[RFC,v3,13/26] early kprobes: ARM: directly modify code.

Commit Message

Wang Nan Feb. 13, 2015, 5:40 a.m. UTC

For early kprobe, we can simply patch text because we are in a relative
simple environment.

Signed-off-by: Wang Nan <[e-mail]>
---
 arch/arm/probes/kprobes/opt-arm.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Patch

diff --git a/arch/arm/probes/kprobes/opt-arm.c b/arch/arm/probes/kprobes/opt-arm.c
index bcdecc2..43446df 100644
--- a/arch/arm/probes/kprobes/opt-arm.c
+++ b/arch/arm/probes/kprobes/opt-arm.c
@@ -330,8 +330,18 @@  void __kprobes arch_optimize_kprobes(struct list_head *oplist)
 		 * Similar to __arch_disarm_kprobe, operations which
 		 * removing breakpoints must be wrapped by stop_machine
 		 * to avoid racing.
+		 *
+		 * If this function is called before kprobes initialized,
+		 * the kprobe should be an early kprobe, the instruction
+		 * is not armed with breakpoint. There should be only
+		 * one core now, so directly __patch_text is enough.
 		 */
-		kprobes_remove_breakpoint(op->kp.addr, insn);
+		if (unlikely(kprobes_is_early())) {
+			BUG_ON(!(op->kp.flags & KPROBE_FLAG_EARLY));
+			__patch_text(op->kp.addr, insn);
+		} else {
+			kprobes_remove_breakpoint(op->kp.addr, insn);
+		}
 
 		list_del_init(&op->list);
 	}