[IA64] enable singlestep on system call
As is pointed out in
http://www.gelato.org/community/view_linear.php?id=1_1036&from=authors&value=Ian%20Wienand#1_1039,
if single step on break instruction, the break fault has higher
priority than the single-step trap. When the break fault handler
is entered, it advances the IP by 1 instruction so break instruction
single-stepping is skipped, actually it is next instruction which
is single stepped.
This patch modifies this, it adds TIF_SINGLESTEP bit for thread
flags, and generate a fake sigtrap when single stepping break
instruction. Test case in attachment can verify this. Any comments
is welcome.
Signed-off-by: bibo, mao <bibo.mao@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index aa705e4..f1ec129 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -1405,6 +1405,7 @@
struct ia64_psr *child_psr = ia64_psr(task_pt_regs(child));
/* make sure the single step/taken-branch trap bits are not set: */
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
child_psr->ss = 0;
child_psr->tb = 0;
}
@@ -1525,6 +1526,7 @@
* Make sure the single step/taken-branch trap bits
* are not set:
*/
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
ia64_psr(pt)->ss = 0;
ia64_psr(pt)->tb = 0;
@@ -1556,6 +1558,7 @@
goto out_tsk;
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ set_tsk_thread_flag(child, TIF_SINGLESTEP);
if (request == PTRACE_SINGLESTEP) {
ia64_psr(pt)->ss = 1;
} else {
@@ -1595,13 +1598,9 @@
}
-void
+static void
syscall_trace (void)
{
- if (!test_thread_flag(TIF_SYSCALL_TRACE))
- return;
- if (!(current->ptrace & PT_PTRACED))
- return;
/*
* The 0x80 provides a way for the tracing parent to
* distinguish between a syscall stop and SIGTRAP delivery.
@@ -1664,7 +1663,8 @@
audit_syscall_exit(success, result);
}
- if (test_thread_flag(TIF_SYSCALL_TRACE)
+ if ((test_thread_flag(TIF_SYSCALL_TRACE)
+ || test_thread_flag(TIF_SINGLESTEP))
&& (current->ptrace & PT_PTRACED))
syscall_trace();
}