[RFC PATCH v3 15/26] early kprobes: x86: directly modify code.

From: Wang Nan
Date: Fri Feb 13 2015 - 00:52:54 EST


When registering early kprobes, SMP should has not been enabled, so
doesn't require synchronization in text_poke_bp(). Simply memcpy is
enough.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
arch/x86/kernel/kprobes/opt.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 0dd8d08..21847ab 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -36,6 +36,7 @@
#include <asm/alternative.h>
#include <asm/insn.h>
#include <asm/debugreg.h>
+#include <asm/tlbflush.h>

#include "common.h"

@@ -397,8 +398,15 @@ void arch_optimize_kprobes(struct list_head *oplist)
insn_buf[0] = RELATIVEJUMP_OPCODE;
*(s32 *)(&insn_buf[1]) = rel;

- text_poke_bp(op->kp.addr, insn_buf, RELATIVEJUMP_SIZE,
- op->optinsn.insn);
+ if (unlikely(kprobes_is_early())) {
+ BUG_ON(!(op->kp.flags & KPROBE_FLAG_EARLY));
+ memcpy(op->kp.addr, insn_buf, RELATIVEJUMP_SIZE);
+ local_flush_tlb();
+ sync_core();
+ } else {
+ text_poke_bp(op->kp.addr, insn_buf, RELATIVEJUMP_SIZE,
+ op->optinsn.insn);
+ }

list_del_init(&op->list);
}
--
1.8.4

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