Make truss(8) work for 32-bit CloudABI executables on ARM64.

This change effectively merges the existing 64-bit support for ARM64
with the 32-on-64-bit support for AMD64.

usr.bin/truss/Makefile

@@ -13,6 +13,7 @@ ABIS+=		freebsd
 # Each ABI is expected to have an ABI.c, MACHINE_ARCH-ABI.c or
 # MACHINE_CPUARCH-ABI.c file that will be used to map the syscall arguments.
 .if ${MACHINE_ARCH} == "aarch64"
+ABIS+=		cloudabi32
 ABIS+=		cloudabi64
 .endif
 .if ${MACHINE_CPUARCH} == "i386"

usr.bin/truss/aarch64-cloudabi32.c

@@ -0,0 +1,112 @@
+/*-
+ * Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/ptrace.h>
+
+#include <machine/armreg.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <sysdecode.h>
+
+#include "truss.h"
+
+static int
+aarch64_cloudabi32_fetch_args(struct trussinfo *trussinfo, unsigned int narg)
+{
+	struct current_syscall *cs;
+	struct ptrace_io_desc iorequest;
+	struct reg regs;
+	lwpid_t tid;
+
+	if (narg > 0) {
+		/* Fetch registers, containing the address of the arguments. */
+		tid = trussinfo->curthread->tid;
+		if (ptrace(PT_GETREGS, tid, (caddr_t)&regs, 0) == -1) {
+			fprintf(trussinfo->outfile,
+			    "-- CANNOT READ REGISTERS --\n");
+			return (-1);
+		}
+
+		/* Fetch arguments. They are already padded to 64 bits. */
+		cs = &trussinfo->curthread->cs;
+		iorequest.piod_op = PIOD_READ_D;
+		iorequest.piod_offs = (void *)regs.x[2];
+		iorequest.piod_addr = cs->args;
+		iorequest.piod_len = sizeof(cs->args[0]) * narg;
+		if (ptrace(PT_IO, tid, (caddr_t)&iorequest, 0) == -1 ||
+		    iorequest.piod_len == 0)
+			return (-1);
+	}
+	return (0);
+}
+
+static int
+aarch64_cloudabi32_fetch_retval(struct trussinfo *trussinfo, long *retval,
+    int *errorp)
+{
+	struct ptrace_io_desc iorequest;
+	struct reg regs;
+	lwpid_t tid;
+
+	/* Fetch registers, containing the address of the return values. */
+	tid = trussinfo->curthread->tid;
+	if (ptrace(PT_GETREGS, tid, (caddr_t)&regs, 0) == -1) {
+		fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
+		return (-1);
+	}
+
+	if ((regs.spsr & PSR_C) == 0) {
+		/* System call succeeded. Fetch return values. */
+		iorequest.piod_op = PIOD_READ_D;
+		iorequest.piod_offs = (void *)regs.x[2];
+		iorequest.piod_addr = retval;
+		iorequest.piod_len = sizeof(retval[0]) * 2;
+		if (ptrace(PT_IO, tid, (caddr_t)&iorequest, 0) == -1 ||
+		    iorequest.piod_len == 0)
+			return (-1);
+		*errorp = 0;
+	} else {
+		/* System call failed. Set error. */
+		retval[0] = regs.x[0];
+		*errorp = 1;
+	}
+	return (0);
+}
+
+static struct procabi aarch64_cloudabi32 = {
+	"CloudABI ELF32",
+	SYSDECODE_ABI_CLOUDABI32,
+	aarch64_cloudabi32_fetch_args,
+	aarch64_cloudabi32_fetch_retval,
+	STAILQ_HEAD_INITIALIZER(aarch64_cloudabi32.extra_syscalls),
+	{ NULL }
+};
+
+PROCABI(aarch64_cloudabi32);