2023-05-28 05:25:25

by Miaohe Lin

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

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 <[email protected]>
---
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

2023-05-30 19:36:21

by Alison Schofield

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

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 <[email protected]>
> ---
> 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
>

2023-06-03 03:55:52

by Miaohe Lin

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

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 <[email protected]>
>> ---
>> 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.