[PATCH] x86/mce: remove unused mce_vaddr

[PATCH] x86/mce: remove unused mce_vaddr

[Miaohe Lin]

Since commit a6e3cf70b772 ("x86/mce: Change to not send SIGBUS error during
copy from user"), mce_vaddr is not used anymore. Remove it and clean up the
relevant code.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 arch/x86/kernel/cpu/mce/severity.c | 7 +------
 include/linux/sched.h              | 1 -
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index c4477162c07d..0acc0039de81 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -252,12 +252,7 @@ static bool is_copy_from_user(struct pt_regs *regs)
 		return false;
 	}
 
-	if (fault_in_kernel_space(addr))
-		return false;
-
-	current->mce_vaddr = (void __user *)addr;
-
-	return true;
+	return !fault_in_kernel_space(addr);
 }
 
 /*
diff --git a/include/linux/sched.h b/include/linux/sched.h
index eed5d65b8d1f..3054a7087230 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1493,7 +1493,6 @@ struct task_struct {
 #endif
 
 #ifdef CONFIG_X86_MCE
-	void __user			*mce_vaddr;
 	__u64				mce_kflags;
 	u64				mce_addr;
 	__u64				mce_ripv : 1,
-- 
2.27.0

Re: [PATCH] x86/mce: remove unused mce_vaddr

[Alison Schofield]

On Sun, May 28, 2023 at 07:35:45PM +0800, Miaohe Lin wrote:
> Since commit a6e3cf70b772 ("x86/mce: Change to not send SIGBUS error during
> copy from user"), mce_vaddr is not used anymore. Remove it and clean up the
> relevant code.

Hi Miaohe,

Not so sure that the 'clean up' part is useful. See below.


> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>  arch/x86/kernel/cpu/mce/severity.c | 7 +------
>  include/linux/sched.h              | 1 -
>  2 files changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
> index c4477162c07d..0acc0039de81 100644
> --- a/arch/x86/kernel/cpu/mce/severity.c
> +++ b/arch/x86/kernel/cpu/mce/severity.c
> @@ -252,12 +252,7 @@ static bool is_copy_from_user(struct pt_regs *regs)
>  		return false;
>  	}
>  
> -	if (fault_in_kernel_space(addr))
> -		return false;
> -
> -	current->mce_vaddr = (void __user *)addr;
> -
> -	return true;
> +	return !fault_in_kernel_space(addr);
>  }


Refactoring the return is unnecessary and seems less readable.
How about removing the assignment, and leaving the rest, as is:

diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index c4477162c07d..1c03221ddcb1 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -255,8 +255,6 @@ static bool is_copy_from_user(struct pt_regs *regs)
        if (fault_in_kernel_space(addr))
                return false;
 
-       current->mce_vaddr = (void __user *)addr;
-
        return true;
 }


Alison




>  
>  /*
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index eed5d65b8d1f..3054a7087230 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1493,7 +1493,6 @@ struct task_struct {
>  #endif
>  
>  #ifdef CONFIG_X86_MCE
> -	void __user			*mce_vaddr;
>  	__u64				mce_kflags;
>  	u64				mce_addr;
>  	__u64				mce_ripv : 1,
> -- 
> 2.27.0
> 

Re: [PATCH] x86/mce: remove unused mce_vaddr

[Miaohe Lin]

On 2023/5/31 3:16, Alison Schofield wrote:
> On Sun, May 28, 2023 at 07:35:45PM +0800, Miaohe Lin wrote:
>> Since commit a6e3cf70b772 ("x86/mce: Change to not send SIGBUS error during
>> copy from user"), mce_vaddr is not used anymore. Remove it and clean up the
>> relevant code.
> 
> Hi Miaohe,
> 
> Not so sure that the 'clean up' part is useful. See below.
> 
> 
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>>  arch/x86/kernel/cpu/mce/severity.c | 7 +------
>>  include/linux/sched.h              | 1 -
>>  2 files changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
>> index c4477162c07d..0acc0039de81 100644
>> --- a/arch/x86/kernel/cpu/mce/severity.c
>> +++ b/arch/x86/kernel/cpu/mce/severity.c
>> @@ -252,12 +252,7 @@ static bool is_copy_from_user(struct pt_regs *regs)
>>  		return false;
>>  	}
>>  
>> -	if (fault_in_kernel_space(addr))
>> -		return false;
>> -
>> -	current->mce_vaddr = (void __user *)addr;
>> -
>> -	return true;
>> +	return !fault_in_kernel_space(addr);
>>  }
> 
> 
> Refactoring the return is unnecessary and seems less readable.
> How about removing the assignment, and leaving the rest, as is:
> 
> diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
> index c4477162c07d..1c03221ddcb1 100644
> --- a/arch/x86/kernel/cpu/mce/severity.c
> +++ b/arch/x86/kernel/cpu/mce/severity.c
> @@ -255,8 +255,6 @@ static bool is_copy_from_user(struct pt_regs *regs)
>         if (fault_in_kernel_space(addr))
>                 return false;
>  
> -       current->mce_vaddr = (void __user *)addr;
> -
>         return true;
>  }
> 

Sounds good to me. Will do it in v2. Thanks for your advice.