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-rw-r--r--arch/arm64/kernel/debug-monitors.c88
1 files changed, 87 insertions, 1 deletions
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 4ae68579031d..636ba8b6240b 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -187,6 +187,48 @@ static void clear_regs_spsr_ss(struct pt_regs *regs)
regs->pstate = spsr;
}
+/* EL1 Single Step Handler hooks */
+static LIST_HEAD(step_hook);
+DEFINE_RWLOCK(step_hook_lock);
+
+void register_step_hook(struct step_hook *hook)
+{
+ write_lock(&step_hook_lock);
+ list_add(&hook->node, &step_hook);
+ write_unlock(&step_hook_lock);
+}
+
+void unregister_step_hook(struct step_hook *hook)
+{
+ write_lock(&step_hook_lock);
+ list_del(&hook->node);
+ write_unlock(&step_hook_lock);
+}
+
+/*
+ * Call registered single step handers
+ * There is no Syndrome info to check for determining the handler.
+ * So we call all the registered handlers, until the right handler is
+ * found which returns zero.
+ */
+static int call_step_hook(struct pt_regs *regs, unsigned int esr)
+{
+ struct step_hook *hook;
+ int retval = DBG_HOOK_ERROR;
+
+ read_lock(&step_hook_lock);
+
+ list_for_each_entry(hook, &step_hook, node) {
+ retval = hook->fn(regs, esr);
+ if (retval == DBG_HOOK_HANDLED)
+ break;
+ }
+
+ read_unlock(&step_hook_lock);
+
+ return retval;
+}
+
static int single_step_handler(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
@@ -214,7 +256,9 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
*/
user_rewind_single_step(current);
} else {
- /* TODO: route to KGDB */
+ if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED)
+ return 0;
+
pr_warning("Unexpected kernel single-step exception at EL1\n");
/*
* Re-enable stepping since we know that we will be
@@ -226,11 +270,53 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
return 0;
}
+/*
+ * Breakpoint handler is re-entrant as another breakpoint can
+ * hit within breakpoint handler, especically in kprobes.
+ * Use reader/writer locks instead of plain spinlock.
+ */
+static LIST_HEAD(break_hook);
+DEFINE_RWLOCK(break_hook_lock);
+
+void register_break_hook(struct break_hook *hook)
+{
+ write_lock(&break_hook_lock);
+ list_add(&hook->node, &break_hook);
+ write_unlock(&break_hook_lock);
+}
+
+void unregister_break_hook(struct break_hook *hook)
+{
+ write_lock(&break_hook_lock);
+ list_del(&hook->node);
+ write_unlock(&break_hook_lock);
+}
+
+static int call_break_hook(struct pt_regs *regs, unsigned int esr)
+{
+ struct break_hook *hook;
+ int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL;
+
+ read_lock(&break_hook_lock);
+ list_for_each_entry(hook, &break_hook, node)
+ if ((esr & hook->esr_mask) == hook->esr_val)
+ fn = hook->fn;
+ read_unlock(&break_hook_lock);
+
+ return fn ? fn(regs, esr) : DBG_HOOK_ERROR;
+}
+
static int brk_handler(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
siginfo_t info;
+ if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED)
+ return 0;
+
+ pr_warn("unexpected brk exception at %lx, esr=0x%x\n",
+ (long)instruction_pointer(regs), esr);
+
if (!user_mode(regs))
return -EFAULT;