linux-kernel - Re: [PATCH] x86/ftrace: usr ftrace

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Date:   Tue, 14 Jan 2020 09:37:41 +0800
From:   "chengjian (D)" <cj.chengjian@...wei.com>
To:     <x86@...nel.org>, <linux-kernel@...r.kernel.org>
CC:     <xiexiuqi@...wei.com>, <huawei.libin@...wei.com>,
        <bobo.shaobowang@...wei.com>, <rostedt@...dmis.org>,
        <mingo@...hat.com>, <tglx@...utronix.de>
Subject: Re: [PATCH] x86/ftrace: usr ftrace_write to simplify code

I am sorry.

usr => use in subject.

I will resend this patch.

  --Cheng Jian

On 2020/1/13 15:33, Cheng Jian wrote:
> ftrace_write() can be used directly in ftrace_modify_code_direct(),
> that make the code more brief.
>
> Signed-off-by: Cheng Jian <cj.chengjian@...wei.com>
> ---
>   arch/x86/kernel/ftrace.c | 24 +++++++++++-------------
>   1 file changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 024c3053dbba..6b36ed2fd04d 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -114,6 +114,16 @@ static const unsigned char *ftrace_nop_replace(void)
>   	return ideal_nops[NOP_ATOMIC5];
>   }
>   
> +static int ftrace_write(unsigned long ip, const char *val, int size)
> +{
> +	ip = text_ip_addr(ip);
> +
> +	if (probe_kernel_write((void *)ip, val, size))
> +		return -EPERM;
> +
> +	return 0;
> +}
> +
>   static int
>   ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
>   		   unsigned const char *new_code)
> @@ -138,10 +148,8 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
>   	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
>   		return -EINVAL;
>   
> -	ip = text_ip_addr(ip);
> -
>   	/* replace the text with the new text */
> -	if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
> +	if (ftrace_write(ip, new_code, MCOUNT_INSN_SIZE))
>   		return -EPERM;
>   
>   	sync_core();
> @@ -326,16 +334,6 @@ int ftrace_int3_handler(struct pt_regs *regs)
>   }
>   NOKPROBE_SYMBOL(ftrace_int3_handler);
>   
> -static int ftrace_write(unsigned long ip, const char *val, int size)
> -{
> -	ip = text_ip_addr(ip);
> -
> -	if (probe_kernel_write((void *)ip, val, size))
> -		return -EPERM;
> -
> -	return 0;
> -}
> -
>   static int add_break(unsigned long ip, const char *old)
>   {
>   	unsigned char replaced[MCOUNT_INSN_SIZE];