root/arch/sparc/lib/locks.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * locks.S: SMP low-level lock primitives on Sparc.
   4  *
   5  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   6  * Copyright (C) 1998 Anton Blanchard (anton@progsoc.uts.edu.au)
   7  * Copyright (C) 1998 Jakub Jelinek   (jj@ultra.linux.cz)
   8  */
   9 
  10 #include <asm/ptrace.h>
  11 #include <asm/psr.h>
  12 #include <asm/smp.h>
  13 #include <asm/spinlock.h>
  14 #include <asm/export.h>
  15 
  16         .text
  17         .align  4
  18 
  19         /* Read/writer locks, as usual this is overly clever to make it
  20          * as fast as possible.
  21          */
  22 
  23         /* caches... */
  24 ___rw_read_enter_spin_on_wlock:
  25         orcc    %g2, 0x0, %g0
  26         be,a    ___rw_read_enter
  27          ldstub [%g1 + 3], %g2
  28         b       ___rw_read_enter_spin_on_wlock
  29          ldub   [%g1 + 3], %g2
  30 ___rw_read_try_spin_on_wlock:
  31         andcc   %g2, 0xff, %g0
  32         be,a    ___rw_read_try
  33          ldstub [%g1 + 3], %g2
  34         xnorcc  %g2, 0x0, %o0   /* if g2 is ~0, set o0 to 0 and bugger off */
  35         bne,a   ___rw_read_enter_spin_on_wlock
  36          ld     [%g1], %g2
  37         retl
  38          mov    %g4, %o7
  39 ___rw_read_exit_spin_on_wlock:
  40         orcc    %g2, 0x0, %g0
  41         be,a    ___rw_read_exit
  42          ldstub [%g1 + 3], %g2
  43         b       ___rw_read_exit_spin_on_wlock
  44          ldub   [%g1 + 3], %g2
  45 ___rw_write_enter_spin_on_wlock:
  46         orcc    %g2, 0x0, %g0
  47         be,a    ___rw_write_enter
  48          ldstub [%g1 + 3], %g2
  49         b       ___rw_write_enter_spin_on_wlock
  50          ld     [%g1], %g2
  51 
  52         .globl  ___rw_read_enter
  53 EXPORT_SYMBOL(___rw_read_enter)
  54 ___rw_read_enter:
  55         orcc    %g2, 0x0, %g0
  56         bne,a   ___rw_read_enter_spin_on_wlock
  57          ldub   [%g1 + 3], %g2
  58         ld      [%g1], %g2
  59         add     %g2, 1, %g2
  60         st      %g2, [%g1]
  61         retl
  62          mov    %g4, %o7
  63 
  64         .globl  ___rw_read_exit
  65 EXPORT_SYMBOL(___rw_read_exit)
  66 ___rw_read_exit:
  67         orcc    %g2, 0x0, %g0
  68         bne,a   ___rw_read_exit_spin_on_wlock
  69          ldub   [%g1 + 3], %g2
  70         ld      [%g1], %g2
  71         sub     %g2, 0x1ff, %g2
  72         st      %g2, [%g1]
  73         retl
  74          mov    %g4, %o7
  75 
  76         .globl  ___rw_read_try
  77 EXPORT_SYMBOL(___rw_read_try)
  78 ___rw_read_try:
  79         orcc    %g2, 0x0, %g0
  80         bne     ___rw_read_try_spin_on_wlock
  81          ld     [%g1], %g2
  82         add     %g2, 1, %g2
  83         st      %g2, [%g1]
  84         set     1, %o1
  85         retl
  86          mov    %g4, %o7
  87 
  88         .globl  ___rw_write_enter
  89 EXPORT_SYMBOL(___rw_write_enter)
  90 ___rw_write_enter:
  91         orcc    %g2, 0x0, %g0
  92         bne     ___rw_write_enter_spin_on_wlock
  93          ld     [%g1], %g2
  94         andncc  %g2, 0xff, %g0
  95         bne,a   ___rw_write_enter_spin_on_wlock
  96          stb    %g0, [%g1 + 3]
  97         retl
  98          mov    %g4, %o7