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-rw-r--r--arch/x86/kernel/kgdb.c51
-rw-r--r--include/linux/hw_breakpoint.h2
-rw-r--r--kernel/hw_breakpoint.c52
3 files changed, 95 insertions, 10 deletions
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 62bea7307eaa..bfba6019d762 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -239,6 +239,49 @@ static void kgdb_correct_hw_break(void)
hw_breakpoint_restore();
}
+static int hw_break_reserve_slot(int breakno)
+{
+ int cpu;
+ int cnt = 0;
+ struct perf_event **pevent;
+
+ for_each_online_cpu(cpu) {
+ cnt++;
+ pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+ if (dbg_reserve_bp_slot(*pevent))
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ for_each_online_cpu(cpu) {
+ cnt--;
+ if (!cnt)
+ break;
+ pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+ dbg_release_bp_slot(*pevent);
+ }
+ return -1;
+}
+
+static int hw_break_release_slot(int breakno)
+{
+ struct perf_event **pevent;
+ int cpu;
+
+ for_each_online_cpu(cpu) {
+ pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+ if (dbg_release_bp_slot(*pevent))
+ /*
+ * The debugger is responisble for handing the retry on
+ * remove failure.
+ */
+ return -1;
+ }
+ return 0;
+}
+
static int
kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
{
@@ -250,6 +293,10 @@ kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
if (i == 4)
return -1;
+ if (hw_break_release_slot(i)) {
+ printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
+ return -1;
+ }
breakinfo[i].enabled = 0;
return 0;
@@ -316,6 +363,10 @@ kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
return -1;
}
breakinfo[i].addr = addr;
+ if (hw_break_reserve_slot(i)) {
+ breakinfo[i].addr = 0;
+ return -1;
+ }
breakinfo[i].enabled = 1;
return 0;
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index 41235c93e4e9..070ba0621738 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -75,6 +75,8 @@ extern int __register_perf_hw_breakpoint(struct perf_event *bp);
extern void unregister_hw_breakpoint(struct perf_event *bp);
extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);
+extern int dbg_reserve_bp_slot(struct perf_event *bp);
+extern int dbg_release_bp_slot(struct perf_event *bp);
extern int reserve_bp_slot(struct perf_event *bp);
extern void release_bp_slot(struct perf_event *bp);
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index c030ae657f20..8a5c7d55ac9f 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -243,38 +243,70 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable)
* ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
* + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM
*/
-int reserve_bp_slot(struct perf_event *bp)
+static int __reserve_bp_slot(struct perf_event *bp)
{
struct bp_busy_slots slots = {0};
- int ret = 0;
-
- mutex_lock(&nr_bp_mutex);
fetch_bp_busy_slots(&slots, bp);
/* Flexible counters need to keep at least one slot */
- if (slots.pinned + (!!slots.flexible) == HBP_NUM) {
- ret = -ENOSPC;
- goto end;
- }
+ if (slots.pinned + (!!slots.flexible) == HBP_NUM)
+ return -ENOSPC;
toggle_bp_slot(bp, true);
-end:
+ return 0;
+}
+
+int reserve_bp_slot(struct perf_event *bp)
+{
+ int ret;
+
+ mutex_lock(&nr_bp_mutex);
+
+ ret = __reserve_bp_slot(bp);
+
mutex_unlock(&nr_bp_mutex);
return ret;
}
+static void __release_bp_slot(struct perf_event *bp)
+{
+ toggle_bp_slot(bp, false);
+}
+
void release_bp_slot(struct perf_event *bp)
{
mutex_lock(&nr_bp_mutex);
- toggle_bp_slot(bp, false);
+ __release_bp_slot(bp);
mutex_unlock(&nr_bp_mutex);
}
+/*
+ * Allow the kernel debugger to reserve breakpoint slots without
+ * taking a lock using the dbg_* variant of for the reserve and
+ * release breakpoint slots.
+ */
+int dbg_reserve_bp_slot(struct perf_event *bp)
+{
+ if (mutex_is_locked(&nr_bp_mutex))
+ return -1;
+
+ return __reserve_bp_slot(bp);
+}
+
+int dbg_release_bp_slot(struct perf_event *bp)
+{
+ if (mutex_is_locked(&nr_bp_mutex))
+ return -1;
+
+ __release_bp_slot(bp);
+
+ return 0;
+}
int register_perf_hw_breakpoint(struct perf_event *bp)
{