From: Pratyush Anand <panand@redhat.com>
Date: Wed, 2 Nov 2016 09:10:44 +0000 (+0530)
Subject: arm64: Handle TRAP_BRKPT for user mode as well
X-Git-Tag: v4.10-rc1~135^2~40
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=53d07e21854de064d9625853b8303357482b25b1;p=platform%2Fkernel%2Flinux-exynos.git

arm64: Handle TRAP_BRKPT for user mode as well

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 <panand@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index a8f8de0..605df76 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;
 	}