Fix up handling of libunwind in CMake. (netdata#19451)

* Fix up handling of libunwind in CMake.

- Fix the questionable default handling of CMAKE_SYSTEM_PROCESSOR so
  that it reliably reflects the target architecture.
- Add a case for handling 32-bit x86 builds with libunwind.
- Tweak the match cases for the various architectures to be more
  reliable.

* Fix libbpf usage of CMAKE_SYSTEM_PROCESSOR.

CMakeLists.txt

@@ -12,6 +12,8 @@ project(netdata
         HOMEPAGE_URL "https://www.netdata.cloud"
         LANGUAGES C CXX)
 include(CMakeDependentOption)
+include(NetdataUtil)
+netdata_fixup_system_processor()
 
 if(DEFINED BUILD_SHARED_LIBS)
     if(NOT BUILD_SHARED_LIBS)
@@ -2167,11 +2169,13 @@ if(ENABLE_LIBUNWIND)
 
     if(CMAKE_SYSTEM_PROCESSOR MATCHES "(x86_64)|(amd64)")
       target_link_libraries(libnetdata PUBLIC PkgConfig::LIBUNWIND -lunwind-x86_64)
-    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm64|aarch64")
+    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^i?.86")
+      target_link_libraries(libnetdata PUBLIC PkgCOnfig::LIBUNWIND -lunwind-x86)
+    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "(arm64)|(aarch64)")
       target_link_libraries(libnetdata PUBLIC PkgConfig::LIBUNWIND -lunwind-aarch64)
     elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm")
       target_link_libraries(libnetdata PUBLIC PkgConfig::LIBUNWIND -lunwind-arm)
-    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "powerpc|ppc")
+    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "p(ower)?pc64")
       target_link_libraries(libnetdata PUBLIC PkgConfig::LIBUNWIND -lunwind-ppc64)
     else()
       message(WARNING "Unknown architecture ${CMAKE_SYSTEM_PROCESSOR} for libunwind. Stack traces may not work.")

packaging/cmake/Modules/NetdataLibBPF.cmake

@@ -59,7 +59,7 @@ function(netdata_bundle_libbpf)
 
     set(_libbpf_lib_dir lib)
 
-    if(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
+    if(CMAKE_SYSTEM_PROCESSOR MATCHES "(x86_64)|(amd64)")
         set(_libbpf_lib_dir lib64)
     endif()
 

packaging/cmake/Modules/NetdataUtil.cmake

@@ -3,6 +3,30 @@
 
 include_guard()
 
+# Fix up CMAKE_SYSTEM_PROCESSOR to actually match the build target
+function(netdata_fixup_system_processor)
+  if(OS_WINDOWS)
+    return()
+  endif()
+
+  if(CMAKE_TOOLCHAIN_FILE)
+    return()
+  endif()
+
+  execute_process(
+    COMMAND ${CMAKE_C_COMPILER} ${CMAKE_C_FLAGS} -dumpmachine
+    COMMAND cut -f 1 -d -
+    RESULT_VARIABLE return_code
+    OUTPUT_VARIABLE output_data
+  )
+
+  if(return_code EQUAL 0)
+    set(CMAKE_SYSTEM_PROCESSOR "${output_data}" PARENT_SCOPE)
+  else()
+    message(WARNING "Failed to detect target processor architecture, using CMake default")
+  endif()
+endfunction()
+
 # Determine the version of the host kernel.
 #
 # Only works on UNIX-like systems, stores the version in the cache