We can also extend disp-step-syscall.exp to test GDBserver step over
breakpoint on syscall instruction. That is, we set a breakpoint
with a false condition on syscall instruction, so that GDBserver will
step over it.
This test triggers a GDBserver internal error, which can be fixed by
this series.
(gdb) PASS: gdb.base/disp-step-syscall.exp: fork: break cond on target: break on syscall insns
continue^M
Continuing.^M
Remote connection closed^M
(gdb) FAIL: gdb.base/disp-step-syscall.exp: fork: break cond on target: continue to fork again
In GDBserver, there is an internal error,
/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/linux-low.c:1922: A problem internal to GDBserver has been detected.
unsuspend LWP 25554, suspended=-1
the simplified reproducer is like,
$ ./gdb ./testsuite/outputs/gdb.base/disp-step-syscall/disp-step-fork
(gdb) b main
(gdb) c
(gdb) disassemble fork // in order to find the address of insn 'syscall'
....
0x00007ffff7ad6023 <+179>: syscall
(gdb) b *0x00007ffff7ad6023 if main == 0
(gdb) c
gdb/testsuite:
2016-02-26 Yao Qi <yao.qi@linaro.org>
* gdb.base/disp-step-syscall.exp (break_cond_on_syscall): New.
If target supports condition evaluation on target, invoke
break_cond_on_syscall for fork and vfork.
---
gdb/testsuite/gdb.base/disp-step-syscall.exp | 57 ++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/gdb/testsuite/gdb.base/disp-step-syscall.exp b/gdb/testsuite/gdb.base/disp-step-syscall.exp
index 3cf436d..9ecf2a5 100644
--- a/gdb/testsuite/gdb.base/disp-step-syscall.exp
+++ b/gdb/testsuite/gdb.base/disp-step-syscall.exp
@@ -168,5 +168,62 @@ proc disp_step_cross_syscall { syscall } {
}
}
+# Set a breakpoint with a condition that evals false on syscall
+# instruction. In fact, it tests GDBserver steps over syscall
+# instruction.
+
+proc break_cond_on_syscall { syscall } {
+ with_test_prefix "break cond on target : $syscall" {
+ set testfile "disp-step-$syscall"
+
+ set ret [setup $syscall]
+
+ set syscall_insn_addr [lindex $ret 0]
+ set syscall_insn_next_addr [lindex $ret 1]
+ if { $syscall_insn_addr == -1 } {
+ return -1
+ }
+
+ gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
+ "continue to $syscall"
+ # Delete breakpoint syscall insns to avoid interference to other syscalls.
+ delete_breakpoints