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: <9556c686-d502-4b30-83e1-860154c84cc2@linux.alibaba.com>
Date: Fri, 7 Mar 2025 09:40:01 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: "Luck, Tony" <tony.luck@...el.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>, "hpa@...or.com" <hpa@...or.com>,
 "jpoimboe@...nel.org" <jpoimboe@...nel.org>,
 "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-mm@...ck.org" <linux-mm@...ck.org>,
 "baolin.wang@...ux.alibaba.com" <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



在 2025/3/7 02:15, Luck, Tony 写道:
>> 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.

Sorry, I forgot to format a new patch and send a old version.
The corrected one:

---
  arch/x86/kernel/cpu/mce/severity.c | 11 +++++------
  1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index dac4d64dfb2a..2235a7477436 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_RECOV;
+		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;

Will fix it in next version.


Thanks.
Shuai