arch/sparc/lib/locks.S

   1 /*
   2  * locks.S: SMP low-level lock primitives on Sparc.
   3  *
   4  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   5  * Copyright (C) 1998 Anton Blanchard (anton@progsoc.uts.edu.au)
   6  * Copyright (C) 1998 Jakub Jelinek   (jj@ultra.linux.cz)
   7  */
   8
   9 #include <asm/ptrace.h>
  10 #include <asm/psr.h>
  11 #include <asm/smp.h>
  12 #include <asm/spinlock.h>
  13 #include <asm/export.h>
  14
  15         .text
  16         .align  4
  17
  18         /* Read/writer locks, as usual this is overly clever to make it
  19          * as fast as possible.
  20          */
  21
  22         /* caches... */
  23 ___rw_read_enter_spin_on_wlock:
  24         orcc    %g2, 0x0, %g0
  25         be,a    ___rw_read_enter
  26          ldstub [%g1 + 3], %g2
  27         b       ___rw_read_enter_spin_on_wlock
  28          ldub   [%g1 + 3], %g2
  29 ___rw_read_try_spin_on_wlock:
  30         andcc   %g2, 0xff, %g0
  31         be,a    ___rw_read_try
  32          ldstub [%g1 + 3], %g2
  33         xnorcc  %g2, 0x0, %o0   /* if g2 is ~0, set o0 to 0 and bugger off */
  34         bne,a   ___rw_read_enter_spin_on_wlock
  35          ld     [%g1], %g2
  36         retl
  37          mov    %g4, %o7
  38 ___rw_read_exit_spin_on_wlock:
  39         orcc    %g2, 0x0, %g0
  40         be,a    ___rw_read_exit
  41          ldstub [%g1 + 3], %g2
  42         b       ___rw_read_exit_spin_on_wlock
  43          ldub   [%g1 + 3], %g2
  44 ___rw_write_enter_spin_on_wlock:
  45         orcc    %g2, 0x0, %g0
  46         be,a    ___rw_write_enter
  47          ldstub [%g1 + 3], %g2
  48         b       ___rw_write_enter_spin_on_wlock
  49          ld     [%g1], %g2
  50
  51         .globl  ___rw_read_enter
  52 EXPORT_SYMBOL(___rw_read_enter)
  53 ___rw_read_enter:
  54         orcc    %g2, 0x0, %g0
  55         bne,a   ___rw_read_enter_spin_on_wlock
  56          ldub   [%g1 + 3], %g2
  57         ld      [%g1], %g2
  58         add     %g2, 1, %g2
  59         st      %g2, [%g1]
  60         retl
  61          mov    %g4, %o7
  62
  63         .globl  ___rw_read_exit
  64 EXPORT_SYMBOL(___rw_read_exit)
  65 ___rw_read_exit:
  66         orcc    %g2, 0x0, %g0
  67         bne,a   ___rw_read_exit_spin_on_wlock
  68          ldub   [%g1 + 3], %g2
  69         ld      [%g1], %g2
  70         sub     %g2, 0x1ff, %g2
  71         st      %g2, [%g1]
  72         retl
  73          mov    %g4, %o7
  74
  75         .globl  ___rw_read_try
  76 EXPORT_SYMBOL(___rw_read_try)
  77 ___rw_read_try:
  78         orcc    %g2, 0x0, %g0
  79         bne     ___rw_read_try_spin_on_wlock
  80          ld     [%g1], %g2
  81         add     %g2, 1, %g2
  82         st      %g2, [%g1]
  83         set     1, %o1
  84         retl
  85          mov    %g4, %o7
  86
  87         .globl  ___rw_write_enter
  88 EXPORT_SYMBOL(___rw_write_enter)
  89 ___rw_write_enter:
  90         orcc    %g2, 0x0, %g0
  91         bne     ___rw_write_enter_spin_on_wlock
  92          ld     [%g1], %g2
  93         andncc  %g2, 0xff, %g0
  94         bne,a   ___rw_write_enter_spin_on_wlock
  95          stb    %g0, [%g1 + 3]
  96         retl
  97          mov    %g4, %o7