Use stop_machine() to wrap code modification for x86 when optimizing
early kprobes. Since early kprobes are registered before smp inited,
text_poke_bp() is not ready at that time. This patch use stop_machine()
based code modification for early kprobes.
At very early stage, stop_machine() is simply irq operations. After
kprobes fully initianized, we will use text_poke_bp(). Only kprobes
registered after cpu_stop_init() before init_kprobes() will use real
stop_machine().
Signed-off-by: Wang Nan <wangn...@huawei.com>
---
arch/x86/kernel/kprobes/opt.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 7b3b9d1..ef3c0be 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -28,6 +28,7 @@
#include <linux/kdebug.h>
#include <linux/kallsyms.h>
#include <linux/ftrace.h>
+#include <linux/stop_machine.h>
#include <asm/cacheflush.h>
#include <asm/desc.h>
@@ -377,6 +378,20 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe
*op,
return 0;
}
+struct optimize_kprobe_early_param {
+ struct optimized_kprobe *op;
+ u8 *insn_buf;
+};
+
+static int optimize_kprobe_stop_machine(void *data)
+{
+ struct optimize_kprobe_early_param *param = data;
+
+ text_poke_early(param->op->kp.addr,
+ param->insn_buf, RELATIVEJUMP_SIZE);
+ return 0;
+}
+
/*
* Replace breakpoints (int3) with relative jumps.
* Caller must call with locking kprobe_mutex and text_mutex.
@@ -399,8 +414,17 @@ 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())) {
+ struct optimize_kprobe_early_param p = {
+ .op = op,
+ .insn_buf = insn_buf,
+ };
+
+ stop_machine(optimize_kprobe_stop_machine, &p, NULL);
+ } 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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