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 39 _ASM_EXTABLE_TYPE_REG(0b, 2b, EX_TYPE_UCOPY_LEN8, %[size1]) 40 _ASM_EXTABLE_UA(1b, 2b) 41 42 : [size8] "=&c"(size), [dst] "=&D" (__d0) 43 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr)); 44 clac(); 45 return size; 46 } 47 EXPORT_SYMBOL(__clear_user); 48 49 unsigned long clear_user(void __user *to, unsigned long n) 50 { 51 if (access_ok(to, n)) 52 return __clear_user(to, n); 53 return n; 54 } 55 EXPORT_SYMBOL(clear_user); 56 57 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 58 /** 59 * clean_cache_range - write back a cache range with CLWB 60 * @vaddr: virtual start address 61 * @size: number of bytes to write back 62 * 63 * Write back a cache range using the CLWB (cache line write back) 64 * instruction. Note that @size is internally rounded up to be cache 65 * line size aligned. 66 */ 67 static void clean_cache_range(void *addr, size_t size) 68 { 69 u16 x86_clflush_size = boot_cpu_data.x86_clflush_size; 70 unsigned long clflush_mask = x86_clflush_size - 1; 71 void *vend = addr + size; 72 void *p; 73 74 for (p = (void *)((unsigned long)addr & ~clflush_mask); 75 p < vend; p += x86_clflush_size) 76 clwb(p); 77 } 78 79 void arch_wb_cache_pmem(void *addr, size_t size) 80 { 81 clean_cache_range(addr, size); 82 } 83 EXPORT_SYMBOL_GPL(arch_wb_cache_pmem); 84 85 long __copy_user_flushcache(void *dst, const void __user *src, unsigned size) 86 { 87 unsigned long flushed, dest = (unsigned long) dst; 88 long rc = __copy_user_nocache(dst, src, size, 0); 89 90 /* 91 * __copy_user_nocache() uses non-temporal stores for the bulk 92 * of the transfer, but we need to manually flush if the 93 * transfer is unaligned. A cached memory copy is used when 94 * destination or size is not naturally aligned. That is: 95 * - Require 8-byte alignment when size is 8 bytes or larger. 96 * - Require 4-byte alignment when size is 4 bytes. 97 */ 98 if (size < 8) { 99 if (!IS_ALIGNED(dest, 4) || size != 4) 100 clean_cache_range(dst, size); 101 } else { 102 if (!IS_ALIGNED(dest, 8)) { 103 dest = ALIGN(dest, boot_cpu_data.x86_clflush_size); 104 clean_cache_range(dst, 1); 105 } 106 107 flushed = dest - (unsigned long) dst; 108 if (size > flushed && !IS_ALIGNED(size - flushed, 8)) 109 clean_cache_range(dst + size - 1, 1); 110 } 111 112 return rc; 113 } 114 115 void __memcpy_flushcache(void *_dst, const void *_src, size_t size) 116 { 117 unsigned long dest = (unsigned long) _dst; 118 unsigned long source = (unsigned long) _src; 119 120 /* cache copy and flush to align dest */ 121 if (!IS_ALIGNED(dest, 8)) { 122 size_t len = min_t(size_t, size, ALIGN(dest, 8) - dest); 123 124 memcpy((void *) dest, (void *) source, len); 125 clean_cache_range((void *) dest, len); 126 dest += len; 127 source += len; 128 size -= len; 129 if (!size) 130 return; 131 } 132 133 /* 4x8 movnti loop */ 134 while (size >= 32) { 135 asm("movq (%0), %%r8\n" 136 "movq 8(%0), %%r9\n" 137 "movq 16(%0), %%r10\n" 138 "movq 24(%0), %%r11\n" 139 "movnti %%r8, (%1)\n" 140 "movnti %%r9, 8(%1)\n" 141 "movnti %%r10, 16(%1)\n" 142 "movnti %%r11, 24(%1)\n" 143 :: "r" (source), "r" (dest) 144 : "memory", "r8", "r9", "r10", "r11"); 145 dest += 32; 146 source += 32; 147 size -= 32; 148 } 149 150 /* 1x8 movnti loop */ 151 while (size >= 8) { 152 asm("movq (%0), %%r8\n" 153 "movnti %%r8, (%1)\n" 154 :: "r" (source), "r" (dest) 155 : "memory", "r8"); 156 dest += 8; 157 source += 8; 158 size -= 8; 159 } 160 161 /* 1x4 movnti loop */ 162 while (size >= 4) { 163 asm("movl (%0), %%r8d\n" 164 "movnti %%r8d, (%1)\n" 165 :: "r" (source), "r" (dest) 166 : "memory", "r8"); 167 dest += 4; 168 source += 4; 169 size -= 4; 170 } 171 172 /* cache copy for remaining bytes */ 173 if (size) { 174 memcpy((void *) dest, (void *) source, size); 175 clean_cache_range((void *) dest, size); 176 } 177 } 178 EXPORT_SYMBOL_GPL(__memcpy_flushcache); 179 180 void memcpy_page_flushcache(char *to, struct page *page, size_t offset, 181 size_t len) 182 { 183 char *from = kmap_atomic(page); 184 185 memcpy_flushcache(to, from + offset, len); 186 kunmap_atomic(from); 187 } 188 #endif 189