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
  14         .text
  15         .align  4
  16
  17         /* Read/writer locks, as usual this is overly clever to make it
  18          * as fast as possible.
  19          */
  20
  21         /* caches... */
  22 ___rw_read_enter_spin_on_wlock:
  23         orcc    %g2, 0x0, %g0
  24         be,a    ___rw_read_enter
  25          ldstub [%g1 + 3], %g2
  26         b       ___rw_read_enter_spin_on_wlock
  27          ldub   [%g1 + 3], %g2
  28 ___rw_read_try_spin_on_wlock:
  29         andcc   %g2, 0xff, %g0
  30         be,a    ___rw_read_try
  31          ldstub [%g1 + 3], %g2
  32         xnorcc  %g2, 0x0, %o0   /* if g2 is ~0, set o0 to 0 and bugger off */
  33         bne,a   ___rw_read_enter_spin_on_wlock
  34          ld     [%g1], %g2
  35         retl
  36          mov    %g4, %o7
  37 ___rw_read_exit_spin_on_wlock:
  38         orcc    %g2, 0x0, %g0
  39         be,a    ___rw_read_exit
  40          ldstub [%g1 + 3], %g2
  41         b       ___rw_read_exit_spin_on_wlock
  42          ldub   [%g1 + 3], %g2
  43 ___rw_write_enter_spin_on_wlock:
  44         orcc    %g2, 0x0, %g0
  45         be,a    ___rw_write_enter
  46          ldstub [%g1 + 3], %g2
  47         b       ___rw_write_enter_spin_on_wlock
  48          ld     [%g1], %g2
  49
  50         .globl  ___rw_read_enter
  51 ___rw_read_enter:
  52         orcc    %g2, 0x0, %g0
  53         bne,a   ___rw_read_enter_spin_on_wlock
  54          ldub   [%g1 + 3], %g2
  55         ld      [%g1], %g2
  56         add     %g2, 1, %g2
  57         st      %g2, [%g1]
  58         retl
  59          mov    %g4, %o7
  60
  61         .globl  ___rw_read_exit
  62 ___rw_read_exit:
  63         orcc    %g2, 0x0, %g0
  64         bne,a   ___rw_read_exit_spin_on_wlock
  65          ldub   [%g1 + 3], %g2
  66         ld      [%g1], %g2
  67         sub     %g2, 0x1ff, %g2
  68         st      %g2, [%g1]
  69         retl
  70          mov    %g4, %o7
  71
  72         .globl  ___rw_read_try
  73 ___rw_read_try:
  74         orcc    %g2, 0x0, %g0
  75         bne     ___rw_read_try_spin_on_wlock
  76          ld     [%g1], %g2
  77         add     %g2, 1, %g2
  78         st      %g2, [%g1]
  79         set     1, %o1
  80         retl
  81          mov    %g4, %o7
  82
  83         .globl  ___rw_write_enter
  84 ___rw_write_enter:
  85         orcc    %g2, 0x0, %g0
  86         bne     ___rw_write_enter_spin_on_wlock
  87          ld     [%g1], %g2
  88         andncc  %g2, 0xff, %g0
  89         bne,a   ___rw_write_enter_spin_on_wlock
  90          stb    %g0, [%g1 + 3]
  91         retl
  92          mov    %g4, %o7