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>
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 2941b32..04d182a 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -595,7 +595,7 @@
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 @@
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 @@
*/
if (!second_pass)
continue;
+
thread->ptrace_bps[i] = NULL;
- unregister_hw_breakpoint(bp);
+ bp = ptrace_modify_breakpoint(bp, len, type,
+ tsk, 1);
+ if (IS_ERR(bp)) {
+ rc = PTR_ERR(bp);
+ thread->ptrace_bps[i] = NULL;
+ 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)) {
