merge revision(s) 56030,56035: [Backport #12711]

	* 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/branches/ruby_2_2@56308 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 7 insertions, 3 deletions

diff --git a/vm_dump.c b/vm_dump.c
index b33936de96..155bb62d09 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -487,10 +487,14 @@ darwin_sigtramp:
 	unw_set_reg(&cursor, UNW_X86_64_R13, uctx->uc_mcontext->__ss.__r13);
 	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;
-	unw_set_reg(&cursor, UNW_REG_IP, ip);
-	trace[n++] = (void *)uctx->uc_mcontext->__ss.__rip;
+	ip = uctx->uc_mcontext->__ss.__rip;
+	if (((char*)ip)[-2] == 0x0f && ((char*)ip)[-1] == 5) {
+	    /* signal received in syscall */
+	    trace[n++] = (void *)ip;
+	    ip = *(unw_word_t*)uctx->uc_mcontext->__ss.__rsp;
+	}
 	trace[n++] = (void *)ip;
+	unw_set_reg(&cursor, UNW_REG_IP, ip);
     }
     while (unw_step(&cursor) > 0) {
 	unw_get_reg(&cursor, UNW_REG_IP, &ip);