xref: /OK3568_Linux_fs/kernel/arch/x86/mm/maccess.c (revision 4882a59341e53eb6f0b4789bf948001014eff981) 
1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun 
3*4882a593Smuzhiyun #include <linux/uaccess.h>
4*4882a593Smuzhiyun #include <linux/kernel.h>
5*4882a593Smuzhiyun 
6*4882a593Smuzhiyun #ifdef CONFIG_X86_64
canonical_address(u64 vaddr,u8 vaddr_bits)7*4882a593Smuzhiyun static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)
8*4882a593Smuzhiyun {
9*4882a593Smuzhiyun 	return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
10*4882a593Smuzhiyun }
11*4882a593Smuzhiyun 
copy_from_kernel_nofault_allowed(const void * unsafe_src,size_t size)12*4882a593Smuzhiyun bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
13*4882a593Smuzhiyun {
14*4882a593Smuzhiyun 	unsigned long vaddr = (unsigned long)unsafe_src;
15*4882a593Smuzhiyun 
16*4882a593Smuzhiyun 	/*
17*4882a593Smuzhiyun 	 * Range covering the highest possible canonical userspace address
18*4882a593Smuzhiyun 	 * as well as non-canonical address range. For the canonical range
19*4882a593Smuzhiyun 	 * we also need to include the userspace guard page.
20*4882a593Smuzhiyun 	 */
21*4882a593Smuzhiyun 	return vaddr >= TASK_SIZE_MAX + PAGE_SIZE &&
22*4882a593Smuzhiyun 	       canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr;
23*4882a593Smuzhiyun }
24*4882a593Smuzhiyun #else
copy_from_kernel_nofault_allowed(const void * unsafe_src,size_t size)25*4882a593Smuzhiyun bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun 	return (unsigned long)unsafe_src >= TASK_SIZE_MAX;
28*4882a593Smuzhiyun }
29*4882a593Smuzhiyun #endif
30