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 " .align 16\n" 28 "0: movq $0,(%[dst])\n" 29 " addq $8,%[dst]\n" 30 " decl %%ecx ; jnz 0b\n" 31 "4: movq %[size1],%%rcx\n" 32 " testl %%ecx,%%ecx\n" 33 " jz 2f\n" 34 "1: movb $0,(%[dst])\n" 35 " incq %[dst]\n" 36 " decl %%ecx ; jnz 1b\n" 37 "2:\n" 38 ".section .fixup,\"ax\"\n" 39 "3: lea 0(%[size1],%[size8],8),%[size8]\n" 40 " jmp 2b\n" 41 ".previous\n" 42 _ASM_EXTABLE_UA(0b, 3b) 43 _ASM_EXTABLE_UA(1b, 2b) 44 : [size8] "=&c"(size), [dst] "=&D" (__d0) 45 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr)); 46 clac(); 47 return size; 48 } 49 EXPORT_SYMBOL(__clear_user); 50 51 unsigned long clear_user(void __user *to, unsigned long n) 52 { 53 if (access_ok(to, n)) 54 return __clear_user(to, n); 55 return n; 56 } 57 EXPORT_SYMBOL(clear_user); 58 59 /* 60 * Similar to copy_user_handle_tail, probe for the write fault point, 61 * but reuse __memcpy_mcsafe in case a new read error is encountered. 62 * clac() is handled in _copy_to_iter_mcsafe(). 63 */ 64 __visible notrace unsigned long 65 mcsafe_handle_tail(char *to, char *from, unsigned len) 66 { 67 for (; len; --len, to++, from++) { 68 /* 69 * Call the assembly routine back directly since 70 * memcpy_mcsafe() may silently fallback to memcpy. 71 */ 72 unsigned long rem = __memcpy_mcsafe(to, from, 1); 73 74 if (rem) 75 break; 76 } 77 return len; 78 } 79 80 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 81 /** 82 * clean_cache_range - write back a cache range with CLWB 83 * @vaddr: virtual start address 84 * @size: number of bytes to write back 85 * 86 * Write back a cache range using the CLWB (cache line write back) 87 * instruction. Note that @size is internally rounded up to be cache 88 * line size aligned. 89 */ 90 static void clean_cache_range(void *addr, size_t size) 91 { 92 u16 x86_clflush_size = boot_cpu_data.x86_clflush_size; 93 unsigned long clflush_mask = x86_clflush_size - 1; 94 void *vend = addr + size; 95 void *p; 96 97 for (p = (void *)((unsigned long)addr & ~clflush_mask); 98 p < vend; p += x86_clflush_size) 99 clwb(p); 100 } 101 102 void arch_wb_cache_pmem(void *addr, size_t size) 103 { 104 clean_cache_range(addr, size); 105 } 106 EXPORT_SYMBOL_GPL(arch_wb_cache_pmem); 107 108 long __copy_user_flushcache(void *dst, const void __user *src, unsigned size) 109 { 110 unsigned long flushed, dest = (unsigned long) dst; 111 long rc = __copy_user_nocache(dst, src, size, 0); 112 113 /* 114 * __copy_user_nocache() uses non-temporal stores for the bulk 115 * of the transfer, but we need to manually flush if the 116 * transfer is unaligned. A cached memory copy is used when 117 * destination or size is not naturally aligned. That is: 118 * - Require 8-byte alignment when size is 8 bytes or larger. 119 * - Require 4-byte alignment when size is 4 bytes. 120 */ 121 if (size < 8) { 122 if (!IS_ALIGNED(dest, 4) || size != 4) 123 clean_cache_range(dst, size); 124 } else { 125 if (!IS_ALIGNED(dest, 8)) { 126 dest = ALIGN(dest, boot_cpu_data.x86_clflush_size); 127 clean_cache_range(dst, 1); 128 } 129 130 flushed = dest - (unsigned long) dst; 131 if (size > flushed && !IS_ALIGNED(size - flushed, 8)) 132 clean_cache_range(dst + size - 1, 1); 133 } 134 135 return rc; 136 } 137 138 void __memcpy_flushcache(void *_dst, const void *_src, size_t size) 139 { 140 unsigned long dest = (unsigned long) _dst; 141 unsigned long source = (unsigned long) _src; 142 143 /* cache copy and flush to align dest */ 144 if (!IS_ALIGNED(dest, 8)) { 145 unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest); 146 147 memcpy((void *) dest, (void *) source, len); 148 clean_cache_range((void *) dest, len); 149 dest += len; 150 source += len; 151 size -= len; 152 if (!size) 153 return; 154 } 155 156 /* 4x8 movnti loop */ 157 while (size >= 32) { 158 asm("movq (%0), %%r8\n" 159 "movq 8(%0), %%r9\n" 160 "movq 16(%0), %%r10\n" 161 "movq 24(%0), %%r11\n" 162 "movnti %%r8, (%1)\n" 163 "movnti %%r9, 8(%1)\n" 164 "movnti %%r10, 16(%1)\n" 165 "movnti %%r11, 24(%1)\n" 166 :: "r" (source), "r" (dest) 167 : "memory", "r8", "r9", "r10", "r11"); 168 dest += 32; 169 source += 32; 170 size -= 32; 171 } 172 173 /* 1x8 movnti loop */ 174 while (size >= 8) { 175 asm("movq (%0), %%r8\n" 176 "movnti %%r8, (%1)\n" 177 :: "r" (source), "r" (dest) 178 : "memory", "r8"); 179 dest += 8; 180 source += 8; 181 size -= 8; 182 } 183 184 /* 1x4 movnti loop */ 185 while (size >= 4) { 186 asm("movl (%0), %%r8d\n" 187 "movnti %%r8d, (%1)\n" 188 :: "r" (source), "r" (dest) 189 : "memory", "r8"); 190 dest += 4; 191 source += 4; 192 size -= 4; 193 } 194 195 /* cache copy for remaining bytes */ 196 if (size) { 197 memcpy((void *) dest, (void *) source, size); 198 clean_cache_range((void *) dest, size); 199 } 200 } 201 EXPORT_SYMBOL_GPL(__memcpy_flushcache); 202 203 void memcpy_page_flushcache(char *to, struct page *page, size_t offset, 204 size_t len) 205 { 206 char *from = kmap_atomic(page); 207 208 memcpy_flushcache(to, from + offset, len); 209 kunmap_atomic(from); 210 } 211 #endif 212