On s390/s390x backtrace(buffer, size) returns the series of called functions until
"makecontext_ret" and additional entries (up to "size") with "makecontext_ret".
GDB-backtrace is also warning:
"Backtrace stopped: previous frame identical to this frame (corrupt stack?)"
To reproduce this scenario you have to setup a new context with makecontext()
and activate it with setcontext(). See e.g. cf() function in testcase stdlib/tst-makecontext.c.
Or see bug in libgo "Bug 66303 - runtime.Caller() returns infinitely deep stack frames
on s390x " (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66303).
This patch omits the cfi_startproc/cfi_endproc directives in ENTRY/END macro of
__makecontext_ret. Thus no frame information is generated in .eh_frame and backtrace
stops after __makecontext_ret. There is also no .eh_frame info for _start or
thread_start functions.
ChangeLog:
[BZ #18508]
* stdlib/Makefile ($(objpfx)tst-makecontext3):
Depend on $(libdl).
* stdlib/tst-makecontext.c (cf): Test if _Unwind_Backtrace
is not called infinitely times.
(backtrace_helper): New function.
(trace_arg): New struct.
(st1): Enlarge stack size.
* sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S:
(__makecontext_ret): Omit cfi_startproc and cfi_endproc.
* sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S:
Likewise.
(cherry picked from commit
890b7a4b33d482b5c768ab47d70758b80227e9bc)
+2016-04-28 Stefan Liebler <stli@linux.vnet.ibm.com>
+
+ [BZ #18508]
+ * stdlib/Makefile ($(objpfx)tst-makecontext3):
+ Depend on $(libdl).
+ * stdlib/tst-makecontext.c (cf): Test if _Unwind_Backtrace
+ is not called infinitely times.
+ (backtrace_helper): New function.
+ (trace_arg): New struct.
+ (st1): Enlarge stack size.
+ * sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S:
+ (__makecontext_ret): Omit cfi_startproc and cfi_endproc.
+ * sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S:
+ Likewise.
+
2016-04-28 Stefan Liebler <stli@linux.vnet.ibm.com>
[BZ #18080]
* The following bugs are resolved with this release:
16009, 16617, 16618, 17266, 17269, 17370, 17371, 17460, 17485, 17555,
- 17625, 17630, 17801, 18032, 18080, 18665, 18694, 18928, 19018, 19682.
+ 17625, 17630, 17801, 18032, 18080, 18508, 18665, 18694, 18928, 19018,
+ 19682.
* A stack-based buffer overflow was found in libresolv when invoked from
libnss_dns, allowing specially crafted DNS responses to seize control
$(objpfx)tst-tls-atexit: $(shared-thread-library) $(libdl)
$(objpfx)tst-tls-atexit.out: $(objpfx)tst-tls-atexit-lib.so
+
+$(objpfx)tst-makecontext: $(libdl)
#include <stdlib.h>
#include <stdio.h>
#include <ucontext.h>
+#include <assert.h>
+#include <unwind.h>
+#include <dlfcn.h>
+#include <gnu/lib-names.h>
ucontext_t ucp;
-char st1[8192];
+char st1[16384];
__thread int thr;
int somevar = -76;
long othervar = -78L;
+struct trace_arg
+{
+ int cnt, size;
+};
+
+static _Unwind_Reason_Code
+backtrace_helper (struct _Unwind_Context *ctx, void *a)
+{
+ struct trace_arg *arg = a;
+ if (++arg->cnt == arg->size)
+ return _URC_END_OF_STACK;
+ return _URC_NO_REASON;
+}
+
void
cf (int i)
{
+ struct trace_arg arg = { .size = 100, .cnt = -1 };
+ void *handle;
+ _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
+
if (i != othervar || thr != 94)
{
printf ("i %d thr %d\n", i, thr);
exit (1);
}
+ /* Test if callback function of _Unwind_Backtrace is not called infinitely
+ times. See Bug 18508 or gcc bug "Bug 66303 - runtime.Caller() returns
+ infinitely deep stack frames on s390x.".
+ The go runtime calls backtrace_full() in
+ <gcc-src>/libbacktrace/backtrace.c, which uses _Unwind_Backtrace(). */
+ handle = dlopen (LIBGCC_S_SO, RTLD_LAZY);
+ if (handle != NULL)
+ {
+ unwind_backtrace = dlsym (handle, "_Unwind_Backtrace");
+ if (unwind_backtrace != NULL)
+ {
+ unwind_backtrace (backtrace_helper, &arg);
+ assert (arg.cnt != -1 && arg.cnt < 100);
+ }
+ dlclose (handle);
+ }
+
/* Since uc_link below has been set to NULL, setcontext is supposed to
terminate the process normally after this function returns. */
}
#include <sysdep.h>
+/* We do not want .eh_frame info so that __makecontext_ret stops unwinding
+ if backtrace was called within a context created by makecontext. (There
+ is also no .eh_frame info for _start or thread_start.) */
+#undef cfi_startproc
+#define cfi_startproc
+#undef cfi_endproc
+#define cfi_endproc
+
ENTRY(__makecontext_ret)
basr %r14,%r7
ltr %r8,%r8 /* Check whether uc_link is 0. */
#include <sysdep.h>
+/* We do not want .eh_frame info so that __makecontext_ret stops unwinding
+ if backtrace was called within a context created by makecontext. (There
+ is also no .eh_frame info for _start or thread_start.) */
+#undef cfi_startproc
+#define cfi_startproc
+#undef cfi_endproc
+#define cfi_endproc
+
ENTRY(__makecontext_ret)
basr %r14,%r7
ltgr %r8,%r8 /* Check whether uc_link is 0. */
projects / thirdparty / glibc.git / commitdiff
