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| author | Stefan Liebler <stli@linux.vnet.ibm.com> | 2015-07-07 16:11:14 +0200 |
|---|---|---|
| committer | Andreas Krebbel <krebbel@linux.vnet.ibm.com> | 2015-07-07 16:11:14 +0200 |
| commit | 890b7a4b33d482b5c768ab47d70758b80227e9bc (patch) | |
| tree | d1c0d9f0005382a0b051f227f5a0ea9af89f89b3 /sysdeps/unix/sysv/linux/s390/s390-32 | |
| parent | fa4eeac73dd1c368bf06ef071fdf20d9f40c6c15 (diff) | |
| download | glibc-890b7a4b33d482b5c768ab47d70758b80227e9bc.tar.gz glibc-890b7a4b33d482b5c768ab47d70758b80227e9bc.tar.xz glibc-890b7a4b33d482b5c768ab47d70758b80227e9bc.zip | |
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 'sysdeps/unix/sysv/linux/s390/s390-32')
| -rw-r--r-- | sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S b/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S index e1f9347f42..ad39bb8433 100644 --- a/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S +++ b/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S @@ -17,6 +17,14 @@ #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. */ |