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Commit e6a7d607 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

ptrace/x86: simplify the "disable" logic in ptrace_write_dr7() 



ptrace_write_dr7() looks unnecessarily overcomplicated.  We can factor
out ptrace_modify_breakpoint() and do not do "continue" twice, just we
need to pass the proper "disabled" argument to
ptrace_modify_breakpoint().

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7c8df286

arch/x86/kernel/ptrace.c

+15 −25
Original line number Diff line number Diff line
@@ -637,9 +637,7 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data) 
	struct thread_struct *thread = &(tsk->thread);

	unsigned long old_dr7;

	int i, orig_ret = 0, rc = 0;

	int enabled, second_pass = 0;

	unsigned len, type;

	struct perf_event *bp;

	int second_pass = 0;



	data &= ~DR_CONTROL_RESERVED;

	old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
@@ -649,30 +647,22 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data) 
	 * appropriate changes to each.

	 */

	for (i = 0; i < HBP_NUM; i++) {

		enabled = decode_dr7(data, i, &len, &type);

		bp = thread->ptrace_bps[i];

		unsigned len, type;

		bool disabled = !decode_dr7(data, i, &len, &type);

		struct perf_event *bp = thread->ptrace_bps[i];



		if (!enabled) {

			if (bp) {

		if (disabled) {

			/*

				 * Don't unregister the breakpoints right-away,

				 * unless all register_user_hw_breakpoint()

				 * requests have succeeded. This prevents

				 * any window of opportunity for debug

				 * register grabbing by other users.

			 * Don't unregister the breakpoints right-away, unless

			 * all register_user_hw_breakpoint() requests have

			 * succeeded. This prevents any window of opportunity

			 * for debug register grabbing by other users.

			 */

				if (!second_pass)

					continue;



				rc = ptrace_modify_breakpoint(bp, len, type,

							      tsk, 1);

				if (rc)

					break;

			}

			if (!bp || !second_pass)

				continue;

		}



		rc = ptrace_modify_breakpoint(bp, len, type, tsk, 0);

		rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);

		if (rc)

			break;

	}