bpf: fix a couple of issues related to arm64

The linux arm64 header linux:arch/arm64/include/asm/sysreg.h
contains asm statement outside the function,

========
asm(
"       .irp    num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n"
"       .equ    .L__reg_num_x\\num, \\num\n"
"       .endr\n"
"       .equ    .L__reg_num_xzr, 31\n"
"\n"
"       .macro  mrs_s, rt, sreg\n"
        __emit_inst(0xd5200000|(\\sreg)|(.L__reg_num_\\rt))
"       .endm\n"
"\n"
"       .macro  msr_s, sreg, rt\n"
        __emit_inst(0xd5000000|(\\sreg)|(.L__reg_num_\\rt))
"       .endm\n"
);
========

The compiler cannot remove them since they are file scope.
This patch adds bpf asm parser to handle this, otherwise,
llvm will complain with compilation failure. Since none of
macros/defines are used in bpf program, there is no impact
in compilation result.

Another change is to add AARCH64 value to ld_cache processing.
The value is taken from glibc:sysdeps/generic/ldconfig.h.
Signed-off-by: Yonghong Song <yhs@fb.com>

cmake/clang_libs.cmake

@@ -9,6 +9,7 @@ if (${_llvm_coroutines} GREATER -1)
   list(APPEND llvm_raw_libs coroutines)
 endif()
 if (${LLVM_PACKAGE_VERSION} VERSION_GREATER "5")
+  list(APPEND llvm_raw_libs bpfasmparser)
   list(APPEND llvm_raw_libs bpfdisassembler)
 endif()
 llvm_map_components_to_libnames(_llvm_libs ${llvm_raw_libs})

src/cc/bcc_proc.c

@@ -311,6 +311,7 @@ static int load_ld_cache(const char *cache_path) {
 #define ABI_X8664_LIB64 0x0300
 #define ABI_S390_LIB64 0x0400
 #define ABI_POWERPC_LIB64 0x0500
+#define ABI_AARCH64_LIB64 0x0a00
 
 static bool match_so_flags(int flags) {
   if ((flags & FLAG_TYPE_MASK) != TYPE_ELF_LIBC6)
@@ -322,6 +323,7 @@ static bool match_so_flags(int flags) {
   case ABI_X8664_LIB64:
   case ABI_S390_LIB64:
   case ABI_POWERPC_LIB64:
+  case ABI_AARCH64_LIB64:
     return (sizeof(void *) == 8);
   }
 

src/cc/bpf_module.cc

@@ -111,6 +111,7 @@ BPFModule::BPFModule(unsigned flags, TableStorage *ts)
   LLVMInitializeBPFTargetInfo();
   LLVMInitializeBPFAsmPrinter();
 #if LLVM_MAJOR_VERSION >= 6
+  LLVMInitializeBPFAsmParser();
   if (flags & DEBUG_SOURCE)
     LLVMInitializeBPFDisassembler();
 #endif