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b=x7IIJBkI0QNLH/IrNRXcMZgEVnEjmnhgQ/JwLH4KlthuH/wrnc4Sqg0ABt74RZvog9LBevKXkfPYPDXjpoOWXsJ0LLKAZuIFINi9JAssf+WY8kMbKLXqlwAXU5wo9m7WHk05Pn7fqpW0T/xWwZm3x3cwu84hdwBE13mEBS3aWQw= Received: from localhost.localdomain(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WQmzy.1_1741227033 cluster:ay36) by smtp.aliyun-inc.com; Thu, 06 Mar 2025 10:10:34 +0800 From: Shuai Xue To: tony.luck@intel.com, bp@alien8.de, peterz@infradead.org, catalin.marinas@arm.com, yazen.ghannam@amd.com, akpm@linux-foundation.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com Cc: tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, jpoimboe@kernel.org, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, baolin.wang@linux.alibaba.com, tianruidong@linux.alibaba.com Subject: [PATCH v3 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context Date: Thu, 6 Mar 2025 10:10:29 +0800 Message-ID: <20250306021031.5538-2-xueshuai@linux.alibaba.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250306021031.5538-1-xueshuai@linux.alibaba.com> References: <20250306021031.5538-1-xueshuai@linux.alibaba.com> MIME-Version: 1.0 X-Rspamd-Server: rspam02 X-Stat-Signature: p8xzdgsx95s9rh47ai3u869gpiku8odo X-Rspamd-Queue-Id: 1ED321A0002 X-Rspam-User: X-HE-Tag: 1741227038-725891 X-HE-Meta: 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 KMdPJrkS DGPLuwEOM2A1GCs2lN5GaXegCbCTWwa9Sn+og5yDBRoMa+l/ykM/4ZOj1SwqdzgEdf6F5m4HAGfXQp9SVvsZGdM8lv2xsX91a1BY4XG+7v+eQvjBpY5SmHK5nwrrXljPtfOzUkY484yRO0/vNGy/40vbThJ1XXSldWojy6XvZeAx7+YOhto6k4yzalz0xz7RboKlsEclDdSt/JojADJBt6f8pOOdKqsH2wcyErRBHc777Fa6/5W4Zh3BiTpRUYIM0OSLdKBN2iBOBoO5Ld/XwJntpAv7L5D4AuEHflkiVjbAJScPrglvZOeZYqdCgtj+KlwJMkbYUX92jepTBhHVlFYwutPIwjXgS39YD64/B81aUhKyvaiervLntLVK6BcWjjOm+Bh4c5kND1WHHAiulkndaS/ZWU8ExVCmNYM6tD1ti3y4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000030, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Commit 4c132d1d844a ("x86/futex: Remove .fixup usage") introduced a new extable fixup type, EX_TYPE_EFAULT_REG, and commit 4c132d1d844a ("x86/futex: Remove .fixup usage") updated the extable fixup type for copy-from-user operations, changing it from EX_TYPE_UACCESS to EX_TYPE_EFAULT_REG. The error context for copy-from-user operations no longer functions as an in-kernel recovery context. Consequently, the error context for copy-from-user operations no longer functions as an in-kernel recovery context, resulting in kernel panics with the message: "Machine check: Data load in unrecoverable area of kernel." The critical aspect is identifying whether the error context involves a read from user memory. We do not care about the ex-type if we know its a MOV reading from userspace. is_copy_from_user() return true when both of the following conditions are met: - the current instruction is copy - source address is user memory So, use is_copy_from_user() to determin if a context is copy user directly. Fixes: 4c132d1d844a ("x86/futex: Remove .fixup usage") Suggested-by: Peter Zijlstra Cc: stable@vger.kernel.org Signed-off-by: Shuai Xue --- 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..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; + 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;