hw-breakpoints: Keep track of user disabled breakpoints (1cedae72) · Commits · 戴 / test

When we disable a breakpoint through dr7, we unregister it right away, making us lose track of its corresponding address register value. It means that the following sequence would be unsupported: - set address in dr0 - enable it through dr7 - disable it through dr7 - enable it through dr7 because we lost the address register value when we disabled the breakpoint. Don't unregister the disabled breakpoints but rather disable them. Reported-by:

"K.Prasad" <prasad@linux.vnet.ibm.com> Signed-off-by:

Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1259735536-9236-1-git-send-regression-fweisbec@gmail.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ptrace.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -595,7 +595,7 @@ static unsigned long ptrace_get_dr7(struct perf_event *bp[])

		static struct perf_event *
		ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
		struct task_struct *tsk)
		struct task_struct *tsk, int disabled)
		{
		int err;
		int gen_len, gen_type;
		@@ -616,7 +616,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
		attr = bp->attr;
		attr.bp_len = gen_len;
		attr.bp_type = gen_type;
		attr.disabled = 0;
		attr.disabled = disabled;

		return modify_user_hw_breakpoint(bp, &attr, bp->callback, tsk);
		}
		@@ -655,13 +655,21 @@ restore:
		*/
		if (!second_pass)
		continue;

		thread->ptrace_bps[i] = NULL;
		bp = ptrace_modify_breakpoint(bp, len, type,
		tsk, 1);
		if (IS_ERR(bp)) {
		rc = PTR_ERR(bp);
		thread->ptrace_bps[i] = NULL;
		unregister_hw_breakpoint(bp);
		break;
		}
		thread->ptrace_bps[i] = bp;
		}
		continue;
		}

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

		/* Incorrect bp, or we have a bug in bp API */
		if (IS_ERR(bp)) {

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