Commit c200e4bb authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP 



User mode linux is the last user of the PT_DTRACE flag.  Using the flag to indicate
single stepping is a little confusing and worse changing tsk->ptrace without locking
could potentionally cause problems.

So use a thread info flag with a better name instead of flag in tsk->ptrace.

Remove the definition PT_DTRACE as uml is the last user.

Cc: stable@vger.kernel.org
Acked-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Tested-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-3-ebiederm@xmission.com


Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent e71ba124

arch/um/include/asm/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ static inline struct thread_info *current_thread_info(void) 
#define TIF_RESTORE_SIGMASK	7

#define TIF_NOTIFY_RESUME	8

#define TIF_SECCOMP		9	/* secure computing */

#define TIF_SINGLESTEP		10	/* single stepping userspace */



#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)

#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
@@ -68,5 +69,6 @@ static inline struct thread_info *current_thread_info(void) 
#define _TIF_MEMDIE		(1 << TIF_MEMDIE)

#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)

#define _TIF_SECCOMP		(1 << TIF_SECCOMP)

#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)



#endif

arch/um/kernel/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp) 
{

	PT_REGS_IP(regs) = eip;

	PT_REGS_SP(regs) = esp;

	current->ptrace &= ~PT_DTRACE;

	clear_thread_flag(TIF_SINGLESTEP);

#ifdef SUBARCH_EXECVE1

	SUBARCH_EXECVE1(regs->regs);

#endif

arch/um/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -335,7 +335,7 @@ int singlestepping(void * t) 
{

	struct task_struct *task = t ? t : current;



	if (!(task->ptrace & PT_DTRACE))

	if (!test_thread_flag(TIF_SINGLESTEP))

		return 0;



	if (task->thread.singlestep_syscall)

arch/um/kernel/ptrace.c

+4 −4
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 


void user_enable_single_step(struct task_struct *child)

{

	child->ptrace |= PT_DTRACE;

	set_tsk_thread_flag(child, TIF_SINGLESTEP);

	child->thread.singlestep_syscall = 0;



#ifdef SUBARCH_SET_SINGLESTEPPING
@@ -21,7 +21,7 @@ void user_enable_single_step(struct task_struct *child) 


void user_disable_single_step(struct task_struct *child)

{

	child->ptrace &= ~PT_DTRACE;

	clear_tsk_thread_flag(child, TIF_SINGLESTEP);

	child->thread.singlestep_syscall = 0;



#ifdef SUBARCH_SET_SINGLESTEPPING
@@ -120,7 +120,7 @@ static void send_sigtrap(struct uml_pt_regs *regs, int error_code) 
}



/*

 * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and

 * XXX Check TIF_SINGLESTEP for singlestepping check and

 * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check

 */

int syscall_trace_enter(struct pt_regs *regs)
@@ -144,7 +144,7 @@ void syscall_trace_leave(struct pt_regs *regs) 
	audit_syscall_exit(regs);



	/* Fake a debug trap */

	if (ptraced & PT_DTRACE)

	if (test_thread_flag(TIF_SINGLESTEP))

		send_sigtrap(&regs->regs, 0);



	if (!test_thread_flag(TIF_SYSCALL_TRACE))

arch/um/kernel/signal.c

+2 −2
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 
	unsigned long sp;

	int err;



	if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))

	if (test_thread_flag(TIF_SINGLESTEP) && (current->ptrace & PT_PTRACED))

		singlestep = 1;



	/* Did we come from a system call? */
@@ -128,7 +128,7 @@ void do_signal(struct pt_regs *regs) 
	 * on the host.  The tracing thread will check this flag and

	 * PTRACE_SYSCALL if necessary.

	 */

	if (current->ptrace & PT_DTRACE)

	if (test_thread_flag(TIF_SINGLESTEP))

		current->thread.singlestep_syscall =

			is_syscall(PT_REGS_IP(&current->thread.regs));