sandbox: Add Arm64 support for seccomp-BPF

sandbox/linux/seccomp-bpf/syscall_unittest.cc

Index: sandbox/linux/seccomp-bpf/syscall_unittest.cc
diff --git a/sandbox/linux/seccomp-bpf/syscall_unittest.cc b/sandbox/linux/seccomp-bpf/syscall_unittest.cc
index 38f31e0a58ed5073f0236ec36bd7acca6c1dd5ad..54e1dda254f55d37b2195fd17697ae867d60933f 100644
--- a/sandbox/linux/seccomp-bpf/syscall_unittest.cc
+++ b/sandbox/linux/seccomp-bpf/syscall_unittest.cc
@@ -41,7 +41,7 @@ TEST(Syscall, WellKnownEntryPoint) {
 // Test that Syscall::Call(-1) is handled specially. Don't do this on ARM,
 // where syscall(-1) crashes with SIGILL. Not running the test is fine, as we
 // are still testing ARM code in the next set of tests.
-#if !defined(__arm__)
+#if !defined(__arm__) && !defined(__aarch64__)
   EXPECT_NE(Syscall::Call(-1), syscall(-1));
 #endif
 
@@ -61,6 +61,8 @@ TEST(Syscall, WellKnownEntryPoint) {
 #elif defined(__mips__)
   // Opcode for MIPS sycall is in the lower 16-bits
   EXPECT_EQ(0x0cu, (((uint32_t*)Syscall::Call(-1))[-1]) & 0x0000FFFF);
+#elif defined(__aarch64__)
+  EXPECT_EQ(0xD4000001u, ((uint32_t*)Syscall::Call(-1))[-1]);  // SVC 0
 #else
 #warning Incomplete test case; need port for target platform
 #endif
@@ -153,7 +155,8 @@ BPF_TEST(Syscall,
 
 TEST(Syscall, ComplexSyscallSixArgs) {
   int fd;
-  ASSERT_LE(0, fd = Syscall::Call(__NR_open, "/dev/null", O_RDWR, 0L));
+  ASSERT_LE(0,
+            fd = Syscall::Call(__NR_openat, AT_FDCWD, "/dev/null", O_RDWR, 0L));
 
   // Use mmap() to allocate some read-only memory
   char* addr0;
@@ -186,7 +189,9 @@ TEST(Syscall, ComplexSyscallSixArgs) {
 
   // Check that the offset argument (i.e. the sixth argument) is processed
   // correctly.
-  ASSERT_GE(fd = Syscall::Call(__NR_open, "/proc/self/exe", O_RDONLY, 0L), 0);
+  ASSERT_GE(
+      fd = Syscall::Call(__NR_openat, AT_FDCWD, "/proc/self/exe", O_RDONLY, 0L),
+      0);
   char* addr2, *addr3;
   ASSERT_NE((char*)NULL,
             addr2 = reinterpret_cast<char*>(Syscall::Call(