From: Todd Poynor <toddpoynor@google.com>
Date: Wed, 3 Jul 2013 22:48:04 +0000 (-0700)
Subject: ARM: kgdb: ignore breakpoint instructions from user mode
X-Git-Tag: firefly_0821_release~4090^2~517
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c4715194082e79c7fb8e82e0f373f27a01ed3676;p=firefly-linux-kernel-4.4.55.git

ARM: kgdb: ignore breakpoint instructions from user mode

Avoid conflicts with user mode usage of the same instructions, as with
Clang -ftrapv.

Change-Id: I12d1c6d8f94376bfd2503cb0be843d7e478fb6ea
Signed-off-by: Todd Poynor <toddpoynor@google.com>
---

diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index 778c2f7024ff..b321c8fbb87d 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -144,6 +144,8 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
 
 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
 {
+	if (user_mode(regs))
+		return -1;
 	kgdb_handle_exception(1, SIGTRAP, 0, regs);
 
 	return 0;
@@ -151,6 +153,8 @@ static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
 
 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
 {
+	if (user_mode(regs))
+		return -1;
 	compiled_break = 1;
 	kgdb_handle_exception(1, SIGTRAP, 0, regs);