arch/tile/lib/usercopy_32.S

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #include <linux/linkage.h>
  16 #include <asm/errno.h>
  17 #include <asm/cache.h>
  18 #include <arch/chip.h>
  19
  20 /* Access user memory, but use MMU to avoid propagating kernel exceptions. */
  21
  22 /*
  23  * strnlen_user_asm takes the pointer in r0, and the length bound in r1.
  24  * It returns the length, including the terminating NUL, or zero on exception.
  25  * If length is greater than the bound, returns one plus the bound.
  26  */
  27 STD_ENTRY(strnlen_user_asm)
  28         { bz r1, 2f; addi r3, r0, -1 }  /* bias down to include NUL */
  29 1:      { lb_u r4, r0; addi r1, r1, -1 }
  30         bz r4, 2f
  31         { bnzt r1, 1b; addi r0, r0, 1 }
  32 2:      { sub r0, r0, r3; jrp lr }
  33         STD_ENDPROC(strnlen_user_asm)
  34         .pushsection .fixup,"ax"
  35 strnlen_user_fault:
  36         { move r0, zero; jrp lr }
  37         ENDPROC(strnlen_user_fault)
  38         .section __ex_table,"a"
  39         .align 4
  40         .word 1b, strnlen_user_fault
  41         .popsection
  42
  43 /*
  44  * strncpy_from_user_asm takes the kernel target pointer in r0,
  45  * the userspace source pointer in r1, and the length bound (including
  46  * the trailing NUL) in r2.  On success, it returns the string length
  47  * (not including the trailing NUL), or -EFAULT on failure.
  48  */
  49 STD_ENTRY(strncpy_from_user_asm)
  50         { bz r2, 2f; move r3, r0 }
  51 1:      { lb_u r4, r1; addi r1, r1, 1; addi r2, r2, -1 }
  52         { sb r0, r4; addi r0, r0, 1 }
  53         bz r4, 2f
  54         bnzt r2, 1b
  55         { sub r0, r0, r3; jrp lr }
  56 2:      addi r0, r0, -1   /* don't count the trailing NUL */
  57         { sub r0, r0, r3; jrp lr }
  58         STD_ENDPROC(strncpy_from_user_asm)
  59         .pushsection .fixup,"ax"
  60 strncpy_from_user_fault:
  61         { movei r0, -EFAULT; jrp lr }
  62         ENDPROC(strncpy_from_user_fault)
  63         .section __ex_table,"a"
  64         .align 4
  65         .word 1b, strncpy_from_user_fault
  66         .popsection
  67
  68 /*
  69  * clear_user_asm takes the user target address in r0 and the
  70  * number of bytes to zero in r1.
  71  * It returns the number of uncopiable bytes (hopefully zero) in r0.
  72  * Note that we don't use a separate .fixup section here since we fall
  73  * through into the "fixup" code as the last straight-line bundle anyway.
  74  */
  75 STD_ENTRY(clear_user_asm)
  76         { bz r1, 2f; or r2, r0, r1 }
  77         andi r2, r2, 3
  78         bzt r2, .Lclear_aligned_user_asm
  79 1:      { sb r0, zero; addi r0, r0, 1; addi r1, r1, -1 }
  80         bnzt r1, 1b
  81 2:      { move r0, r1; jrp lr }
  82         .pushsection __ex_table,"a"
  83         .align 4
  84         .word 1b, 2b
  85         .popsection
  86
  87 .Lclear_aligned_user_asm:
  88 1:      { sw r0, zero; addi r0, r0, 4; addi r1, r1, -4 }
  89         bnzt r1, 1b
  90 2:      { move r0, r1; jrp lr }
  91         STD_ENDPROC(clear_user_asm)
  92         .pushsection __ex_table,"a"
  93         .align 4
  94         .word 1b, 2b
  95         .popsection
  96
  97 /*
  98  * flush_user_asm takes the user target address in r0 and the
  99  * number of bytes to flush in r1.
 100  * It returns the number of unflushable bytes (hopefully zero) in r0.
 101  */
 102 STD_ENTRY(flush_user_asm)
 103         bz r1, 2f
 104         { movei r2, L2_CACHE_BYTES; add r1, r0, r1 }
 105         { sub r2, zero, r2; addi r1, r1, L2_CACHE_BYTES-1 }
 106         { and r0, r0, r2; and r1, r1, r2 }
 107         { sub r1, r1, r0 }
 108 1:      { flush r0; addi r1, r1, -CHIP_FLUSH_STRIDE() }
 109         { addi r0, r0, CHIP_FLUSH_STRIDE(); bnzt r1, 1b }
 110 2:      { move r0, r1; jrp lr }
 111         STD_ENDPROC(flush_user_asm)
 112         .pushsection __ex_table,"a"
 113         .align 4
 114         .word 1b, 2b
 115         .popsection
 116
 117 /*
 118  * finv_user_asm takes the user target address in r0 and the
 119  * number of bytes to flush-invalidate in r1.
 120  * It returns the number of not finv'able bytes (hopefully zero) in r0.
 121  */
 122 STD_ENTRY(finv_user_asm)
 123         bz r1, 2f
 124         { movei r2, L2_CACHE_BYTES; add r1, r0, r1 }
 125         { sub r2, zero, r2; addi r1, r1, L2_CACHE_BYTES-1 }
 126         { and r0, r0, r2; and r1, r1, r2 }
 127         { sub r1, r1, r0 }
 128 1:      { finv r0; addi r1, r1, -CHIP_FINV_STRIDE() }
 129         { addi r0, r0, CHIP_FINV_STRIDE(); bnzt r1, 1b }
 130 2:      { move r0, r1; jrp lr }
 131         STD_ENDPROC(finv_user_asm)
 132         .pushsection __ex_table,"a"
 133         .align 4
 134         .word 1b, 2b
 135         .popsection