[PATCH] x86/ftrace: usr ftrace_write to simplify code

[PATCH] x86/ftrace: usr ftrace_write to simplify code

[Cheng Jian]

ftrace_write() can be used directly in ftrace_modify_code_direct(),
that make the code more brief.

Signed-off-by: Cheng Jian <cj.chengjian@huawei.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];
-- 
2.17.1

Re: [PATCH] x86/ftrace: usr ftrace_write to simplify code

[chengjian (D)]

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@huawei.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];

Re: [PATCH] x86/ftrace: usr ftrace_write to simplify code

[Steven Rostedt]

On Tue, 14 Jan 2020 09:37:41 +0800
"chengjian (D)" <cj.chengjian@huawei.com> wrote:

> I am sorry.
> 
> usr => use in subject.
> 
> I will resend this patch.
> 

I already pulled the original patch into my queue, but I did fix the
typo (and also capitalized the first word to "Use").

It's currently running through my tests.

-- Steve

Re: [PATCH] x86/ftrace: usr ftrace_write to simplify code

[chengjian (D)]

On 2020/1/14 11:34, Steven Rostedt wrote:
> On Tue, 14 Jan 2020 09:37:41 +0800
> "chengjian (D)" <cj.chengjian@huawei.com> wrote:
>
>> I am sorry.
>>
>> usr => use in subject.
>>
>> I will resend this patch.
>>
> I already pulled the original patch into my queue, but I did fix the
> typo (and also capitalized the first word to "Use").
>
> It's currently running through my tests.
>
> -- Steve
>
> .


Thank you very much, Steven.


But peter has optimized the logic here, and those patches have been

applied to the tip branch, so my patch may not be needed.


https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=768ae4406a5cab7e8702550f2446dbeb377b798d

https://lkml.org/lkml/2020/1/14/123



-- Cheng Jian