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cb8095bba6
In the "xchg" implementation, %ebx and %ecx don't need to be copied
into %eax and %edx respectively (this is only necessary when desiring
to only read the stored value).
In the "add_unless" implementation, swapping the use of %ecx and %esi
for passing arguments allows %esi to become an input only (i.e.
permitting the register to be re-used to address the same object
without reload).
In "{add,sub}_return", doing the initial read64 through the passed in
%ecx decreases a register dependency.
In "inc_not_zero", a branch can be eliminated by or-ing together the
two halves of the current (64-bit) value, and code size can be further
reduced by adjusting the arithmetic slightly.
v2: Undo the folding of "xchg" and "set".
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/4F19A2BC020000780006E0DC@nat28.tlf.novell.com
Cc: Luca Barbieri <luca@luca-barbieri.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
216 lines
3.1 KiB
ArmAsm
216 lines
3.1 KiB
ArmAsm
/*
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* atomic64_t for 586+
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*
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* Copyright © 2010 Luca Barbieri
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/linkage.h>
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#include <asm/alternative-asm.h>
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#include <asm/dwarf2.h>
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.macro SAVE reg
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pushl_cfi %\reg
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CFI_REL_OFFSET \reg, 0
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.endm
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.macro RESTORE reg
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popl_cfi %\reg
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CFI_RESTORE \reg
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.endm
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.macro read64 reg
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movl %ebx, %eax
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movl %ecx, %edx
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/* we need LOCK_PREFIX since otherwise cmpxchg8b always does the write */
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LOCK_PREFIX
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cmpxchg8b (\reg)
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.endm
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ENTRY(atomic64_read_cx8)
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CFI_STARTPROC
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read64 %ecx
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_read_cx8)
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ENTRY(atomic64_set_cx8)
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CFI_STARTPROC
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1:
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/* we don't need LOCK_PREFIX since aligned 64-bit writes
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* are atomic on 586 and newer */
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cmpxchg8b (%esi)
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jne 1b
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_set_cx8)
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ENTRY(atomic64_xchg_cx8)
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CFI_STARTPROC
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1:
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LOCK_PREFIX
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cmpxchg8b (%esi)
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jne 1b
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_xchg_cx8)
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.macro addsub_return func ins insc
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ENTRY(atomic64_\func\()_return_cx8)
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CFI_STARTPROC
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SAVE ebp
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SAVE ebx
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SAVE esi
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SAVE edi
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movl %eax, %esi
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movl %edx, %edi
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movl %ecx, %ebp
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read64 %ecx
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1:
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movl %eax, %ebx
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movl %edx, %ecx
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\ins\()l %esi, %ebx
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\insc\()l %edi, %ecx
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LOCK_PREFIX
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cmpxchg8b (%ebp)
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jne 1b
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10:
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movl %ebx, %eax
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movl %ecx, %edx
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RESTORE edi
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RESTORE esi
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RESTORE ebx
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RESTORE ebp
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_\func\()_return_cx8)
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.endm
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addsub_return add add adc
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addsub_return sub sub sbb
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.macro incdec_return func ins insc
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ENTRY(atomic64_\func\()_return_cx8)
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CFI_STARTPROC
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SAVE ebx
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read64 %esi
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1:
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movl %eax, %ebx
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movl %edx, %ecx
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\ins\()l $1, %ebx
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\insc\()l $0, %ecx
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LOCK_PREFIX
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cmpxchg8b (%esi)
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jne 1b
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10:
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movl %ebx, %eax
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movl %ecx, %edx
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RESTORE ebx
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_\func\()_return_cx8)
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.endm
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incdec_return inc add adc
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incdec_return dec sub sbb
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ENTRY(atomic64_dec_if_positive_cx8)
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CFI_STARTPROC
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SAVE ebx
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read64 %esi
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1:
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movl %eax, %ebx
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movl %edx, %ecx
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subl $1, %ebx
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sbb $0, %ecx
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js 2f
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LOCK_PREFIX
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cmpxchg8b (%esi)
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jne 1b
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2:
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movl %ebx, %eax
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movl %ecx, %edx
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RESTORE ebx
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_dec_if_positive_cx8)
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ENTRY(atomic64_add_unless_cx8)
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CFI_STARTPROC
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SAVE ebp
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SAVE ebx
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/* these just push these two parameters on the stack */
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SAVE edi
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SAVE ecx
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movl %eax, %ebp
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movl %edx, %edi
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read64 %esi
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1:
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cmpl %eax, 0(%esp)
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je 4f
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2:
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movl %eax, %ebx
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movl %edx, %ecx
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addl %ebp, %ebx
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adcl %edi, %ecx
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LOCK_PREFIX
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cmpxchg8b (%esi)
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jne 1b
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movl $1, %eax
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3:
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addl $8, %esp
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CFI_ADJUST_CFA_OFFSET -8
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RESTORE ebx
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RESTORE ebp
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ret
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4:
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cmpl %edx, 4(%esp)
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jne 2b
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xorl %eax, %eax
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jmp 3b
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CFI_ENDPROC
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ENDPROC(atomic64_add_unless_cx8)
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ENTRY(atomic64_inc_not_zero_cx8)
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CFI_STARTPROC
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SAVE ebx
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read64 %esi
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1:
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movl %eax, %ecx
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orl %edx, %ecx
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jz 3f
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movl %eax, %ebx
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xorl %ecx, %ecx
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addl $1, %ebx
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adcl %edx, %ecx
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LOCK_PREFIX
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cmpxchg8b (%esi)
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jne 1b
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movl $1, %eax
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3:
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RESTORE ebx
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ret
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CFI_ENDPROC
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ENDPROC(atomic64_inc_not_zero_cx8)
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