[PATCH V3 4/6] arm64: Handle TRAP_BRKPT for user mode as well

[Pratyush Anand]

uprobe is registered at break_hook with a unique ESR code. So, when a
TRAP_BRKPT occurs, call_break_hook checks if it was for uprobe. If not,
then send a SIGTRAP to user.

Signed-off-by: Pratyush Anand <pan...@redhat.com>
---
 arch/arm64/kernel/debug-monitors.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/debug-monitors.c 
b/arch/arm64/kernel/debug-monitors.c
index a8f8de012250..605df76f0a06 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -306,16 +306,20 @@ NOKPROBE_SYMBOL(call_break_hook);
 static int brk_handler(unsigned long addr, unsigned int esr,
                       struct pt_regs *regs)
 {
-       if (user_mode(regs)) {
-               send_user_sigtrap(TRAP_BRKPT);
-       }
+       bool handler_found = false;
+
 #ifdef CONFIG_KPROBES
-       else if ((esr & BRK64_ESR_MASK) == BRK64_ESR_KPROBES) {
-               if (kprobe_breakpoint_handler(regs, esr) != DBG_HOOK_HANDLED)
-                       return -EFAULT;
+       if ((esr & BRK64_ESR_MASK) == BRK64_ESR_KPROBES) {
+               if (kprobe_breakpoint_handler(regs, esr) == DBG_HOOK_HANDLED)
+                       handler_found = true;
        }
 #endif
-       else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) {
+       if (!handler_found && call_break_hook(regs, esr) == DBG_HOOK_HANDLED)
+               handler_found = true;
+
+       if (!handler_found && user_mode(regs)) {
+               send_user_sigtrap(TRAP_BRKPT);
+       } else if (!handler_found) {
                pr_warn("Unexpected kernel BRK exception at EL1\n");
                return -EFAULT;
        }
-- 
2.7.4