This patch prints the stack trace of the traced process after
each system call when using -k flag. It uses libunwind to
unwind the stack and to obtain the function name pointed by
the IP.
Tested on Ubuntu 12.04 64 with the distribution version of
libunwind (0.99-0.3ubuntu1) and on CentOS 6.3 with libunwind
form the source code. On Ubuntu you need the libunwind and
libunwind-dev package to compile the stack trace feature in
the code.
Some of this code was originally taken from strace-plus of
Philip J. Guo.
v2:
fixed several identation issues
removed a strlen in alloc_mmap_cache (Denys)
reload mmap_cache after execv
fixed a bug in libunwind_backtrace binary search (Masatake)
check return value of _UPT_create
use die_out_of_memory after Xalloc
use exiting instead of !entering
created a new separate unwind.c file
removed include from defs.h
added --with-libunwind to autoconf script
cleaned up defs.h from several inclusions
---
Makefile.am | 10 +++++++++-
configure.ac | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
defs.h | 45 +++++++++++++++++++++++++++++++++++++++++++++
mem.c | 7 +++++++
process.c | 8 ++++++++
strace.c | 43 +++++++++++++++++++++++++++++++++++++++++++
syscall.c | 9 +++++++++
7 files changed, 178 insertions(+), 1 deletion(-)
diff --git a/Makefile.am b/Makefile.am
index 9d611f3..c8ad026 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -12,7 +12,7 @@ ARCH = @arch@
ACLOCAL_AMFLAGS = -I m4
AM_CFLAGS = $(WARN_CFLAGS)
-AM_CPPFLAGS = -I$(srcdir)/$(OS)/$(ARCH) -I$(srcdir)/$(OS) -I$(builddir)/$(OS)
+AM_CPPFLAGS = -I$(srcdir)/$(OS)/$(ARCH) -I$(srcdir)/$(OS) -I$(builddir)/$(OS)
$(libunwind_CPPFLAGS)
strace_SOURCES = \
bjm.c \
@@ -43,6 +43,14 @@ strace_SOURCES = \
util.c \
vsprintf.c
+
+if LIB_UNWIND
+strace_SOURCES += unwind.c
+strace_LDADD = $(libunwind_LIBS)
+AM_LDFLAGS = $(libunwind_LDFLAGS)
+endif
+
+
noinst_HEADERS = defs.h
# Enable this to get link map generated
#strace_CFLAGS = $(AM_CFLAGS) -Wl,-Map=strace.mapfile
diff --git a/configure.ac b/configure.ac
index 03e49fe..526fbda 100644
--- a/configure.ac
+++ b/configure.ac
@@ -261,6 +261,63 @@ AC_CHECK_MEMBERS([struct sigcontext.sc_hi2],,, [#include
<signal.h>
# include <asm/sigcontext.h>
#endif])
+
+dnl stack trace with libunwind
+AC_ARG_WITH([libunwind],
+ [AS_HELP_STRING([--with-libunwind],
+ [libunwind is used to display system call
stacktrace])],
+ [case "${withval}" in
+ (yes|no) enable_libunwind=$withval;;
+ (*) enable_libunwind=yes
+ libunwind_CPPFLAGS="${AM_CPPFLAGS} -I${withval}/include"
+ libunwind_LDFLAGS="-L${withval}/lib" ;;
+ esac],
+ [enable_libunwind=maybe])
+
+AS_IF([test "x$enable_libunwind" != xno],
+ [saved_CPPFLAGS="${CPPFLAGS}"
+ CPPFLAGS="${CPPFLAGS} ${libunwind_CPPFLAGS}"
+ AC_CHECK_HEADERS([libunwind-ptrace.h libunwind.h])
+ CPPFLAGS="${saved_CPPFLAGS}" ])
+
+if test "x$ac_cv_header_libunwind_ptrace_h" = "xyes" &&
+ test "x$ac_cv_header_libunwind_h" = "xyes"; then
+
+ dnl code is taken from ltrace
+ case "${host_cpu}" in
+ arm*|sa110) UNWIND_ARCH="arm" ;;
+ i?86) UNWIND_ARCH="x86" ;;
+ powerpc) UNWIND_ARCH="ppc32" ;;
+ powerpc64) UNWIND_ARCH="ppc64" ;;
+ mips*) UNWIND_ARCH="mips" ;;
+ *) UNWIND_ARCH="${host_cpu}" ;;
+ esac
+
+ saved_LDFLAGS="${LDFLAGS}"
+ LDFLAGS="${LDFLAGS} ${libunwind_LDFLAGS}"
+ AC_CHECK_LIB([unwind], [backtrace],
+ [libunwind_LIBS="-lunwind"],
+ [AC_MSG_FAILURE([Unable to find libunwind])])
+ AC_CHECK_LIB([unwind-generic], [_U${UNWIND_ARCH}_create_addr_space],
+ [libunwind_LIBS="-lunwind-generic $libunwind_LIBS"],
+ [AC_MSG_FAILURE([Unable to find libunwind-generic])],
+ [$libunwind_LIBS])
+ AC_CHECK_LIB([unwind-ptrace], [_UPT_create],
+ [libunwind_LIBS="-lunwind-ptrace $libunwind_LIBS"],
+ [AC_MSG_FAILURE([Unable to find libunwind-ptrace])],
+ [$libunwind_LIBS])
+ LDFLAGS="${saved_LDFLAGS}"
+
+ dnl we have all the dependencies we need we can activate stack tracing
+ AC_SUBST(libunwind_LIBS)
+ AC_SUBST(libunwind_LDFLAGS)
+ AC_SUBST(libunwind_CPPFLAGS)
+ AC_DEFINE([LIB_UNWIND], 1, [Compile stack tracing functionality])
+ AC_MSG_NOTICE([Enabled stack tracing])
+fi
+AM_CONDITIONAL([LIB_UNWIND], [test "x$ac_cv_lib_unwind_ptrace__UPT_create" ==
"xyes"])
+
+
AC_CHECK_MEMBERS([struct utsname.domainname],,, [#include <sys/utsname.h>])
AC_CHECK_DECLS([sys_errlist])
diff --git a/defs.h b/defs.h
index 64cfc8d..b314622 100644
--- a/defs.h
+++ b/defs.h
@@ -405,6 +405,33 @@ typedef struct ioctlent {
unsigned long code;
} struct_ioctlent;
+
+#ifdef LIB_UNWIND
+
+/* keep a sorted array of cache entries, so that we can binary search
+ * through it
+ */
+struct mmap_cache_t {
+ /**
+ * example entry:
+ * 7fabbb09b000-7fabbb09f000 r--p 00179000 fc:00 1180246
/lib/libc-2.11.1.so
+ *
+ * start_addr is 0x7fabbb09b000
+ * end_addr is 0x7fabbb09f000
+ * mmap_offset is 0x179000
+ * binary_filename is "/lib/libc-2.11.1.so"
+ */
+ unsigned long start_addr;
+ unsigned long end_addr;
+ unsigned long mmap_offset;
+ char* binary_filename;
+};
+
+
+/* if this is true do the stack trace for every system call */
+extern bool use_libunwind;
+#endif
+
/* Trace Control Block */
struct tcb {
int flags; /* See below for TCB_ values */
@@ -430,6 +457,12 @@ struct tcb {
struct timeval etime; /* Syscall entry time */
/* Support for tracing forked processes: */
long inst[2]; /* Saved clone args (badly named) */
+
+#ifdef LIB_UNWIND
+ struct mmap_cache_t* mmap_cache;
+ int mmap_cache_size;
+ struct UPT_info* libunwind_ui;
+#endif
};
/* TCB flags */
@@ -721,6 +754,18 @@ extern void tv_sub(struct timeval *, struct timeval *,
struct timeval *);
extern void tv_mul(struct timeval *, struct timeval *, int);
extern void tv_div(struct timeval *, struct timeval *, int);
+#ifdef LIB_UNWIND
+/**
+ * print stack (-k flag) memory allocation and deallocation
+ */
+extern void alloc_mmap_cache(struct tcb* tcp);
+extern void delete_mmap_cache(struct tcb* tcp);
+extern void print_stacktrace(struct tcb* tcp);
+#else
+# define alloc_mmap_cache(tcp) ((void)0)
+# define delete_mmap_cache(tcp) ((void)0)
+#endif
+
/* Strace log generation machinery.
*
* printing_tcp: tcb which has incomplete line being printed right now.
diff --git a/mem.c b/mem.c
index ef273c7..a82b747 100644
--- a/mem.c
+++ b/mem.c
@@ -175,6 +175,9 @@ static int
print_mmap(struct tcb *tcp, long *u_arg, unsigned long long offset)
{
if (entering(tcp)) {
+ if (use_libunwind)
+ delete_mmap_cache(tcp);
+
/* addr */
if (!u_arg[0])
tprints("NULL, ");
@@ -304,6 +307,8 @@ sys_munmap(struct tcb *tcp)
tprintf("%#lx, %lu",
tcp->u_arg[0], tcp->u_arg[1]);
}
+ if (exiting(tcp) && use_libunwind)
+ delete_mmap_cache(tcp);
return 0;
}
@@ -315,6 +320,8 @@ sys_mprotect(struct tcb *tcp)
tcp->u_arg[0], tcp->u_arg[1]);
printflags(mmap_prot, tcp->u_arg[2], "PROT_???");
}
+ if (exiting(tcp) && use_libunwind)
+ delete_mmap_cache(tcp);
return 0;
}
diff --git a/process.c b/process.c
index e2fa25b..306aa23 100644
--- a/process.c
+++ b/process.c
@@ -992,6 +992,10 @@ sys_execve(struct tcb *tcp)
tprints("]");
}
}
+
+ if (exiting(tcp) && use_libunwind)
+ delete_mmap_cache(tcp);
+
return 0;
}
@@ -1209,6 +1213,10 @@ sys_waitid(struct tcb *tcp)
printrusage(tcp, tcp->u_arg[4]);
}
}
+
+ if (exiting(tcp) && use_libunwind)
+ delete_mmap_cache(tcp);
+
return 0;
}
diff --git a/strace.c b/strace.c
index a489db4..5956da6 100644
--- a/strace.c
+++ b/strace.c
@@ -50,6 +50,13 @@ extern char **environ;
extern int optind;
extern char *optarg;
+#ifdef LIB_UNWIND
+# include <libunwind-ptrace.h>
+
+/* if this is true do the stack trace for every system call */
+bool use_libunwind = false;
+unw_addr_space_t libunwind_as;
+#endif
#if defined __NR_tkill
# define my_tkill(tid, sig) syscall(__NR_tkill, (tid), (sig))
@@ -231,6 +238,10 @@ usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\
-E var -- remove var from the environment for command\n\
-P path -- trace accesses to path\n\
"
+#ifdef LIB_UNWIND
+"-k obtain stack trace between each syscall\n\
+"
+#endif
/* ancient, no one should use it
-F -- attempt to follow vforks (deprecated, use -f)\n\
*/
@@ -685,6 +696,15 @@ alloctcb(int pid)
#if SUPPORTED_PERSONALITIES > 1
tcp->currpers = current_personality;
#endif
+
+#ifdef LIB_UNWIND
+ if (use_libunwind) {
+ tcp->libunwind_ui = _UPT_create(tcp->pid);
+ if (!tcp->libunwind_ui)
+ die_out_of_memory();
+ }
+#endif
+
nprocs++;
if (debug_flag)
fprintf(stderr, "new tcb for pid %d, active
tcbs:%d\n", tcp->pid, nprocs);
@@ -721,6 +741,12 @@ droptcb(struct tcb *tcp)
if (printing_tcp == tcp)
printing_tcp = NULL;
+#ifdef LIB_UNWIND
+ if (use_libunwind) {
+ delete_mmap_cache(tcp);
+ _UPT_destroy(tcp->libunwind_ui);
+ }
+#endif
memset(tcp, 0, sizeof(*tcp));
}
@@ -1642,6 +1668,9 @@ init(int argc, char *argv[])
qualify("signal=all");
while ((c = getopt(argc, argv,
"+b:cCdfFhiqrtTvVxyz"
+#ifdef LIB_UNWIND
+ "k"
+#endif
"D"
"a:e:o:O:p:s:S:u:E:P:I:")) != EOF) {
switch (c) {
@@ -1744,6 +1773,11 @@ init(int argc, char *argv[])
case 'u':
username = strdup(optarg);
break;
+#ifdef LIB_UNWIND
+ case 'k':
+ use_libunwind = true;
+ break;
+#endif
case 'E':
if (putenv(optarg) < 0)
die_out_of_memory();
@@ -1775,6 +1809,15 @@ init(int argc, char *argv[])
error_msg_and_die("-D and -p are mutually exclusive");
}
+#ifdef LIB_UNWIND
+ if (use_libunwind) {
+ libunwind_as = unw_create_addr_space(&_UPT_accessors, 0);
+ if (!libunwind_as) {
+ error_msg_and_die("Fatal error: unable to create
address space for stack tracing\n");
+ }
+ }
+#endif
+
if (!followfork)
followfork = optF;
diff --git a/syscall.c b/syscall.c
index f524b13..dee4c61 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2684,6 +2684,15 @@ trace_syscall_exiting(struct tcb *tcp)
dumpio(tcp);
line_ended();
+#ifdef LIB_UNWIND
+ if (use_libunwind) {
+ if (!tcp->mmap_cache) {
+ alloc_mmap_cache(tcp);
+ }
+ print_stacktrace(tcp);
+ }
+#endif
+
ret:
tcp->flags &= ~TCB_INSYSCALL;
return 0;
--
1.7.9.5
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