linux-kernel - [RFC 7/8] ARM64: Handle TRAP

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Date:	Wed, 31 Dec 2014 20:51:23 +0530
From:	Pratyush Anand <panand@...hat.com>
To:	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk
Cc:	tixy@...aro.org, ananth@...ibm.com, sandeepa.prabhu@...aro.org,
	catalin.marinas@....com, will.deacon@....com,
	linux-kernel@...r.kernel.org, anil.s.keshavamurthy@...el.com,
	masami.hiramatsu.pt@...achi.com, wcohen@...hat.com,
	oleg@...hat.com, Pratyush Anand <panand@...hat.com>
Subject: [RFC 7/8] 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@...hat.com>
---
 arch/arm64/kernel/debug-monitors.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 2676b8655241..98ba5c8c5141 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -306,6 +306,9 @@ static int brk_handler(unsigned long addr, unsigned int esr,
 {
 	siginfo_t info;
 
+	if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED)
+		return 0;
+
 	if (user_mode(regs)) {
 		info = (siginfo_t) {
 			.si_signo = SIGTRAP,
@@ -315,12 +318,11 @@ static int brk_handler(unsigned long addr, unsigned int esr,
 		};
 
 		force_sig_info(SIGTRAP, &info, current);
-	} else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) {
+		return 0;
+	} else {
 		pr_warning("Unexpected kernel BRK exception at EL1\n");
 		return -EFAULT;
 	}
-
-	return 0;
 }
 
 int aarch32_break_handler(struct pt_regs *regs)
-- 
2.1.0

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