[Lldb-commits] [lldb] [lldb][FreeBSDKernel] Implement trapframe unwinding (PR #192184)

[David Spickett via lldb-commits]

================
@@ -0,0 +1,260 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "PlatformFreeBSDKernel.h"
+
+#include "lldb/Core/Module.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Symbol/Symbol.h"
+#include "lldb/Symbol/Symtab.h"
+#include "lldb/Symbol/UnwindPlan.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Utility/LLDBLog.h"
+#include "lldb/Utility/Log.h"
+#include "lldb/Utility/StreamString.h"
+#include "llvm/TargetParser/Triple.h"
+
+#include <set>
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::platform_freebsdkernel;
+
+LLDB_PLUGIN_DEFINE(PlatformFreeBSDKernel)
+
+static uint32_t g_initialize_count = 0;
+
+PlatformFreeBSDKernel::PlatformFreeBSDKernel() : Platform(/*is_host=*/false) {
+  const llvm::Triple::ArchType arches[] = {
+      llvm::Triple::arm,     // arm32 (legacy)
+      llvm::Triple::aarch64, // arm64
+      llvm::Triple::ppc64le, // powerpc64le
+      llvm::Triple::riscv64, // riscv64
+      llvm::Triple::x86,     // i386 (legacy)
+      llvm::Triple::x86_64,  // amd64
+  };
+
+  for (auto arch : arches) {
+    ArchSpec spec;
+    spec.SetTriple(llvm::Triple(llvm::Triple::getArchTypeName(arch), "unknown",
+                                "freebsd"));
+    m_supported_architectures.push_back(spec);
+  }
+}
+
+void PlatformFreeBSDKernel::Initialize() {
+  Platform::Initialize();
+  if (g_initialize_count++ == 0) {
+    PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                  GetPluginDescriptionStatic(), CreateInstance,
+                                  nullptr);
+  }
+}
+
+void PlatformFreeBSDKernel::Terminate() {
+  if (g_initialize_count > 0) {
+    if (--g_initialize_count == 0)
+      PluginManager::UnregisterPlugin(CreateInstance);
+  }
+  Platform::Terminate();
+}
+
+lldb::PlatformSP PlatformFreeBSDKernel::CreateInstance(bool force,
+                                                       const ArchSpec *arch) {
+  // PlatformFreeBSDKernel is never auto-selected. ProcessFreeBSDKernelCore sets
+  // this platform explicitly (force=true).
+  if (!force)
+    return nullptr;
+  return std::make_shared<PlatformFreeBSDKernel>();
+}
+
+void PlatformFreeBSDKernel::GetStatus(Stream &strm) {
+  Platform::GetStatus(strm);
+  strm.Printf("  Kernel Mode: yes\n");
+}
+
+std::vector<ArchSpec> PlatformFreeBSDKernel::GetSupportedArchitectures(
+    const ArchSpec &process_host_arch) {
+  return m_supported_architectures;
+}
+
+bool PlatformFreeBSDKernel::IsCompatibleArchitecture(
+    const ArchSpec &arch, const ArchSpec &process_host_arch,
+    ArchSpec::MatchType match, ArchSpec *compatible_arch_ptr) {
+  for (const auto &supported : m_supported_architectures) {
+    if (arch.IsCompatibleMatch(supported)) {
+      if (compatible_arch_ptr)
+        *compatible_arch_ptr = supported;
+      return true;
+    }
+  }
+  return false;
+}
+
+lldb::UnwindPlanSP
+PlatformFreeBSDKernel::GetTrapHandlerUnwindPlan(const ArchSpec &arch,
+                                                ConstString name) {
+  switch (arch.GetMachine()) {
+  case llvm::Triple::aarch64:
+    return GetTrapframeUnwindPlan_arm64(name);
+  case llvm::Triple::ppc64le:
+    return GetTrapframeUnwindPlan_ppc64le(name);
+  case llvm::Triple::riscv64:
+    return GetTrapframeUnwindPlan_riscv64(name);
+  case llvm::Triple::x86_64:
+    return GetTrapframeUnwindPlan_x86_64(name);
+
+  // UnwindPlan is not implemented for the archs below as they are not
+  // expressible as a static UnwindPlan.
+  case llvm::Triple::arm:
+    // SP/LR offsets depend on saved PSR mode bits (runtime memory read
+    // required.
+  case llvm::Triple::x86:
+    // Trapframe base depends on stub identity, kernel version opcode probe, and
+    // CPL of the interrupted context.
+  default:
+    return {};
+  }
+}
+
+void PlatformFreeBSDKernel::CalculateTrapHandlerSymbolNames() {
+  // Intentionally empty. All trap handler names are populated in
+  // PopulateTrapHandlerNames() once the target architecture is known.
+  // This override exists only to suppress the default implementation.
+}
+
+void PlatformFreeBSDKernel::PopulateTrapHandlerNames(Target &target) {
+  std::lock_guard<std::mutex> guard(m_mutex);
+  if (m_trap_handlers_calculated)
+    return;
+  m_trap_handlers_calculated = true;
+
+  ModuleSP kernel_module = target.GetExecutableModule();
+  if (!kernel_module)
+    return;
+
+  const llvm::Triple::ArchType arch =
+      target.GetArchitecture().GetTriple().getArch();
+
+  // List trapframe sniffers from
+  // https://cgit.freebsd.org/ports/tree/devel/gdb/files/kgdb/<arch>-kern.c
+  switch (arch) {
+  case llvm::Triple::aarch64:
+  case llvm::Triple::x86:
+  case llvm::Triple::x86_64:
+    m_trap_handlers.push_back(ConstString("fork_trampoline"));
+    break;
+  default:
+    break;
+  }
+
+  switch (arch) {
+  case llvm::Triple::aarch64:
+    // From aarch64_fbsd_trapframe_sniffer in kgdb.
+    m_trap_handlers.push_back(ConstString("handle_el1h_sync"));
+    m_trap_handlers.push_back(ConstString("handle_el1h_irq"));
+    m_trap_handlers.push_back(ConstString("handle_el0_sync"));
+    m_trap_handlers.push_back(ConstString("handle_el0_irq"));
+    m_trap_handlers.push_back(ConstString("handle_el0_error"));
+    m_trap_handlers.push_back(ConstString("fork_trampoline"));
+    break;
+
+  case llvm::Triple::arm:
+    // From arm_fbsd_trapframe_sniffer in kgdb.
+    m_trap_handlers.push_back(ConstString("data_abort_entry"));
+    m_trap_handlers.push_back(ConstString("prefetch_abort_entry"));
+    m_trap_handlers.push_back(ConstString("undefined_entry"));
+    m_trap_handlers.push_back(ConstString("exception_exit"));
+    m_trap_handlers.push_back(ConstString("irq_entry"));
+    m_trap_handlers.push_back(ConstString("swi_entry"));
+    m_trap_handlers.push_back(ConstString("swi_exit"));
+    break;
+
+  case llvm::Triple::ppc64le:
+    // From ppcfbsd_trapframe_sniffer in kgdb.
+    m_trap_handlers.push_back(ConstString("trapagain"));
+    m_trap_handlers.push_back(ConstString("trapexit"));
+    m_trap_handlers.push_back(ConstString("dbtrap"));
+    break;
+
+  case llvm::Triple::riscv64:
+    // From riscv_fbsd_trapframe_sniffer in kgdb.
+    m_trap_handlers.push_back(ConstString("cpu_exception_handler_user"));
+    m_trap_handlers.push_back(ConstString("cpu_exception_handler_supervisor"));
+    break;
+
+  case llvm::Triple::x86:
+    // Fixed names from i386fbsd_trapframe_sniffer in kgdb.
+    m_trap_handlers.push_back(ConstString("calltrap"));
+    m_trap_handlers.push_back(ConstString("fork_trampoline"));
+    break;
+
+  case llvm::Triple::x86_64:
+    // Fixed names from amd64fbsd_trapframe_sniffer in kgdb.
+    m_trap_handlers.push_back(ConstString("calltrap"));
+    m_trap_handlers.push_back(ConstString("fast_syscall_common"));
+    m_trap_handlers.push_back(ConstString("fork_trampoline"));
+    m_trap_handlers.push_back(ConstString("mchk_calltrap"));
+    m_trap_handlers.push_back(ConstString("nmi_calltrap"));
+    break;
+
+  default:
----------------
DavidSpickett wrote:

```
default:
  assert(false && "Unexpected architecture for PlatformFreeBSDKernel plugin");
  break;
```

https://github.com/llvm/llvm-project/pull/192184