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

From: Wang Nan
Date: Fri Feb 13 2015 - 00:50:21 EST


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

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
arch/arm/probes/kprobes/opt-arm.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

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);
}
--
1.8.4

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