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authorStefan Liebler <stli@linux.vnet.ibm.com>2015-07-07 16:11:14 +0200
committerAndreas Krebbel <krebbel@linux.vnet.ibm.com>2015-07-07 16:11:14 +0200
commit890b7a4b33d482b5c768ab47d70758b80227e9bc (patch)
treed1c0d9f0005382a0b051f227f5a0ea9af89f89b3 /stdlib
parentfa4eeac73dd1c368bf06ef071fdf20d9f40c6c15 (diff)
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S390: Fix "backtrace() returns infinitely deep stack frames with makecontext()" [BZ #18508].
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.
Diffstat (limited to 'stdlib')
-rw-r--r--stdlib/Makefile2
-rw-r--r--stdlib/tst-makecontext.c41
2 files changed, 42 insertions, 1 deletions
diff --git a/stdlib/Makefile b/stdlib/Makefile
index 3300dd2142..7fc5a807fa 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -164,3 +164,5 @@ $(objpfx)tst-setcontext3.out: tst-setcontext3.sh $(objpfx)tst-setcontext3
'$(run-program-env)' '$(test-program-prefix-after-env)' \
$(common-objpfx)stdlib/; \
$(evaluate-test)
+
+$(objpfx)tst-makecontext: $(libdl)
diff --git a/stdlib/tst-makecontext.c b/stdlib/tst-makecontext.c
index 29a588e588..8170e8aeed 100644
--- a/stdlib/tst-makecontext.c
+++ b/stdlib/tst-makecontext.c
@@ -19,23 +19,62 @@
#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. */
}