arch/x86/lib/copy_user_nocache_64.S

   1 /* Copyright 2002 Andi Kleen, SuSE Labs.
   2  * Subject to the GNU Public License v2.
   3  *
   4  * Functions to copy from and to user space.
   5  */
   6
   7 #include <linux/linkage.h>
   8 #include <asm/dwarf2.h>
   9
  10 #define FIX_ALIGNMENT 1
  11
  12 #include <asm/current.h>
  13 #include <asm/asm-offsets.h>
  14 #include <asm/thread_info.h>
  15 #include <asm/cpufeature.h>
  16
  17 /*
  18  * copy_user_nocache - Uncached memory copy with exception handling
  19  * This will force destination/source out of cache for more performance.
  20  *
  21  * Input:
  22  * rdi destination
  23  * rsi source
  24  * rdx count
  25  * rcx zero flag        when 1 zero on exception
  26  *
  27  * Output:
  28  * eax uncopied bytes or 0 if successful.
  29  */
  30 ENTRY(__copy_user_nocache)
  31         CFI_STARTPROC
  32         pushq %rbx
  33         CFI_ADJUST_CFA_OFFSET 8
  34         CFI_REL_OFFSET rbx, 0
  35         pushq %rcx              /* save zero flag */
  36         CFI_ADJUST_CFA_OFFSET 8
  37         CFI_REL_OFFSET rcx, 0
  38
  39         xorl %eax,%eax          /* zero for the exception handler */
  40
  41 #ifdef FIX_ALIGNMENT
  42         /* check for bad alignment of destination */
  43         movl %edi,%ecx
  44         andl $7,%ecx
  45         jnz  .Lbad_alignment
  46 .Lafter_bad_alignment:
  47 #endif
  48
  49         movq %rdx,%rcx
  50
  51         movl $64,%ebx
  52         shrq $6,%rdx
  53         decq %rdx
  54         js   .Lhandle_tail
  55
  56         .p2align 4
  57 .Lloop:
  58 .Ls1:   movq (%rsi),%r11
  59 .Ls2:   movq 1*8(%rsi),%r8
  60 .Ls3:   movq 2*8(%rsi),%r9
  61 .Ls4:   movq 3*8(%rsi),%r10
  62 .Ld1:   movnti %r11,(%rdi)
  63 .Ld2:   movnti %r8,1*8(%rdi)
  64 .Ld3:   movnti %r9,2*8(%rdi)
  65 .Ld4:   movnti %r10,3*8(%rdi)
  66
  67 .Ls5:   movq 4*8(%rsi),%r11
  68 .Ls6:   movq 5*8(%rsi),%r8
  69 .Ls7:   movq 6*8(%rsi),%r9
  70 .Ls8:   movq 7*8(%rsi),%r10
  71 .Ld5:   movnti %r11,4*8(%rdi)
  72 .Ld6:   movnti %r8,5*8(%rdi)
  73 .Ld7:   movnti %r9,6*8(%rdi)
  74 .Ld8:   movnti %r10,7*8(%rdi)
  75
  76         dec  %rdx
  77
  78         leaq 64(%rsi),%rsi
  79         leaq 64(%rdi),%rdi
  80
  81         jns  .Lloop
  82
  83         .p2align 4
  84 .Lhandle_tail:
  85         movl %ecx,%edx
  86         andl $63,%ecx
  87         shrl $3,%ecx
  88         jz   .Lhandle_7
  89         movl $8,%ebx
  90         .p2align 4
  91 .Lloop_8:
  92 .Ls9:   movq (%rsi),%r8
  93 .Ld9:   movnti %r8,(%rdi)
  94         decl %ecx
  95         leaq 8(%rdi),%rdi
  96         leaq 8(%rsi),%rsi
  97         jnz .Lloop_8
  98
  99 .Lhandle_7:
 100         movl %edx,%ecx
 101         andl $7,%ecx
 102         jz   .Lende
 103         .p2align 4
 104 .Lloop_1:
 105 .Ls10:  movb (%rsi),%bl
 106 .Ld10:  movb %bl,(%rdi)
 107         incq %rdi
 108         incq %rsi
 109         decl %ecx
 110         jnz .Lloop_1
 111
 112         CFI_REMEMBER_STATE
 113 .Lende:
 114         popq %rcx
 115         CFI_ADJUST_CFA_OFFSET -8
 116         CFI_RESTORE %rcx
 117         popq %rbx
 118         CFI_ADJUST_CFA_OFFSET -8
 119         CFI_RESTORE rbx
 120         ret
 121         CFI_RESTORE_STATE
 122
 123 #ifdef FIX_ALIGNMENT
 124         /* align destination */
 125         .p2align 4
 126 .Lbad_alignment:
 127         movl $8,%r9d
 128         subl %ecx,%r9d
 129         movl %r9d,%ecx
 130         cmpq %r9,%rdx
 131         jz   .Lhandle_7
 132         js   .Lhandle_7
 133 .Lalign_1:
 134 .Ls11:  movb (%rsi),%bl
 135 .Ld11:  movb %bl,(%rdi)
 136         incq %rsi
 137         incq %rdi
 138         decl %ecx
 139         jnz .Lalign_1
 140         subq %r9,%rdx
 141         jmp .Lafter_bad_alignment
 142 #endif
 143
 144         /* table sorted by exception address */
 145         .section __ex_table,"a"
 146         .align 8
 147         .quad .Ls1,.Ls1e
 148         .quad .Ls2,.Ls2e
 149         .quad .Ls3,.Ls3e
 150         .quad .Ls4,.Ls4e
 151         .quad .Ld1,.Ls1e
 152         .quad .Ld2,.Ls2e
 153         .quad .Ld3,.Ls3e
 154         .quad .Ld4,.Ls4e
 155         .quad .Ls5,.Ls5e
 156         .quad .Ls6,.Ls6e
 157         .quad .Ls7,.Ls7e
 158         .quad .Ls8,.Ls8e
 159         .quad .Ld5,.Ls5e
 160         .quad .Ld6,.Ls6e
 161         .quad .Ld7,.Ls7e
 162         .quad .Ld8,.Ls8e
 163         .quad .Ls9,.Le_quad
 164         .quad .Ld9,.Le_quad
 165         .quad .Ls10,.Le_byte
 166         .quad .Ld10,.Le_byte
 167 #ifdef FIX_ALIGNMENT
 168         .quad .Ls11,.Lzero_rest
 169         .quad .Ld11,.Lzero_rest
 170 #endif
 171         .quad .Le5,.Le_zero
 172         .previous
 173
 174         /* compute 64-offset for main loop. 8 bytes accuracy with error on the
 175            pessimistic side. this is gross. it would be better to fix the
 176            interface. */
 177         /* eax: zero, ebx: 64 */
 178 .Ls1e:  addl $8,%eax
 179 .Ls2e:  addl $8,%eax
 180 .Ls3e:  addl $8,%eax
 181 .Ls4e:  addl $8,%eax
 182 .Ls5e:  addl $8,%eax
 183 .Ls6e:  addl $8,%eax
 184 .Ls7e:  addl $8,%eax
 185 .Ls8e:  addl $8,%eax
 186         addq %rbx,%rdi  /* +64 */
 187         subq %rax,%rdi  /* correct destination with computed offset */
 188
 189         shlq $6,%rdx    /* loop counter * 64 (stride length) */
 190         addq %rax,%rdx  /* add offset to loopcnt */
 191         andl $63,%ecx   /* remaining bytes */
 192         addq %rcx,%rdx  /* add them */
 193         jmp .Lzero_rest
 194
 195         /* exception on quad word loop in tail handling */
 196         /* ecx: loopcnt/8, %edx: length, rdi: correct */
 197 .Le_quad:
 198         shll $3,%ecx
 199         andl $7,%edx
 200         addl %ecx,%edx
 201         /* edx: bytes to zero, rdi: dest, eax:zero */
 202 .Lzero_rest:
 203         cmpl $0,(%rsp)  /* zero flag set? */
 204         jz   .Le_zero
 205         movq %rdx,%rcx
 206 .Le_byte:
 207         xorl %eax,%eax
 208 .Le5:   rep
 209         stosb
 210         /* when there is another exception while zeroing the rest just return */
 211 .Le_zero:
 212         movq %rdx,%rax
 213         jmp .Lende
 214         CFI_ENDPROC
 215 ENDPROC(__copy_user_nocache)
 216
 217