >= k2_symbol_filename_len`
  * `errno` options:
  * `EINVAL`  => `addr` symbol can't be resolved
  * `ENODATA` => there is no debug information for the image
@@ -547,6 +547,13 @@ int32_t k2_iconv(size_t* result, void* iconv_cd, char** inbuf, size_t* inbytesle
  */
 size_t k2_stderr_write(size_t data_len, const void* data);
 
+/**
+ * Analogue for libc backtrace. Returns a backtrace of the calling component
+ *
+ * @return backtrace size on success, `0` otherwise
+ */
+size_t k2_backtrace(void** buffer, size_t size);
+
 #ifdef __cplusplus
 }
 #endif

runtime-light/stdlib/diagnostics/backtrace.cpp

@@ -3,12 +3,13 @@
 //  Distributed under the GPL v3 License, see LICENSE.notice.txt
 
 #include <cstddef>
-#include <cstdint>
 #include <iterator>
 #include <span>
 
 #include "runtime-light/coroutine/async-stack.h"
 #include "runtime-light/coroutine/coroutine-state.h"
+#include "runtime-light/k2-platform/k2-api.h"
+#include "runtime-light/state/instance-state.h"
 #include "runtime-light/stdlib/diagnostics/backtrace.h"
 #include "runtime-light/utils/logs.h"
 
@@ -40,17 +41,19 @@ size_t async_frames(std::span<void*> addresses, kphp::coro::async_stack_frame* t
 
 } // namespace
 
-namespace kphp::diagnostic {
+namespace kphp::diagnostic::impl {
 
-size_t backtrace(std::span<void*> addresses) noexcept {
-  auto& async_stack_root{CoroutineInstanceState::get().coroutine_stack_root};
+size_t async_backtrace(std::span<void*> addresses) noexcept {
+  if (const auto* instance_state{k2::instance_state()}; instance_state != nullptr) [[likely]] {
+    const auto& async_stack_root{instance_state->coroutine_instance_state.coroutine_stack_root};
 
-  auto* const start_sync_frame{reinterpret_cast<kphp::coro::stack_frame*>(STACK_FRAME_ADDRESS)};
-  auto* const stop_sync_frame{async_stack_root.stop_sync_stack_frame};
+    auto* const start_sync_frame{reinterpret_cast<kphp::coro::stack_frame*>(STACK_FRAME_ADDRESS)};
+    auto* const stop_sync_frame{async_stack_root.stop_sync_stack_frame};
 
-  const size_t num_sync_frames{sync_frames(addresses, start_sync_frame, stop_sync_frame)};
-  const size_t num_async_frames{async_frames(addresses.subspan(num_sync_frames), async_stack_root.top_async_stack_frame)};
-  return num_sync_frames + num_async_frames;
+    const size_t num_sync_frames{sync_frames(addresses, start_sync_frame, stop_sync_frame)};
+    const size_t num_async_frames{async_frames(addresses.subspan(num_sync_frames), async_stack_root.top_async_stack_frame)};
+    return num_sync_frames + num_async_frames;
+  }
+  return 0;
 }
-
-} // namespace kphp::diagnostic
+} // namespace kphp::diagnostic::impl

runtime-light/stdlib/diagnostics/backtrace.h

@@ -15,7 +15,23 @@
 
 namespace kphp::diagnostic {
 
-size_t backtrace(std::span<void*> addresses) noexcept;
+namespace impl {
+
+size_t async_backtrace(std::span<void*> addresses) noexcept;
+
+inline size_t sync_backtrace(std::span<void*> addresses) noexcept {
+  return k2::backtrace(addresses);
+}
+
+} // namespace impl
+
+inline size_t backtrace(std::span<void*> addresses) noexcept {
+  size_t async_num_frames{impl::async_backtrace(addresses)};
+  if (async_num_frames != 0) [[likely]] {
+    return async_num_frames;
+  }
+  return impl::sync_backtrace(addresses);
+}
 
 inline auto backtrace_addresses(std::span<void* const> addresses) noexcept {
   uint64_t code_segment_offset{};