[widevine] add support for arm64

without these changes, the following error is observed:

    Initialize: Failed to load library: libwidevinecdm.so: undefined symbol: __aarch64_ldadd4_acq_rel
    Unable to load widevine shared library (libwidevinecdm.so)

src/Session.cpp

@@ -140,6 +140,19 @@ void CSession::SetSupportedDecrypterURN(std::string& key_system)
  m_dllHelper = std::make_unique<kodi::tools::CDllHelper>();
  if (m_dllHelper->LoadDll(item.Path()))
  {
+#if defined(__aarch64__) && !defined(ANDROID)
+ // On linux arm64, libwidevinecdm.so depends on two dynamic symbols:
+ // __aarch64_ldadd4_acq_rel
+ // __aarch64_swp4_acq_rel
+ // These are defined in libssd_wv.so, but to make them available in the main binary's PLT,
+ // we need RTLD_GLOBAL. LoadDll() above uses RTLD_LOCAL, so we use RTLD_NOLOAD here to
+ // switch the flags from LOCAL to GLOBAL.
+ void *hdl = dlopen(item.Path().c_str(), RTLD_NOLOAD | RTLD_GLOBAL | RTLD_LAZY);
+ if (!hdl)
+ {
+ LOG::Log(LOGERROR, "Failed to reload dll in global mode: %s", dlerror());
+ }
+#endif
  CreateDecryptorInstanceFunc startup;
  if (m_dllHelper->RegisterSymbol(startup, "CreateDecryptorInstance"))
  {

wvdecrypter/wvdecrypter.cpp

@@ -23,6 +23,9 @@
 #include <thread>
 #include <vector>
 
+#if defined(__aarch64__) && !defined(ANDROID)
+#include <sys/auxv.h>
+#endif
 #include <bento4/Ap4.h>
 
 #ifndef WIDEVINECDMFILENAME
@@ -1671,6 +1674,69 @@ class WVDecrypter : public SSD_DECRYPTER
 
 extern "C" {
 
+// Linux arm64 version of libwidevinecdm.so depends on two
+// dynamic symbols. See https:/xbmc/inputstream.adaptive/issues/1128
+// These implementations are based on libgcc.a lse.S
+#if defined(__aarch64__) && !defined(ANDROID)
+static int have_lse_atomics;
+
+static void __attribute__((constructor (101))) init_have_lse_atomics()
+{
+ unsigned long hwcap = getauxval (AT_HWCAP);
+ have_lse_atomics = (hwcap & HWCAP_ATOMICS) != 0;
+}
+
+int32_t __aarch64_ldadd4_acq_rel(int32_t value, int32_t *ptr)
+{
+ int32_t ret;
+ if (have_lse_atomics) {
+ __asm__ __volatile__ (
+ ".inst 0x38200020 + 0x0000 + 0x80000000 + 0xc00000\r\n"
+ : "=&r" (ret)
+ :
+ );
+ } else {
+ __asm__ __volatile__ (
+ "0:\r\n"
+ "ldaxr w16, [%[ptr]]\r\n"
+ "add w17, w16, %w[value]\r\n"
+ "stlxr w15, w17, [%[ptr]]\r\n"
+ "cbnz w15, 0b\r\n"
+ "mov %w[result], w16\r\n"
+ : [result] "=&r" (ret)
+ : [ptr] "r" (ptr),
+ [value] "r" (value)
+ : "w15", "w16", "w17", "memory"
+ );
+ }
+ return ret;
+}
+
+int32_t __aarch64_swp4_acq_rel(int32_t value, int32_t *ptr)
+{
+ int32_t ret;
+ if (have_lse_atomics) {
+ __asm__ __volatile__ (
+ ".inst 0x38208020 + 0x80000000 + 0xc00000\r\n"
+ : "=&r" (ret)
+ :
+ );
+ } else {
+ __asm__ __volatile__ (
+ "0:\r\n"
+ "ldaxr %w[result], [%[ptr]]\r\n"
+ "stlxr w15, %w[value], [%[ptr]]\r\n"
+ "cbnz w15, 0b\r\n"
+ : [result] "=&r" (ret)
+ : [ptr] "r" (ptr),
+ [value] "r" (value)
+ : "w15", "memory"
+ );
+ }
+ return ret;
+}
+#endif
+
 #ifdef _WIN32
 #define MODULE_API __declspec(dllexport)
 #else