1 // SPDX-License-Identifier: GPL-2.0-only 2 3 #include <linux/uaccess.h> 4 #include <linux/kernel.h> 5 6 #ifdef CONFIG_X86_64 7 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) 8 { 9 unsigned long vaddr = (unsigned long)unsafe_src; 10 11 /* 12 * Do not allow userspace addresses. This disallows 13 * normal userspace and the userspace guard page: 14 */ 15 if (vaddr < TASK_SIZE_MAX + PAGE_SIZE) 16 return false; 17 18 /* 19 * Allow everything during early boot before 'x86_virt_bits' 20 * is initialized. Needed for instruction decoding in early 21 * exception handlers. 22 */ 23 if (!boot_cpu_data.x86_virt_bits) 24 return true; 25 26 return __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); 27 } 28 #else 29 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) 30 { 31 return (unsigned long)unsafe_src >= TASK_SIZE_MAX; 32 } 33 #endif 34