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commit 890b7a4b33d482b5c768ab47d70758b80227e9bc
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Author: Stefan Liebler <stli@linux.vnet.ibm.com>
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Date: Tue Jul 7 16:11:14 2015 +0200
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S390: Fix "backtrace() returns infinitely deep stack frames with makecontext()" [BZ #18508].
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diff --git a/stdlib/Makefile b/stdlib/Makefile
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index 8f22c8d..c1e80d7 100644
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--- a/stdlib/Makefile
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+++ b/stdlib/Makefile
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@@ -154,3 +154,4 @@ $(objpfx)bug-getcontext: $(link-libm)
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$(objpfx)tst-strtod-round: $(link-libm)
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$(objpfx)tst-tininess: $(link-libm)
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$(objpfx)tst-strtod-underflow: $(link-libm)
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+$(objpfx)tst-makecontext: $(libdl)
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diff --git a/stdlib/tst-makecontext.c b/stdlib/tst-makecontext.c
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index eb6e89b..1420857 100644
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--- a/stdlib/tst-makecontext.c
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+++ b/stdlib/tst-makecontext.c
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@@ -19,23 +19,62 @@
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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[8192];
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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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+
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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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+
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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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+
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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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+
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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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diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S b/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
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index ab172bb..365c2b0 100644
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--- a/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
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+++ b/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
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@@ -17,6 +17,14 @@
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#include <sysdep.h>
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+/* We do not want .eh_frame info so that __makecontext_ret stops unwinding
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+ if backtrace was called within a context created by makecontext. (There
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+ is also no .eh_frame info for _start or thread_start.) */
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+#undef cfi_startproc
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+#define cfi_startproc
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+#undef cfi_endproc
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+#define cfi_endproc
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+
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ENTRY(__makecontext_ret)
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basr %r14,%r7
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ltr %r8,%r8 /* Check whether uc_link is 0. */
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diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S b/sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S
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index cbd88e1..c4a43bd 100644
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--- a/sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S
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+++ b/sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S
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@@ -17,6 +17,14 @@
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#include <sysdep.h>
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+/* We do not want .eh_frame info so that __makecontext_ret stops unwinding
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+ if backtrace was called within a context created by makecontext. (There
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+ is also no .eh_frame info for _start or thread_start.) */
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+#undef cfi_startproc
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+#define cfi_startproc
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+#undef cfi_endproc
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+#define cfi_endproc
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+
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ENTRY(__makecontext_ret)
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basr %r14,%r7
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ltgr %r8,%r8 /* Check whether uc_link is 0. */
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