* vm_dump.c (backtrace): use rip in the saved context for the case

  the SIGSEGV is received when the process is in userland.
  Note that ip in the stack should be used if the signal is received
  when it is in kernel (when it is calling syscall) [Bug #12711]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56030 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 0 deletions

diff --git a/vm_dump.c b/vm_dump.c
index c0f0685f0b..f8cde6d595 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -470,6 +470,9 @@ darwin_sigtramp:
 	unw_set_reg(&cursor, UNW_X86_64_R14, uctx->uc_mcontext->__ss.__r14);
 	unw_set_reg(&cursor, UNW_X86_64_R15, uctx->uc_mcontext->__ss.__r15);
 	ip = *(unw_word_t*)uctx->uc_mcontext->__ss.__rsp;
+	if (!ip) { /* signal received in syscall */
+	    ip = uctx->uc_mcontext->__ss.__rip;
+	}
 	unw_set_reg(&cursor, UNW_REG_IP, ip);
 	trace[n++] = (void *)uctx->uc_mcontext->__ss.__rip;
 	trace[n++] = (void *)ip;