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 static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits) 8 { 9 return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits); 10 } 11 12 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) 13 { 14 unsigned long vaddr = (unsigned long)unsafe_src; 15 16 /* 17 * Range covering the highest possible canonical userspace address 18 * as well as non-canonical address range. For the canonical range 19 * we also need to include the userspace guard page. 20 */ 21 return vaddr >= TASK_SIZE_MAX + PAGE_SIZE && 22 canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr; 23 } 24 #else 25 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) 26 { 27 return (unsigned long)unsafe_src >= TASK_SIZE_MAX; 28 } 29 #endif 30