Implement membarrier syscall decoding

* membarrier.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* xlat/membarrier_cmds.in: New file.
* linux/dummy.h (membarrier): Remove.
* tests/membarrier.c: New file.
* tests/membarrier.test: New test.
* tests/Makefile.am (check_PROGRAMS): Add membarrier.
(TESTS): Add membarrier.test.
* tests/.gitignore: Add membarrier.

Makefile.am

@@ -86,6 +86,7 @@ strace_SOURCES =	\
 	loop.c		\
 	lseek.c		\
 	mem.c		\
+	membarrier.c	\
 	memfd_create.c	\
 	mknod.c		\
 	mount.c		\

linux/dummy.h

@@ -37,7 +37,6 @@
 #define	sys_kcmp		printargs
 #define	sys_kexec_file_load	printargs
 #define	sys_lookup_dcookie	printargs
-#define	sys_membarrier		printargs
 #define	sys_mlock2		printargs
 #define	sys_name_to_handle_at	printargs
 #define	sys_open_by_handle_at	printargs

membarrier.c

@@ -0,0 +1,21 @@
+#include "defs.h"
+
+#include "xlat/membarrier_cmds.h"
+
+SYS_FUNC(membarrier)
+{
+	if (entering(tcp)) {
+		int cmd = tcp->u_arg[0], flags = tcp->u_arg[1];
+
+		printxval(membarrier_cmds, cmd, "MEMBARRIER_CMD_???");
+		tprintf(", %d", flags);
+
+		return cmd ? RVAL_DECODED : 0;
+	}
+
+	if (syserror(tcp) || !tcp->u_rval)
+		return 0;
+
+	tcp->auxstr = sprintflags("", membarrier_cmds, tcp->u_rval);
+	return RVAL_HEX | RVAL_STR;
+}

tests/.gitignore

@@ -18,6 +18,7 @@ ipc_msg
 ipc_msgbuf
 ipc_sem
 ipc_shm
+membarrier
 memfd_create
 mmap
 mmap64

tests/Makefile.am

@@ -31,6 +31,7 @@ check_PROGRAMS = \
 	ipc_msgbuf \
 	ipc_sem \
 	ipc_shm \
+	membarrier \
 	memfd_create \
 	mmap \
 	mmap64 \
@@ -145,6 +146,7 @@ TESTS = \
 	stat64-v.test \
 	statfs.test \
 	sysinfo.test \
+	membarrier.test \
 	memfd_create.test \
 	mmap.test \
 	mmap64.test \

tests/membarrier.c

@@ -0,0 +1,31 @@
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+int
+main(void)
+{
+#ifdef __NR_membarrier
+	if (syscall(__NR_membarrier, 3, 255) != -1)
+		return 77;
+	printf("membarrier(0x3 /* MEMBARRIER_CMD_??? */, 255) = -1 %s\n",
+	       errno == ENOSYS ?
+			"ENOSYS (Function not implemented)" :
+			"EINVAL (Invalid argument)");
+	if (errno != ENOSYS) {
+		if (syscall(__NR_membarrier, 0, 0) != 1)
+			return 1;  /* the test needs to be updated? */
+		puts("membarrier(MEMBARRIER_CMD_QUERY, 0)"
+		     " = 0x1 (MEMBARRIER_CMD_SHARED)");
+	}
+	puts("+++ exited with 0 +++");
+	return 0;
+#else
+        return 77;
+#endif
+}

tests/membarrier.test

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+# Check membarrier syscall decoding.
+
+. "${srcdir=.}/init.sh"
+
+run_prog > /dev/null
+OUT="$LOG.out"
+run_strace -a36 -emembarrier $args > "$OUT"
+match_diff "$OUT" "$LOG"
+rm -f "$OUT"
+
+exit 0

xlat/membarrier_cmds.in

@@ -0,0 +1,2 @@
+MEMBARRIER_CMD_QUERY	0
+MEMBARRIER_CMD_SHARED	1