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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.
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
/* Copyright (C) 2006-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <ucontext.h>
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#include <assert.h>
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#include <unwind.h>
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#include <dlfcn.h>
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#include <gnu/lib-names.h>
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ucontext_t ucp;
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char st1[16384];
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__thread int thr;
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int somevar = -76;
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long othervar = -78L;
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struct trace_arg
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{
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int cnt, size;
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};
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static _Unwind_Reason_Code
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backtrace_helper (struct _Unwind_Context *ctx, void *a)
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{
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struct trace_arg *arg = a;
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if (++arg->cnt == arg->size)
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return _URC_END_OF_STACK;
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return _URC_NO_REASON;
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}
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void
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cf (int i)
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{
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struct trace_arg arg = { .size = 100, .cnt = -1 };
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void *handle;
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_Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
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if (i != othervar || thr != 94)
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{
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printf ("i %d thr %d\n", i, thr);
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exit (1);
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}
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/* Test if callback function of _Unwind_Backtrace is not called infinitely
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times. See Bug 18508 or gcc bug "Bug 66303 - runtime.Caller() returns
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infinitely deep stack frames on s390x.".
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The go runtime calls backtrace_full() in
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<gcc-src>/libbacktrace/backtrace.c, which uses _Unwind_Backtrace(). */
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handle = dlopen (LIBGCC_S_SO, RTLD_LAZY);
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if (handle != NULL)
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{
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unwind_backtrace = dlsym (handle, "_Unwind_Backtrace");
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if (unwind_backtrace != NULL)
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{
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unwind_backtrace (backtrace_helper, &arg);
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assert (arg.cnt != -1 && arg.cnt < 100);
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}
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dlclose (handle);
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}
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/* Since uc_link below has been set to NULL, setcontext is supposed to
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terminate the process normally after this function returns. */
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}
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int
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do_test (void)
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{
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if (getcontext (&ucp) != 0)
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{
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if (errno == ENOSYS)
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{
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puts ("context handling not supported");
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return 0;
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}
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puts ("getcontext failed");
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return 1;
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}
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thr = 94;
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ucp.uc_link = NULL;
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ucp.uc_stack.ss_sp = st1;
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ucp.uc_stack.ss_size = sizeof st1;
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makecontext (&ucp, (void (*) (void)) cf, 1, somevar - 2);
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if (setcontext (&ucp) != 0)
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{
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puts ("setcontext failed");
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return 1;
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}
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return 2;
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}
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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