[4/7] Step over fork/vfork syscall insn in gdbserver
Commit Message
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(+)
Comments
On 02/26/2016 11:03 AM, Yao Qi wrote:
> 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
"... interference with ..."
@@ -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 $syscall"
+ # Delete breakpoint syscall insns to avoid interference to other syscalls.
+ delete_breakpoints
+
+
+ # Create a breakpoint with a condition that evals false.
+ gdb_test "break \*$syscall_insn_addr if main == 0" \
+ "Breakpoint \[0-9\]* at .*"
+
+ gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
+ gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
+ "continue to marker ($syscall)"
+ }
+}
+
disp_step_cross_syscall "fork"
disp_step_cross_syscall "vfork"
+
+set testfile "disp-step-fork"
+clean_restart $testfile
+if { ![runto main] } then {
+ fail "run to main"
+ return -1
+}
+
+set cond_bp_target 1
+
+set test "set breakpoint condition-evaluation target"
+gdb_test_multiple $test $test {
+ -re "warning: Target does not support breakpoint condition evaluation.\r\nUsing host evaluation mode instead.\r\n$gdb_prompt $" {
+ # Target doesn't support breakpoint condition
+ # evaluation on its side.
+ set cond_bp_target 0
+ }
+ -re "^$test\r\n$gdb_prompt $" {
+ }
+}
+
+if { $cond_bp_target } {
+ break_cond_on_syscall "fork"
+ break_cond_on_syscall "vfork"
+}