riscv: Enable seccomp architecture tracking

To enable seccomp constant action bitmaps, we need to have a static
mapping to the audit architecture and system call table size. Add these
for riscv.
Signed-off-by: NYiFei Zhu <yifeifz2@illinois.edu>
Signed-off-by: NKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/58ef925d00505cbb77478fa6bd2b48ab2d902460.1605101222.git.yifeifz2@illinois.edu

arch/riscv/include/asm/seccomp.h

@@ -7,4 +7,14 @@
 
 #include <asm-generic/seccomp.h>
 
+#ifdef CONFIG_64BIT
+# define SECCOMP_ARCH_NATIVE		AUDIT_ARCH_RISCV64
+# define SECCOMP_ARCH_NATIVE_NR		NR_syscalls
+# define SECCOMP_ARCH_NATIVE_NAME	"riscv64"
+#else /* !CONFIG_64BIT */
+# define SECCOMP_ARCH_NATIVE		AUDIT_ARCH_RISCV32
+# define SECCOMP_ARCH_NATIVE_NR		NR_syscalls
+# define SECCOMP_ARCH_NATIVE_NAME	"riscv32"
+#endif
+
 #endif /* _ASM_SECCOMP_H */