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hw-breakpoints: Keep track of user disabled breakpoints
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>
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@ -595,7 +595,7 @@ static unsigned long ptrace_get_dr7(struct perf_event *bp[])
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static struct perf_event *
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static struct perf_event *
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ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
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ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
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struct task_struct *tsk)
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struct task_struct *tsk, int disabled)
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{
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{
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int err;
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int err;
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int gen_len, gen_type;
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int gen_len, gen_type;
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@ -616,7 +616,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
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attr = bp->attr;
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attr = bp->attr;
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attr.bp_len = gen_len;
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attr.bp_len = gen_len;
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attr.bp_type = gen_type;
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attr.bp_type = gen_type;
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attr.disabled = 0;
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attr.disabled = disabled;
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return modify_user_hw_breakpoint(bp, &attr, bp->callback, tsk);
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return modify_user_hw_breakpoint(bp, &attr, bp->callback, tsk);
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}
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}
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@ -655,13 +655,21 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
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*/
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*/
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if (!second_pass)
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if (!second_pass)
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continue;
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continue;
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thread->ptrace_bps[i] = NULL;
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thread->ptrace_bps[i] = NULL;
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unregister_hw_breakpoint(bp);
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bp = ptrace_modify_breakpoint(bp, len, type,
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tsk, 1);
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if (IS_ERR(bp)) {
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rc = PTR_ERR(bp);
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thread->ptrace_bps[i] = NULL;
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break;
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}
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thread->ptrace_bps[i] = bp;
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}
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}
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continue;
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continue;
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}
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}
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bp = ptrace_modify_breakpoint(bp, len, type, tsk);
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bp = ptrace_modify_breakpoint(bp, len, type, tsk, 0);
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/* Incorrect bp, or we have a bug in bp API */
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/* Incorrect bp, or we have a bug in bp API */
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if (IS_ERR(bp)) {
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if (IS_ERR(bp)) {
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