18c2ecf20Sopenharmony_ci// SPDX-License-Identifier: GPL-2.0-only 28c2ecf20Sopenharmony_ci 38c2ecf20Sopenharmony_ci#include <linux/uaccess.h> 48c2ecf20Sopenharmony_ci#include <linux/kernel.h> 58c2ecf20Sopenharmony_ci 68c2ecf20Sopenharmony_ci#ifdef CONFIG_X86_64 78c2ecf20Sopenharmony_cibool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) 88c2ecf20Sopenharmony_ci{ 98c2ecf20Sopenharmony_ci unsigned long vaddr = (unsigned long)unsafe_src; 108c2ecf20Sopenharmony_ci 118c2ecf20Sopenharmony_ci /* 128c2ecf20Sopenharmony_ci * Do not allow userspace addresses. This disallows 138c2ecf20Sopenharmony_ci * normal userspace and the userspace guard page: 148c2ecf20Sopenharmony_ci */ 158c2ecf20Sopenharmony_ci if (vaddr < TASK_SIZE_MAX + PAGE_SIZE) 168c2ecf20Sopenharmony_ci return false; 178c2ecf20Sopenharmony_ci 188c2ecf20Sopenharmony_ci /* 198c2ecf20Sopenharmony_ci * Allow everything during early boot before 'x86_virt_bits' 208c2ecf20Sopenharmony_ci * is initialized. Needed for instruction decoding in early 218c2ecf20Sopenharmony_ci * exception handlers. 228c2ecf20Sopenharmony_ci */ 238c2ecf20Sopenharmony_ci if (!boot_cpu_data.x86_virt_bits) 248c2ecf20Sopenharmony_ci return true; 258c2ecf20Sopenharmony_ci 268c2ecf20Sopenharmony_ci return __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); 278c2ecf20Sopenharmony_ci} 288c2ecf20Sopenharmony_ci#else 298c2ecf20Sopenharmony_cibool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) 308c2ecf20Sopenharmony_ci{ 318c2ecf20Sopenharmony_ci return (unsigned long)unsafe_src >= TASK_SIZE_MAX; 328c2ecf20Sopenharmony_ci} 338c2ecf20Sopenharmony_ci#endif 34