1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * User address space access functions. 4 * 5 * Copyright 1997 Andi Kleen <ak@muc.de> 6 * Copyright 1997 Linus Torvalds 7 * Copyright 2002 Andi Kleen <ak@suse.de> 8 */ 9 #include <linux/export.h> 10 #include <linux/uaccess.h> 11 #include <linux/highmem.h> 12 13 /* 14 * Zero Userspace 15 */ 16 17 unsigned long __clear_user(void __user *addr, unsigned long size) 18 { 19 long __d0; 20 might_fault(); 21 /* no memory constraint because it doesn't change any memory gcc knows 22 about */ 23 stac(); 24 asm volatile( 25 " testq %[size8],%[size8]\n" 26 " jz 4f\n" 27 "0: movq $0,(%[dst])\n" 28 " addq $8,%[dst]\n" 29 " decl %%ecx ; jnz 0b\n" 30 "4: movq %[size1],%%rcx\n" 31 " testl %%ecx,%%ecx\n" 32 " jz 2f\n" 33 "1: movb $0,(%[dst])\n" 34 " incq %[dst]\n" 35 " decl %%ecx ; jnz 1b\n" 36 "2:\n" 37 ".section .fixup,\"ax\"\n" 38 "3: lea 0(%[size1],%[size8],8),%[size8]\n" 39 " jmp 2b\n" 40 ".previous\n" 41 _ASM_EXTABLE_UA(0b, 3b) 42 _ASM_EXTABLE_UA(1b, 2b) 43 : [size8] "=&c"(size), [dst] "=&D" (__d0) 44 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr)); 45 clac(); 46 return size; 47 } 48 EXPORT_SYMBOL(__clear_user); 49 50 unsigned long clear_user(void __user *to, unsigned long n) 51 { 52 if (access_ok(to, n)) 53 return __clear_user(to, n); 54 return n; 55 } 56 EXPORT_SYMBOL(clear_user); 57 58 /* 59 * Similar to copy_user_handle_tail, probe for the write fault point, 60 * but reuse __memcpy_mcsafe in case a new read error is encountered. 61 * clac() is handled in _copy_to_iter_mcsafe(). 62 */ 63 __visible unsigned long 64 mcsafe_handle_tail(char *to, char *from, unsigned len) 65 { 66 for (; len; --len, to++, from++) { 67 /* 68 * Call the assembly routine back directly since 69 * memcpy_mcsafe() may silently fallback to memcpy. 70 */ 71 unsigned long rem = __memcpy_mcsafe(to, from, 1); 72 73 if (rem) 74 break; 75 } 76 return len; 77 } 78 79 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 80 /** 81 * clean_cache_range - write back a cache range with CLWB 82 * @vaddr: virtual start address 83 * @size: number of bytes to write back 84 * 85 * Write back a cache range using the CLWB (cache line write back) 86 * instruction. Note that @size is internally rounded up to be cache 87 * line size aligned. 88 */ 89 static void clean_cache_range(void *addr, size_t size) 90 { 91 u16 x86_clflush_size = boot_cpu_data.x86_clflush_size; 92 unsigned long clflush_mask = x86_clflush_size - 1; 93 void *vend = addr + size; 94 void *p; 95 96 for (p = (void *)((unsigned long)addr & ~clflush_mask); 97 p < vend; p += x86_clflush_size) 98 clwb(p); 99 } 100 101 void arch_wb_cache_pmem(void *addr, size_t size) 102 { 103 clean_cache_range(addr, size); 104 } 105 EXPORT_SYMBOL_GPL(arch_wb_cache_pmem); 106 107 long __copy_user_flushcache(void *dst, const void __user *src, unsigned size) 108 { 109 unsigned long flushed, dest = (unsigned long) dst; 110 long rc = __copy_user_nocache(dst, src, size, 0); 111 112 /* 113 * __copy_user_nocache() uses non-temporal stores for the bulk 114 * of the transfer, but we need to manually flush if the 115 * transfer is unaligned. A cached memory copy is used when 116 * destination or size is not naturally aligned. That is: 117 * - Require 8-byte alignment when size is 8 bytes or larger. 118 * - Require 4-byte alignment when size is 4 bytes. 119 */ 120 if (size < 8) { 121 if (!IS_ALIGNED(dest, 4) || size != 4) 122 clean_cache_range(dst, 1); 123 } else { 124 if (!IS_ALIGNED(dest, 8)) { 125 dest = ALIGN(dest, boot_cpu_data.x86_clflush_size); 126 clean_cache_range(dst, 1); 127 } 128 129 flushed = dest - (unsigned long) dst; 130 if (size > flushed && !IS_ALIGNED(size - flushed, 8)) 131 clean_cache_range(dst + size - 1, 1); 132 } 133 134 return rc; 135 } 136 137 void __memcpy_flushcache(void *_dst, const void *_src, size_t size) 138 { 139 unsigned long dest = (unsigned long) _dst; 140 unsigned long source = (unsigned long) _src; 141 142 /* cache copy and flush to align dest */ 143 if (!IS_ALIGNED(dest, 8)) { 144 unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest); 145 146 memcpy((void *) dest, (void *) source, len); 147 clean_cache_range((void *) dest, len); 148 dest += len; 149 source += len; 150 size -= len; 151 if (!size) 152 return; 153 } 154 155 /* 4x8 movnti loop */ 156 while (size >= 32) { 157 asm("movq (%0), %%r8\n" 158 "movq 8(%0), %%r9\n" 159 "movq 16(%0), %%r10\n" 160 "movq 24(%0), %%r11\n" 161 "movnti %%r8, (%1)\n" 162 "movnti %%r9, 8(%1)\n" 163 "movnti %%r10, 16(%1)\n" 164 "movnti %%r11, 24(%1)\n" 165 :: "r" (source), "r" (dest) 166 : "memory", "r8", "r9", "r10", "r11"); 167 dest += 32; 168 source += 32; 169 size -= 32; 170 } 171 172 /* 1x8 movnti loop */ 173 while (size >= 8) { 174 asm("movq (%0), %%r8\n" 175 "movnti %%r8, (%1)\n" 176 :: "r" (source), "r" (dest) 177 : "memory", "r8"); 178 dest += 8; 179 source += 8; 180 size -= 8; 181 } 182 183 /* 1x4 movnti loop */ 184 while (size >= 4) { 185 asm("movl (%0), %%r8d\n" 186 "movnti %%r8d, (%1)\n" 187 :: "r" (source), "r" (dest) 188 : "memory", "r8"); 189 dest += 4; 190 source += 4; 191 size -= 4; 192 } 193 194 /* cache copy for remaining bytes */ 195 if (size) { 196 memcpy((void *) dest, (void *) source, size); 197 clean_cache_range((void *) dest, size); 198 } 199 } 200 EXPORT_SYMBOL_GPL(__memcpy_flushcache); 201 202 void memcpy_page_flushcache(char *to, struct page *page, size_t offset, 203 size_t len) 204 { 205 char *from = kmap_atomic(page); 206 207 memcpy_flushcache(to, from + offset, len); 208 kunmap_atomic(from); 209 } 210 #endif 211