[libunwind][Haiku] Fix signal frame unwinding

The current unwinding implementation on Haiku is messy and broken.
1. It searches weird paths for private headers, which is breaking builds
in consuming projects, such as dotnet/runtime.
2. It does not even work, due to relying on incorrect private offsets.

This commit strips all references to private headers and ports a
working signal frame implementation. It has been tested against
`tests/signal_unwind.pass.cpp` and can go pass the signal frame.

Author: trungnt2910

libunwind/src/CMakeLists.txt

@@ -118,22 +118,6 @@ if (HAIKU)
 
   add_compile_flags("-D_DEFAULT_SOURCE")
   add_compile_flags("-DPT_GNU_EH_FRAME=PT_EH_FRAME")
-
-  find_path(LIBUNWIND_HAIKU_PRIVATE_HEADERS
-            "commpage_defs.h"
-            PATHS ${CMAKE_SYSTEM_INCLUDE_PATH}
-            PATH_SUFFIXES "/private/system"
-            NO_DEFAULT_PATH
-            REQUIRED)
-
-  include_directories(SYSTEM "${LIBUNWIND_HAIKU_PRIVATE_HEADERS}")
-  if (LIBUNWIND_TARGET_TRIPLE)
-    if (${LIBUNWIND_TARGET_TRIPLE} MATCHES "^x86_64")
-      include_directories(SYSTEM "${LIBUNWIND_HAIKU_PRIVATE_HEADERS}/arch/x86_64")
-    endif()
-  else()
-    include_directories(SYSTEM "${LIBUNWIND_HAIKU_PRIVATE_HEADERS}/arch/${CMAKE_SYSTEM_PROCESSOR}")
-  endif()
 endif ()
 
 string(REPLACE ";" " " LIBUNWIND_COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}")

libunwind/src/UnwindCursor.hpp

@@ -41,6 +41,12 @@
 #define _LIBUNWIND_CHECK_LINUX_SIGRETURN 1
 #endif
 
+#if defined(_LIBUNWIND_TARGET_HAIKU) && defined(_LIBUNWIND_TARGET_X86_64)
+#include <OS.h>
+#include <signal.h>
+#define _LIBUNWIND_CHECK_HAIKU_SIGRETURN 1
+#endif
+
 #include "AddressSpace.hpp"
 #include "CompactUnwinder.hpp"
 #include "config.h"
@@ -1015,7 +1021,7 @@ class UnwindCursor : public AbstractUnwindCursor{
   template <typename Registers> int stepThroughSigReturn(Registers &) {
     return UNW_STEP_END;
   }
-#elif defined(_LIBUNWIND_TARGET_HAIKU)
+#elif defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
   bool setInfoForSigReturn();
   int stepThroughSigReturn();
 #endif
@@ -2559,7 +2565,7 @@ int UnwindCursor<A, R>::stepWithTBTable(pint_t pc, tbtable *TBTable,
 template <typename A, typename R>
 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) ||                               \
-    defined(_LIBUNWIND_TARGET_HAIKU)
+    defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
   _isSigReturn = false;
 #endif
 
@@ -2684,7 +2690,7 @@ void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
 #endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
 
 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) ||                               \
-    defined(_LIBUNWIND_TARGET_HAIKU)
+    defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
   if (setInfoForSigReturn())
     return;
 #endif
@@ -2760,63 +2766,6 @@ int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) {
   _isSignalFrame = true;
   return UNW_STEP_SUCCESS;
 }
-
-#elif defined(_LIBUNWIND_TARGET_HAIKU) && defined(_LIBUNWIND_TARGET_X86_64)
-#include <commpage_defs.h>
-#include <signal.h>
-
-extern "C" {
-extern void *__gCommPageAddress;
-}
-
-template <typename A, typename R>
-bool UnwindCursor<A, R>::setInfoForSigReturn() {
-#if defined(_LIBUNWIND_TARGET_X86_64)
-  addr_t signal_handler =
-      (((addr_t *)__gCommPageAddress)[COMMPAGE_ENTRY_X86_SIGNAL_HANDLER] +
-       (addr_t)__gCommPageAddress);
-  addr_t signal_handler_ret = signal_handler + 45;
-#endif
-  pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
-  if (pc == signal_handler_ret) {
-    _info = {};
-    _info.start_ip = signal_handler;
-    _info.end_ip = signal_handler_ret;
-    _isSigReturn = true;
-    return true;
-  }
-  return false;
-}
-
-template <typename A, typename R>
-int UnwindCursor<A, R>::stepThroughSigReturn() {
-  _isSignalFrame = true;
-  pint_t sp = _registers.getSP();
-#if defined(_LIBUNWIND_TARGET_X86_64)
-  vregs *regs = (vregs *)(sp + 0x70);
-
-  _registers.setRegister(UNW_REG_IP, regs->rip);
-  _registers.setRegister(UNW_REG_SP, regs->rsp);
-  _registers.setRegister(UNW_X86_64_RAX, regs->rax);
-  _registers.setRegister(UNW_X86_64_RDX, regs->rdx);
-  _registers.setRegister(UNW_X86_64_RCX, regs->rcx);
-  _registers.setRegister(UNW_X86_64_RBX, regs->rbx);
-  _registers.setRegister(UNW_X86_64_RSI, regs->rsi);
-  _registers.setRegister(UNW_X86_64_RDI, regs->rdi);
-  _registers.setRegister(UNW_X86_64_RBP, regs->rbp);
-  _registers.setRegister(UNW_X86_64_R8, regs->r8);
-  _registers.setRegister(UNW_X86_64_R9, regs->r9);
-  _registers.setRegister(UNW_X86_64_R10, regs->r10);
-  _registers.setRegister(UNW_X86_64_R11, regs->r11);
-  _registers.setRegister(UNW_X86_64_R12, regs->r12);
-  _registers.setRegister(UNW_X86_64_R13, regs->r13);
-  _registers.setRegister(UNW_X86_64_R14, regs->r14);
-  _registers.setRegister(UNW_X86_64_R15, regs->r15);
-  // TODO: XMM
-#endif
-
-  return UNW_STEP_SUCCESS;
-}
 #endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
        // defined(_LIBUNWIND_TARGET_AARCH64)
 
@@ -3032,6 +2981,96 @@ int UnwindCursor<A, R>::stepThroughSigReturn(Registers_s390x &) {
 #endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
        // defined(_LIBUNWIND_TARGET_S390X)
 
+#if defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
+template <typename A, typename R>
+bool UnwindCursor<A, R>::setInfoForSigReturn() {
+  Dl_info dlinfo;
+  const auto isSignalHandler = [&](pint_t addr) {
+    if (!dladdr(reinterpret_cast<void *>(addr), &dlinfo))
+      return false;
+    if (strcmp(dlinfo.dli_fname, "commpage"))
+      return false;
+    if (dlinfo.dli_sname == NULL ||
+        strcmp(dlinfo.dli_sname, "commpage_signal_handler"))
+      return false;
+    return true;
+  };
+
+  pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
+  if (!isSignalHandler(pc))
+    return false;
+
+  pint_t start = reinterpret_cast<pint_t>(dlinfo.dli_saddr);
+
+  static size_t signalHandlerSize = 0;
+  if (signalHandlerSize == 0) {
+    size_t boundLow = 0;
+    size_t boundHigh = static_cast<size_t>(-1);
+
+    area_info areaInfo;
+    if (get_area_info(area_for(dlinfo.dli_saddr), &areaInfo) == B_OK)
+      boundHigh = areaInfo.size;
+
+    while (boundLow < boundHigh) {
+      size_t boundMid = boundLow + ((boundHigh - boundLow) / 2);
+      pint_t test = start + boundMid;
+      if (test >= start && isSignalHandler(test))
+        boundLow = boundMid + 1;
+      else
+        boundHigh = boundMid;
+    }
+
+    signalHandlerSize = boundHigh;
+  }
+
+  _info = {};
+  _info.start_ip = start;
+  _info.end_ip = start + signalHandlerSize;
+  _isSigReturn = true;
+
+  return true;
+}
+
+template <typename A, typename R>
+int UnwindCursor<A, R>::stepThroughSigReturn() {
+  _isSignalFrame = true;
+
+#if defined(_LIBUNWIND_TARGET_X86_64)
+  // Layout of the stack before function call:
+  // - signal_frame_data
+  //   + siginfo_t    (public struct, fairly stable)
+  //   + ucontext_t   (public struct, fairly stable)
+  //     - mcontext_t -> Offset 0x70, this is what we want.
+  // - frame->ip (8 bytes)
+  // - frame->bp (8 bytes). Not written by the kernel,
+  //   but the signal handler has a "push %rbp" instruction.
+  pint_t bp = this->getReg(UNW_X86_64_RBP);
+  vregs *regs = (vregs *)(bp + 0x70);
+
+  _registers.setRegister(UNW_REG_IP, regs->rip);
+  _registers.setRegister(UNW_REG_SP, regs->rsp);
+  _registers.setRegister(UNW_X86_64_RAX, regs->rax);
+  _registers.setRegister(UNW_X86_64_RDX, regs->rdx);
+  _registers.setRegister(UNW_X86_64_RCX, regs->rcx);
+  _registers.setRegister(UNW_X86_64_RBX, regs->rbx);
+  _registers.setRegister(UNW_X86_64_RSI, regs->rsi);
+  _registers.setRegister(UNW_X86_64_RDI, regs->rdi);
+  _registers.setRegister(UNW_X86_64_RBP, regs->rbp);
+  _registers.setRegister(UNW_X86_64_R8, regs->r8);
+  _registers.setRegister(UNW_X86_64_R9, regs->r9);
+  _registers.setRegister(UNW_X86_64_R10, regs->r10);
+  _registers.setRegister(UNW_X86_64_R11, regs->r11);
+  _registers.setRegister(UNW_X86_64_R12, regs->r12);
+  _registers.setRegister(UNW_X86_64_R13, regs->r13);
+  _registers.setRegister(UNW_X86_64_R14, regs->r14);
+  _registers.setRegister(UNW_X86_64_R15, regs->r15);
+  // TODO: XMM
+#endif // defined(_LIBUNWIND_TARGET_X86_64)
+
+  return UNW_STEP_SUCCESS;
+}
+#endif // defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
+
 template <typename A, typename R> int UnwindCursor<A, R>::step(bool stage2) {
   (void)stage2;
   // Bottom of stack is defined is when unwind info cannot be found.
@@ -3041,7 +3080,7 @@ template <typename A, typename R> int UnwindCursor<A, R>::step(bool stage2) {
   // Use unwinding info to modify register set as if function returned.
   int result;
 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) ||                               \
-    defined(_LIBUNWIND_TARGET_HAIKU)
+    defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
   if (_isSigReturn) {
     result = this->stepThroughSigReturn();
   } else