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[PATCH 5/8] Step over fork/vfork syscall insn in gdbserver
- From: Yao Qi <qiyaoltc at gmail dot com>
- To: gdb-patches at sourceware dot org
- Date: Fri, 19 Feb 2016 14:36:31 +0000
- Subject: [PATCH 5/8] Step over fork/vfork syscall insn in gdbserver
- Authentication-results: sourceware.org; auth=none
- References: <1455892594-2294-1-git-send-email-yao dot qi at linaro dot org>
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:
2016-02-19 Yao Qi <yao.qi@linaro.org>
* gdb.base/disp-step-fork.c (main): Increase loop boundary.
* gdb.base/disp-step-vfork.c (main): Likewise.
* gdb.base/disp-step-syscall.exp (disp_step_cross_syscall): Test
breakpoint condition evaluated on the target side.
---
gdb/testsuite/gdb.base/disp-step-fork.c | 2 +-
gdb/testsuite/gdb.base/disp-step-syscall.exp | 38 ++++++++++++++++++++++++++++
gdb/testsuite/gdb.base/disp-step-vfork.c | 2 +-
3 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/gdb/testsuite/gdb.base/disp-step-fork.c b/gdb/testsuite/gdb.base/disp-step-fork.c
index d8d602f..6d477ea 100644
--- a/gdb/testsuite/gdb.base/disp-step-fork.c
+++ b/gdb/testsuite/gdb.base/disp-step-fork.c
@@ -26,7 +26,7 @@ main (void)
{
int i, pid;
- for (i = 0; i < 4; i++)
+ for (i = 0; i < 6; i++)
{
pid = fork ();
if (pid == 0) /* child */
diff --git a/gdb/testsuite/gdb.base/disp-step-syscall.exp b/gdb/testsuite/gdb.base/disp-step-syscall.exp
index 9e43fbb..53ac1e1 100644
--- a/gdb/testsuite/gdb.base/disp-step-syscall.exp
+++ b/gdb/testsuite/gdb.base/disp-step-syscall.exp
@@ -153,6 +153,44 @@ proc disp_step_cross_syscall { syscall } {
}
}
+ with_test_prefix "break cond on target" {
+ 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 } {
+ gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
+ "continue to $syscall"
+
+ # Create a breakpoint with the condition which is false.
+ set syscall_insn_bp 0
+ gdb_test_multiple "break \*$syscall_insn_addr if main == 0" \
+ "break on syscall insns" {
+ -re "Breakpoint (\[0-9\]*) at .*$gdb_prompt $" {
+ set syscall_insn_bp $expect_out(1,string)
+ pass "break on syscall insns"
+ }
+ }
+
+ gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
+ "continue to $syscall again"
+
+ # Delete breakpoint syscall insns to avoid interference to
+ # other syscalls.
+ gdb_test_no_output "delete $syscall_insn_bp" \
+ "delete break $syscall insn"
+ }
+ }
+
gdb_test_no_output "delete $syscall_bp" "delete break $syscall"
gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
diff --git a/gdb/testsuite/gdb.base/disp-step-vfork.c b/gdb/testsuite/gdb.base/disp-step-vfork.c
index 17bef55..35665ab 100644
--- a/gdb/testsuite/gdb.base/disp-step-vfork.c
+++ b/gdb/testsuite/gdb.base/disp-step-vfork.c
@@ -25,7 +25,7 @@ main (void)
{
int i, pid;
- for (i = 0; i < 4; i++)
+ for (i = 0; i < 6; i++)
{
pid = vfork ();
if (pid == -1)
--
1.9.1