| Message ID | 1425359345-38714-4-git-send-email-wangnan0@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue 2015-03-03 13:09:05, Wang Nan wrote: > Before ftrace convertin instruction to nop, if an early kprobe is > registered then unregistered, without this patch its first bytes will > be replaced by head of NOP, which may confuse ftrace. > > Actually, since we have a patch which convert ftrace entry to nop > when probing, this problem should never be triggered. Provide it for > safety. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > --- > arch/x86/kernel/kprobes/core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c > index 87beb64..c7d304d 100644 > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -225,6 +225,9 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) > struct kprobe *kp; > unsigned long faddr; > > + if (!kprobes_on_ftrace_initialized) > + return addr; This is not correct. The function has to return a buffer with the original code also when it is modified by normal kprobes. If it is a normal Kprobe, it reads the current code and replaces the first byte (INT3 instruction) with the saved kp->opcode. > + > kp = get_kprobe((void *)addr); > faddr = ftrace_location(addr); IMHO, the proper fix might be to replace the above line with if (kprobes_on_ftrace_initialized) faddr = ftrace_location(addr); else faddr = 0UL; By other words, it might pretend that it is not a ftrace location when the ftrace is not ready yet. Or is the code modified another special way when it is a ftrace location but ftrace has not been initialized yet? Best Regards, Petr > /* > -- > 1.8.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 87beb64..c7d304d 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -225,6 +225,9 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) struct kprobe *kp; unsigned long faddr; + if (!kprobes_on_ftrace_initialized) + return addr; + kp = get_kprobe((void *)addr); faddr = ftrace_location(addr); /*
Before ftrace convertin instruction to nop, if an early kprobe is registered then unregistered, without this patch its first bytes will be replaced by head of NOP, which may confuse ftrace. Actually, since we have a patch which convert ftrace entry to nop when probing, this problem should never be triggered. Provide it for safety. Signed-off-by: Wang Nan <wangnan0@huawei.com> --- arch/x86/kernel/kprobes/core.c | 3 +++ 1 file changed, 3 insertions(+)