AOSCOS: enable memfd_secret for LoongArch64

Loongarch64 is marked ARCH_HAS_SET_DIRECT_MAP by Chen Huacai. So we can use
memfd_secret for this architecture. This commit has enabled it, and it is
kselftest passed.

Signed-off-by: Lain "Fearyncess" Yang <fsf@live.com>

Author: Fearyncess

arch/loongarch/include/asm/unistd.h

@@ -10,5 +10,6 @@
 
 #define __ARCH_WANT_NEW_STAT
 #define __ARCH_WANT_SYS_CLONE
+#define __ARCH_WANT_MEMFD_SECRET
 
 #define NR_syscalls (__NR_syscalls)

arch/loongarch/kernel/Makefile.syscalls

@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 
-# No special ABIs on loongarch so far
-syscall_abis_64 +=
+# Add memfd_secret explictly
+syscall_abis_64 += memfd_secret

tools/testing/selftests/mm/Makefile

@@ -72,7 +72,7 @@ TEST_GEN_FILES += madv_populate
 TEST_GEN_FILES += map_fixed_noreplace
 TEST_GEN_FILES += map_hugetlb
 TEST_GEN_FILES += map_populate
-ifneq (,$(filter $(ARCH),arm64 riscv riscv64 x86 x86_64))
+ifneq (,$(filter $(ARCH),arm64 riscv riscv64 x86 x86_64 loongarch64))
 TEST_GEN_FILES += memfd_secret
 endif
 TEST_GEN_FILES += migration