From 4be29fb3c55b8b352e7d02ff93df793b2133dffe Mon Sep 17 00:00:00 2001
From: Ed Schouten <ed@FreeBSD.org>
Date: Thu, 21 Dec 2017 09:21:40 +0000
Subject: [PATCH] Make truss work for CloudABI executables on i386.

The system call convention is different from i386 binaries running on
FreeBSD/amd64, but this is not noticeable by executables. On
FreeBSD/amd64, the vDSO already does padding of arguments and return
values to 64-bit values. On i386, it does not, meaning that system call
return values are simply stored in registers.
---
 usr.bin/truss/Makefile          |  1 +
 usr.bin/truss/i386-cloudabi32.c | 98 +++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)
 create mode 100644 usr.bin/truss/i386-cloudabi32.c

diff --git a/usr.bin/truss/Makefile b/usr.bin/truss/Makefile
index ad4f0f5ac30b..7eddb012a643 100644
--- a/usr.bin/truss/Makefile
+++ b/usr.bin/truss/Makefile
@@ -18,6 +18,7 @@ ABIS+=		cloudabi64
 .endif
 .if ${MACHINE_CPUARCH} == "i386"
 ABIS+=		i386-linux
+ABIS+=		cloudabi32
 .endif
 .if ${MACHINE_CPUARCH} == "amd64"
 ABIS+=		amd64-linux
diff --git a/usr.bin/truss/i386-cloudabi32.c b/usr.bin/truss/i386-cloudabi32.c
new file mode 100644
index 000000000000..2d8c1128ec2b
--- /dev/null
+++ b/usr.bin/truss/i386-cloudabi32.c
@@ -0,0 +1,98 @@
+/*-
+ * Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/ptrace.h>
+
+#include <machine/psl.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <sysdecode.h>
+
+#include "truss.h"
+
+static int
+i386_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 stack pointer. */
+		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. */
+		cs = &trussinfo->curthread->cs;
+		iorequest.piod_op = PIOD_READ_D;
+		iorequest.piod_offs = (void **)regs.r_esp + 1;
+		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
+i386_cloudabi32_fetch_retval(struct trussinfo *trussinfo, long *retval,
+    int *errorp)
+{
+	struct reg regs;
+	lwpid_t tid;
+
+	tid = trussinfo->curthread->tid;
+	if (ptrace(PT_GETREGS, tid, (caddr_t)&regs, 0) == -1) {
+		fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
+		return (-1);
+	}
+
+	retval[0] = regs.r_eax;
+	retval[1] = regs.r_edx;
+	*errorp = (regs.r_eflags & PSL_C) != 0;
+	return (0);
+}
+
+static struct procabi i386_cloudabi32 = {
+	"CloudABI ELF32",
+	SYSDECODE_ABI_CLOUDABI32,
+	i386_cloudabi32_fetch_args,
+	i386_cloudabi32_fetch_retval,
+	STAILQ_HEAD_INITIALIZER(i386_cloudabi32.extra_syscalls),
+	{ NULL }
+};
+
+PROCABI(i386_cloudabi32);