selftests/bpf: Enable timed may_goto tests for LoongArch

Enable stream_cond_break, may_goto_interaction, and verifier_may_goto_1
tests for LoongArch, aligning with recent architectural infrastructure
support (timed may_goto and arch_bpf_stack_walk JIT).

With this patch, the following tests passed on LoongArch:

  sudo ./test_progs -a stream_success/stream_cond_break
  sudo ./test_progs -a verifier_bpf_fastcall/may_goto_interaction
  sudo ./test_progs -a verifier_may_goto_1

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20260813070906.5164-1-yangtiezhu@loongson.cn

tools/testing/selftests/bpf/progs/stream.c

@@ -65,6 +65,7 @@ __arch_x86_64
 __arch_arm64
 __arch_s390x
 __arch_riscv64
+__arch_loongarch
 __success __retval(0)
 __stderr("ERROR: Timeout detected for may_goto instruction")
 __stderr("CPU: {{[0-9]+}} UID: 0 PID: {{[0-9]+}} Comm: {{.*}}")

tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c

@@ -665,6 +665,7 @@ __naked void may_goto_interaction_x86_64(void)
 SEC("raw_tp")
 __arch_arm64
 __arch_riscv64
+__arch_loongarch
 __log_level(4)
 __msg("subprog 0 (may_goto_interaction) main {{.*}} stack 24")
 /* may_goto counter at -24 */

tools/testing/selftests/bpf/progs/verifier_may_goto_1.c

@@ -12,6 +12,7 @@ __arch_x86_64
 __arch_s390x
 __arch_arm64
 __arch_riscv64
+__arch_loongarch
 __xlated("0: r0 = 1")
 __xlated("1: exit")
 __success
@@ -33,6 +34,7 @@ __arch_x86_64
 __arch_s390x
 __arch_arm64
 __arch_riscv64
+__arch_loongarch
 __xlated("0: r0 = 1")
 __xlated("1: exit")
 __success
@@ -56,6 +58,7 @@ __arch_x86_64
 __arch_s390x
 __arch_arm64
 __arch_riscv64
+__arch_loongarch
 __xlated("0: r0 = 1")
 __xlated("1: exit")
 __success
@@ -83,6 +86,7 @@ __arch_x86_64
 __arch_s390x
 __arch_arm64
 __arch_riscv64
+__arch_loongarch
 __xlated("0: *(u64 *)(r10 -16) = 65535")
 __xlated("1: *(u64 *)(r10 -8) = 0")
 __xlated("2: r12 = *(u64 *)(r10 -16)")
@@ -120,6 +124,7 @@ __arch_x86_64
 __arch_s390x
 __arch_arm64
 __arch_riscv64
+__arch_loongarch
 __success
 __retval(0)
 __naked void timed_may_goto_preserves_regs(void)