From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linux-Kernel <linux-kernel@vger.kernel.org>,
mingo@redhat.com, konrad.wilk@oracle.com, dwmw@amazon.co.uk,
tglx@linutronix.de,
Srinivas REDDY Eeda <srinivas.eeda@oracle.com>,
bp@suse.de, hpa@zytor.com
Subject: Re: [PATCH 3/3] kprobes/x86: Simplify indirect-jump check in retpoline
Date: Wed, 31 Oct 2018 14:01:20 +0800 [thread overview]
Message-ID: <849ae148-85cd-5f46-d98b-b827cc9c605c@oracle.com> (raw)
In-Reply-To: <20181030083650.GB1459@hirez.programming.kicks-ass.net>
On 2018/10/30 16:36, Peter Zijlstra wrote:
> On Mon, Oct 29, 2018 at 11:55:06PM -0700, Zhenzhong Duan wrote:
>> Since CONFIG_RETPOLINE hard depends on compiler support now, so
>> replacing indirect-jump check with the range check is safe in that case.
>
> Can we put kprobes on module init text before we run alternatives on it?
Forgive me I doesn't understand your question. Do you mean this patch
impact kprobes on module init text?
>
>> @@ -240,20 +242,16 @@ static int insn_jump_into_range(struct insn *insn, unsigned long start, int len)
>>
>> static int insn_is_indirect_jump(struct insn *insn)
>> {
>> - int ret = __insn_is_indirect_jump(insn);
>> + int ret;
>>
>> #ifdef CONFIG_RETPOLINE
>> - /*
>> - * Jump to x86_indirect_thunk_* is treated as an indirect jump.
>> - * Note that even with CONFIG_RETPOLINE=y, the kernel compiled with
>> - * older gcc may use indirect jump. So we add this check instead of
>> - * replace indirect-jump check.
>> - */
>> - if (!ret)
>> + /* Jump to x86_indirect_thunk_* is treated as an indirect jump. */
>> ret = insn_jump_into_range(insn,
>> (unsigned long)__indirect_thunk_start,
>> (unsigned long)__indirect_thunk_end -
>> (unsigned long)__indirect_thunk_start);
>> +#else
>> + ret = __insn_is_indirect_jump(insn);
>> #endif
>> return ret;
>> }
>
> The resulting code is indented wrong.
>
Oh, yes. Thanks for point out.
Zhenzhong
next prev parent reply other threads:[~2018-10-31 6:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-30 6:55 [PATCH 3/3] kprobes/x86: Simplify indirect-jump check in retpoline Zhenzhong Duan
2018-10-30 8:36 ` Peter Zijlstra
2018-10-31 6:01 ` Zhenzhong Duan [this message]
2018-10-31 13:53 ` Peter Zijlstra
2018-10-31 14:00 ` Peter Zijlstra
2018-11-01 2:02 ` Zhenzhong Duan
2018-11-01 8:56 ` Peter Zijlstra
2018-11-01 9:21 ` Zhenzhong Duan
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