From 68e9b1e8e1dc4b508a2c7f7f87a9b21723172aeb Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Fri, 12 Aug 2016 07:54:59 +0000
Subject: [PATCH] Decode 32bit utrace records on the 64bit host.

Suppose that ktrace is performed on 32bit binary running on 64bit
host.  In this case, the kernel records are 64bit, while utrace
records from rtld and malloc are 32bit.  Make kdump useful to see
decoded utrace data in that case.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
---
 lib/libsysdecode/utrace.c | 56 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 54 insertions(+), 2 deletions(-)

diff --git a/lib/libsysdecode/utrace.c b/lib/libsysdecode/utrace.c
index 6a251390b2b..28e52c3fe4d 100644
--- a/lib/libsysdecode/utrace.c
+++ b/lib/libsysdecode/utrace.c
@@ -33,7 +33,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <dlfcn.h>
 #include <stdio.h>
-#include <strings.h>
+#include <string.h>
 #include <sysdecode.h>
 
 #define	UTRACE_DLOPEN_START		1
@@ -59,6 +59,18 @@ struct utrace_rtld {
 	char name[MAXPATHLEN];
 };
 
+#ifdef __LP64__
+struct utrace_rtld32 {
+	char sig[4];				/* 'RTLD' */
+	int event;
+	uint32_t handle;
+	uint32_t mapbase;
+	uint32_t mapsize;
+	int refcnt;
+	char name[MAXPATHLEN];
+};
+#endif
+
 static int
 print_utrace_rtld(FILE *fp, void *p)
 {
@@ -145,6 +157,14 @@ struct utrace_malloc {
 	void *r;
 };
 
+#ifdef __LP64__
+struct utrace_malloc32 {
+	uint32_t p;
+	uint32_t s;
+	uint32_t r;
+};
+#endif
+
 static void
 print_utrace_malloc(FILE *fp, void *p)
 {
@@ -163,6 +183,12 @@ print_utrace_malloc(FILE *fp, void *p)
 int
 sysdecode_utrace(FILE *fp, void *p, size_t len)
 {
+#ifdef __LP64__
+	struct utrace_rtld ur;
+	struct utrace_rtld32 *pr;
+	struct utrace_malloc um;
+	struct utrace_malloc32 *pm;
+#endif
 
 	if (len == sizeof(struct utrace_rtld) && bcmp(p, "RTLD", 4) == 0) {
 		return (print_utrace_rtld(fp, p));
@@ -172,6 +198,32 @@ sysdecode_utrace(FILE *fp, void *p, size_t len)
 		print_utrace_malloc(fp, p);
 		return (1);
 	}
-	
+
+#ifdef __LP64__
+	if (len == sizeof(struct utrace_rtld32) && bcmp(p, "RTLD", 4) == 0) {
+		pr = p;
+		memset(&ur, 0, sizeof(ur));
+		memcpy(ur.sig, pr->sig, sizeof(ur.sig));
+		ur.event = pr->event;
+		ur.handle = (void *)(uintptr_t)pr->handle;
+		ur.mapbase = (void *)(uintptr_t)pr->mapbase;
+		ur.mapsize = pr->mapsize;
+		ur.refcnt = pr->refcnt;
+		memcpy(ur.name, pr->name, sizeof(ur.name));
+		return (print_utrace_rtld(fp, &ur));
+	}
+
+	if (len == sizeof(struct utrace_malloc32)) {
+		pm = p;
+		memset(&um, 0, sizeof(um));
+		um.p = pm->p == (uint32_t)-1 ? (void *)(intptr_t)-1 :
+		    (void *)(uintptr_t)pm->p;
+		um.s = pm->s;
+		um.r = (void *)(uintptr_t)pm->r;
+		print_utrace_malloc(fp, &um);
+		return (1);
+	}
+#endif
+
 	return (0);
 }