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b=mEDnYPSIuWqRIAzs1+UjTshYOL7H74J8SeQyFep4Iy/ZC2pmYCa/pzGcdzhiKOB6Z4QLpAA4w0dInruDgr9bbHHodZZN4+c2nYya52hv6tziFqeSSOTNTVmefiipMxBA/pIEs0Mzds9sT8eaCKOY+DBK9ULgLA7bS7NUTiSoqPo= Received: from localhost.localdomain(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WQr2xAj_1741326247 cluster:ay36) by smtp.aliyun-inc.com; Fri, 07 Mar 2025 13:44:07 +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, xueshuai@linux.alibaba.com Subject: [PATCH v4 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context Date: Fri, 7 Mar 2025 13:44:02 +0800 Message-ID: <20250307054404.73877-2-xueshuai@linux.alibaba.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250307054404.73877-1-xueshuai@linux.alibaba.com> References: <20250307054404.73877-1-xueshuai@linux.alibaba.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Queue-Id: C3C5540006 X-Rspamd-Server: rspam09 X-Stat-Signature: 64i9o9ejjukqgzw1w9ceb47soy7chi7k X-HE-Tag: 1741326252-572169 X-HE-Meta: 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 JeheMCz7 Q8/ft5L8DISlnH80tZGTwQ9MjvGOYldJYr+MFVdHtI4v8shEoIuH6TuvggDjHWY6VnoLGnBU8SHTjoZRi6A2zkP5z1MTplUQPdlMJp8G69CtmKeQwWflO5tzRaZ1ywzp2ywil2lHIIlnsf37fKNEjJ7NBB8vVnuKuLEiKMSDzW/A34WzCb0Ibpj2HN0L8vgtK+wYT9cJqFoSOT85LFeE/lAGuozZKNM3wRXNJPQtq67DracKPif2/rGoiWikOB9J5Gb67Jxuay3jZeQUpRmRn3L0c8FDOuC8JvA8m/1xDulzFYP95+9H6xTud8338VKijvZzoNXxmzDPB1eNGabKfNiI1NoHCtruhc+g45TGB9dyzZ895pAXWTyvGMTsm9e1q898QLrN/bUtUk814o8zYYPCLEN44ATNf5Z6S7Ww+OwookkE= 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 Acked-by: Borislav Petkov (AMD) --- 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;