Work around outdated system header files on Amazon Linux

Author: adrian-prantl

lldb/cmake/modules/LLDBConfig.cmake

@@ -345,4 +345,19 @@ if ((CMAKE_SYSTEM_NAME MATCHES "Android") AND LLVM_BUILD_STATIC AND
   add_definitions(-DANDROID_USE_ACCEPT_WORKAROUND)
 endif()
 
+if (CMAKE_SYSTEM_NAME MATCHES "Linux")
+  check_cxx_source_compiles(
+    "#include <asm/ptrace.h>
+     struct user_sve_header hdr;
+     int main(void){return 0;}
+    "
+    user_sve_header_available)
+  if(user_sve_header_available)
+    set(LLDB_HAVE_USER_SVE_HEADER ON)
+    message(STATUS "AArch64 SVE support enabled.")
+  else()
+    message(STATUS "AArch64 SVE support disabled.")
+  endif()
+endif()
+
 include(LLDBGenerateConfig)

lldb/include/lldb/Host/Config.h.cmake

@@ -47,6 +47,8 @@
 
 #cmakedefine01 LLDB_EMBED_PYTHON_HOME
 
+#cmakedefine01 LLDB_HAVE_USER_SVE_HEADER
+
 #cmakedefine LLDB_PYTHON_HOME R"(${LLDB_PYTHON_HOME})"
 
 #define LLDB_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}"

lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp

@@ -60,7 +60,11 @@ NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(
   case llvm::Triple::aarch64: {
     // Configure register sets supported by this AArch64 target.
     // Read SVE header to check for SVE support.
+#if LLDB_HAVE_USER_SVE_HEADER
     struct user_sve_header sve_header;
+#else
+    struct user_sve_header sve_header {};
+#endif
     struct iovec ioVec;
     ioVec.iov_base = &sve_header;
     ioVec.iov_len = sizeof(sve_header);
@@ -205,13 +209,21 @@ NativeRegisterContextLinux_arm64::ReadRegister(const RegisterInfo *reg_info,
       if (reg == GetRegisterInfo().GetRegNumFPSR()) {
         sve_reg_num = reg;
         if (m_sve_state == SVEState::Full)
+#if LLDB_HAVE_USER_SVE_HEADER
           offset = sve::PTraceFPSROffset(sve::vq_from_vl(m_sve_header.vl));
+#else
+          offset = 0;
+#endif
         else if (m_sve_state == SVEState::FPSIMD)
           offset = sve::ptrace_fpsimd_offset + (32 * 16);
       } else if (reg == GetRegisterInfo().GetRegNumFPCR()) {
         sve_reg_num = reg;
         if (m_sve_state == SVEState::Full)
+#if LLDB_HAVE_USER_SVE_HEADER
           offset = sve::PTraceFPCROffset(sve::vq_from_vl(m_sve_header.vl));
+#else
+          offset = 0;
+#endif
         else if (m_sve_state == SVEState::FPSIMD)
           offset = sve::ptrace_fpsimd_offset + (32 * 16) + 4;
       } else {
@@ -339,13 +351,21 @@ Status NativeRegisterContextLinux_arm64::WriteRegister(
       if (reg == GetRegisterInfo().GetRegNumFPSR()) {
         sve_reg_num = reg;
         if (m_sve_state == SVEState::Full)
+#if LLDB_HAVE_USER_SVE_HEADER
           offset = sve::PTraceFPSROffset(sve::vq_from_vl(m_sve_header.vl));
+#else
+          offset = 0;
+#endif
         else if (m_sve_state == SVEState::FPSIMD)
           offset = sve::ptrace_fpsimd_offset + (32 * 16);
       } else if (reg == GetRegisterInfo().GetRegNumFPCR()) {
         sve_reg_num = reg;
         if (m_sve_state == SVEState::Full)
+#if LLDB_HAVE_USER_SVE_HEADER
           offset = sve::PTraceFPCROffset(sve::vq_from_vl(m_sve_header.vl));
+#else
+          offset = 0;
+#endif
         else if (m_sve_state == SVEState::FPSIMD)
           offset = sve::ptrace_fpsimd_offset + (32 * 16) + 4;
       } else {
@@ -917,18 +937,22 @@ void NativeRegisterContextLinux_arm64::ConfigureRegisterContext() {
     if (error.Success()) {
       // If SVE is enabled thread can switch between SVEState::FPSIMD and
       // SVEState::Full on every stop.
+#if LLDB_HAVE_USER_SVE_HEADER
       if ((m_sve_header.flags & sve::ptrace_regs_mask) ==
           sve::ptrace_regs_fpsimd)
         m_sve_state = SVEState::FPSIMD;
       else if ((m_sve_header.flags & sve::ptrace_regs_mask) ==
                sve::ptrace_regs_sve)
         m_sve_state = SVEState::Full;
+#endif
 
       // On every stop we configure SVE vector length by calling
       // ConfigureVectorLength regardless of current SVEState of this thread.
       uint32_t vq = RegisterInfoPOSIX_arm64::eVectorQuadwordAArch64SVE;
+#if LLDB_HAVE_USER_SVE_HEADER
       if (sve_vl_valid(m_sve_header.vl))
         vq = sve::vq_from_vl(m_sve_header.vl);
+#endif
 
       GetRegisterInfo().ConfigureVectorLength(vq);
       m_sve_ptrace_payload.resize(sve::PTraceSize(vq, sve::ptrace_regs_sve));