linux-kernel - RE: [PATCH v3 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context

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Message-ID: <SJ1PR11MB60837DE67D37F45B0D106C9CFCCA2@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Thu, 6 Mar 2025 18:15:26 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: Shuai Xue <xueshuai@...ux.alibaba.com>, "bp@...en8.de" <bp@...en8.de>,
	"peterz@...radead.org" <peterz@...radead.org>, "catalin.marinas@....com"
	<catalin.marinas@....com>, "yazen.ghannam@....com" <yazen.ghannam@....com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linmiaohe@...wei.com" <linmiaohe@...wei.com>, "nao.horiguchi@...il.com"
	<nao.horiguchi@...il.com>
CC: "tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com"
	<mingo@...hat.com>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>,
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	<baolin.wang@...ux.alibaba.com>, "tianruidong@...ux.alibaba.com"
	<tianruidong@...ux.alibaba.com>
Subject: RE: [PATCH v3 1/3] x86/mce: Use is_copy_from_user() to determine
 copy-from-user context

> diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
> index dac4d64dfb2a..cb021058165f 100644
> --- a/arch/x86/kernel/cpu/mce/severity.c
> +++ b/arch/x86/kernel/cpu/mce/severity.c
> @@ -300,13 +300,12 @@ static noinstr int error_context(struct mce *m, struct pt_regs *regs)
>       copy_user  = is_copy_from_user(regs);
>       instrumentation_end();
>
> -     switch (fixup_type) {
> -     case EX_TYPE_UACCESS:
> -             if (!copy_user)
> -                     return IN_KERNEL;
> -             m->kflags |= MCE_IN_KERNEL_COPYIN;
> -             fallthrough;
> +     if (copy_user) {
> +             m->kflags |= MCE_IN_KERNEL_COPYIN | MCE_IN_KERNEL_COPYIN;

You have " MCE_IN_KERNEL_COPYIN" twice here.

> +             return IN_KERNEL_RECOV
> +     }
>
> +     switch (fixup_type) {
>       case EX_TYPE_FAULT_MCE_SAFE:
>       case EX_TYPE_DEFAULT_MCE_SAFE:
>               m->kflags |= MCE_IN_KERNEL_RECOV;
> --

-Tony