io_uring: implement decoding of IORING_REGISTER_USE_REGISTERED_RING o…

…pcode flag

This io_uring_register opcode flag was introduced by Linux kernel commit
v6.3-rc1~209^2.

* src/xlat/uring_register_opcode_flags.in: New file.
* src/io_uring.c: Include "xlat/uring_register_opcode_flags.h".
(print_io_uring_register_opcode): New function.
(SYS_FUNC(io_uring_register)): Use it to print opcodes.
* tests/io_uring_register.c (main): Check it.
* NEWS: Mention this change.

NEWS

@@ -9,7 +9,7 @@ Noteworthy changes in release ?.? (????-??-??)
     IORING_REGISTER_FILE_ALLOC_RANGE, IORING_REGISTER_PBUF_STATUS,
     IORING_REGISTER_NAPI, and IORING_UNREGISTER_NAPI opcodes of
     io_uring_register syscall.
-  * Updated decoding of pidfd_send_signal syscall.
+  * Updated decoding of io_uring_register and pidfd_send_signal syscalls.
   * Updated lists of CAN_*, IORING_*, KEY_*, LSM_*, MPOL_*, NT_*, RWF_*,
     PIDFD_*, PTP_*, TCP_*, and *_MAGIC constants.
   * Updated lists of ioctl commands from Linux 6.9.

src/io_uring.c

@@ -22,6 +22,7 @@
 #include "xlat/uring_setup_flags.h"
 #include "xlat/uring_sqe_flags.h"
 #include "xlat/uring_register_opcodes.h"
+#include "xlat/uring_register_opcode_flags.h"
 #include "xlat/uring_register_rsrc_flags.h"
 #include "xlat/uring_restriction_opcodes.h"
 
@@ -769,23 +770,45 @@ print_ioring_unregister_napi(struct tcb *tcp, const kernel_ulong_t addr,
 	return RVAL_DECODED;
 }
 
+static void
+print_io_uring_register_opcode(struct tcb *tcp, const unsigned int opcode,
+			       const unsigned int flags)
+{
+	if (flags)
+		tprint_flags_begin();
+
+	printxval(uring_register_opcodes, opcode, "IORING_REGISTER_???");
+
+	if (flags) {
+		tprint_flags_or();
+		printflags_in(uring_register_opcode_flags, flags, NULL);
+		tprint_flags_end();
+	}
+
+}
+
 SYS_FUNC(io_uring_register)
 {
 	const int fd = tcp->u_arg[0];
-	const unsigned int opcode = tcp->u_arg[1];
+	unsigned int opcode = tcp->u_arg[1];
 	const kernel_ulong_t arg = tcp->u_arg[2];
 	const unsigned int nargs = tcp->u_arg[3];
+	const unsigned int opcode_flags =
+		opcode & IORING_REGISTER_USE_REGISTERED_RING;
+	opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
 	int rc = RVAL_DECODED;
 	int buf;
 
 	if (entering(tcp)) {
 		/* fd */
-		printfd(tcp, fd);
+		if (opcode_flags)
+			PRINT_VAL_U(fd);
+		else
+			printfd(tcp, fd);
 		tprint_arg_next();
 
 		/* opcode */
-		printxval(uring_register_opcodes, opcode,
-			  "IORING_REGISTER_???");
+		print_io_uring_register_opcode(tcp, opcode, opcode_flags);
 		tprint_arg_next();
 	}
 

src/xlat/uring_register_opcode_flags.in

@@ -0,0 +1,2 @@
+#unconditional
+IORING_REGISTER_USE_REGISTERED_RING

tests/io_uring_register.c

@@ -172,7 +172,13 @@ main(void)
 
 
 	/* Invalid op */
-	static const unsigned int invalid_ops[] = { 0xbadc0dedU, 29 };
+	static const unsigned int invalid_ops[] = { 0x7fffffffU, 29 };
+	static const struct {
+		unsigned int val;
+		const char *str;
+	} op_flags[] = {
+		{ ARG_STR(IORING_REGISTER_USE_REGISTERED_RING) },
+	};
 
 	for (size_t i = 0; i < ARRAY_SIZE(invalid_ops); i++) {
 		sys_io_uring_register(fd_null, invalid_ops[i], path_null,
@@ -181,6 +187,18 @@ main(void)
 		       NRAW(" /* IORING_REGISTER_??? */") ", %p, %u) = %s\n",
 		       fd_null, path_null, invalid_ops[i], path_null,
 		       0xdeadbeef, errstr);
+
+		for (size_t j = 0; j < ARRAY_SIZE(op_flags); ++j) {
+			sys_io_uring_register(fd_null, invalid_ops[i] |
+						       op_flags[j].val,
+					      path_null, 0xdeadbeef);
+			printf("io_uring_register(%u, %#x"
+			       NRAW(" /* IORING_REGISTER_??? */") "|" XLAT_FMT
+			       ", %p, %u) = %s\n",
+			       fd_null, invalid_ops[i],
+			       XLAT_SEL(op_flags[j].val, op_flags[j].str),
+			       path_null, 0xdeadbeef, errstr);
+		}
 	}
 
 
@@ -205,6 +223,18 @@ main(void)
 		       fd_null, path_null,
 		       XLAT_SEL(no_arg_ops[i].op, no_arg_ops[i].str),
 		       path_null, 0xdeadbeef, errstr);
+
+		for (size_t j = 0; j < ARRAY_SIZE(op_flags); ++j) {
+			sys_io_uring_register(fd_null, no_arg_ops[i].op |
+						       op_flags[j].val,
+					      path_null, 0xdeadbeef);
+			printf("io_uring_register(%u, " XLAT_FMT "|" XLAT_FMT
+			       ", %p, %u) = %s\n",
+			       fd_null,
+			       XLAT_SEL(no_arg_ops[i].op, no_arg_ops[i].str),
+			       XLAT_SEL(op_flags[j].val, op_flags[j].str),
+			       path_null, 0xdeadbeef, errstr);
+		}
 	}