[PATCH bpf] selftests/bpf: Use asm constraint "m" for LoongArch

[Tiezhu Yang]

Currently, LoongArch LLVM does not support the constraint "o" and no plan
to support it, it only supports the similar constraint "m", so change the
constraints from "nor" in the "else" case to arch-specific "nmr" to avoid
the build error such as "unexpected asm memory constraint" for LoongArch.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 630301b0d59d ("selftests/bpf: Add basic USDT selftests")
Link: https://llvm.org/docs/LangRef.html#supported-constraint-code-list
Link: https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/LoongArch/LoongArchISelDAGToDAG.cpp#L172
Suggested-by: Weining Lu <luweining@xxxxxxxxxxx>
Suggested-by: Li Chen <chenli@xxxxxxxxxxx>
Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
---
 tools/testing/selftests/bpf/sdt.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/bpf/sdt.h b/tools/testing/selftests/bpf/sdt.h
index ca0162b4dc57..1fcfa5160231 100644
--- a/tools/testing/selftests/bpf/sdt.h
+++ b/tools/testing/selftests/bpf/sdt.h
@@ -102,6 +102,8 @@
 # define STAP_SDT_ARG_CONSTRAINT        nZr
 # elif defined __arm__
 # define STAP_SDT_ARG_CONSTRAINT        g
+# elif defined __loongarch__
+# define STAP_SDT_ARG_CONSTRAINT        nmr
 # else
 # define STAP_SDT_ARG_CONSTRAINT        nor
 # endif
-- 
2.42.0