[PATCH V3 3/6] arm64: Handle TRAP_TRACE for user mode as well

Pratyush Anand
2016-11-02T09:11:16Z

uprobe registers a handler at step_hook. So, single_step_handler now
checks for user mode as well if there is a valid hook.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
arch/arm64/kernel/debug-monitors.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 73ae90ef434c..a8f8de012250 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -226,6 +226,8 @@ static void send_user_sigtrap(int si_code)
static int single_step_handler(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
+ bool handler_found = false;
+
/*
* If we are stepping a pending breakpoint, call the hw_breakpoint
* handler first.
@@ -233,7 +235,14 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
if (!reinstall_suspended_bps(regs))
return 0;

- if (user_mode(regs)) {
+#ifdef CONFIG_KPROBES
+ if (kprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED)
+ handler_found = true;
+#endif
+ if (!handler_found && call_step_hook(regs, esr) == DBG_HOOK_HANDLED)
+ handler_found = true;
+
+ if (!handler_found && user_mode(regs)) {
send_user_sigtrap(TRAP_TRACE);

/*
@@ -243,15 +252,8 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
* to the active-not-pending state).
*/
user_rewind_single_step(current);
- } else {
-#ifdef CONFIG_KPROBES
- if (kprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED)
- return 0;
-#endif
- if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED)
- return 0;
-
- pr_warning("Unexpected kernel single-step exception at EL1\n");
+ } else if (!handler_found) {
+ pr_warn("Unexpected kernel single-step exception at EL1\n");
/*
* Re-enable stepping since we know that we will be
* returning to regs.
--
2.7.4