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Commit 90f9d70a authored by bibo,mao's avatar bibo,mao Committed by Tony Luck
Browse files

[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: default avatarbibo, mao <bibo.mao@intel.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent c237508a

arch/ia64/kernel/ptrace.c

+6 −6
Original line number Diff line number Diff line
@@ -1405,6 +1405,7 @@ ptrace_disable (struct task_struct *child) 
	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 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data) 
		 * 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 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data) 
			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 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data) 
}





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 @@ syscall_trace_leave (long arg0, long arg1, long arg2, long arg3, 
		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();

}

include/asm-ia64/thread_info.h

+3 −1
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ struct thread_info { 
#define TIF_NEED_RESCHED	2	/* rescheduling necessary */

#define TIF_SYSCALL_TRACE	3	/* syscall trace active */

#define TIF_SYSCALL_AUDIT	4	/* syscall auditing active */

#define TIF_SINGLESTEP		5	/* restore singlestep on return to user mode */

#define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */

#define TIF_MEMDIE		17

#define TIF_MCA_INIT		18	/* this task is processing MCA or INIT */
@@ -92,7 +93,8 @@ struct thread_info { 


#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)

#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)

#define _TIF_SYSCALL_TRACEAUDIT	(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)

#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)

#define _TIF_SYSCALL_TRACEAUDIT	(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP)

#define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)

#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)

#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)