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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>
195 lines
2.6 KiB
ArmAsm
195 lines
2.6 KiB
ArmAsm
/*
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* atomic64_t for 386/486
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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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/* if you want SMP support, implement these with real spinlocks */
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.macro LOCK reg
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pushfl_cfi
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cli
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.endm
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.macro UNLOCK reg
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popfl_cfi
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.endm
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#define BEGIN(op) \
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.macro endp; \
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CFI_ENDPROC; \
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ENDPROC(atomic64_##op##_386); \
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.purgem endp; \
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.endm; \
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ENTRY(atomic64_##op##_386); \
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CFI_STARTPROC; \
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LOCK v;
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#define ENDP endp
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#define RET \
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UNLOCK v; \
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ret
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#define RET_ENDP \
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RET; \
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ENDP
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#define v %ecx
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BEGIN(read)
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movl (v), %eax
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movl 4(v), %edx
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(set)
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movl %ebx, (v)
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movl %ecx, 4(v)
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(xchg)
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movl (v), %eax
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movl 4(v), %edx
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movl %ebx, (v)
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movl %ecx, 4(v)
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RET_ENDP
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#undef v
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#define v %ecx
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BEGIN(add)
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addl %eax, (v)
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adcl %edx, 4(v)
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RET_ENDP
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#undef v
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#define v %ecx
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BEGIN(add_return)
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addl (v), %eax
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adcl 4(v), %edx
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movl %eax, (v)
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movl %edx, 4(v)
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RET_ENDP
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#undef v
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#define v %ecx
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BEGIN(sub)
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subl %eax, (v)
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sbbl %edx, 4(v)
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RET_ENDP
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#undef v
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#define v %ecx
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BEGIN(sub_return)
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negl %edx
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negl %eax
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sbbl $0, %edx
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addl (v), %eax
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adcl 4(v), %edx
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movl %eax, (v)
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movl %edx, 4(v)
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(inc)
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addl $1, (v)
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adcl $0, 4(v)
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(inc_return)
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movl (v), %eax
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movl 4(v), %edx
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addl $1, %eax
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adcl $0, %edx
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movl %eax, (v)
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movl %edx, 4(v)
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(dec)
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subl $1, (v)
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sbbl $0, 4(v)
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(dec_return)
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movl (v), %eax
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movl 4(v), %edx
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subl $1, %eax
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sbbl $0, %edx
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movl %eax, (v)
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movl %edx, 4(v)
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RET_ENDP
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#undef v
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#define v %esi
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BEGIN(add_unless)
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addl %eax, %ecx
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adcl %edx, %edi
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addl (v), %eax
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adcl 4(v), %edx
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cmpl %eax, %ecx
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je 3f
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1:
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movl %eax, (v)
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movl %edx, 4(v)
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movl $1, %eax
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2:
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RET
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3:
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cmpl %edx, %edi
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jne 1b
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xorl %eax, %eax
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jmp 2b
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ENDP
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#undef v
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#define v %esi
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BEGIN(inc_not_zero)
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movl (v), %eax
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movl 4(v), %edx
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testl %eax, %eax
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je 3f
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1:
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addl $1, %eax
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adcl $0, %edx
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movl %eax, (v)
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movl %edx, 4(v)
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movl $1, %eax
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2:
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RET
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3:
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testl %edx, %edx
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jne 1b
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jmp 2b
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ENDP
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#undef v
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#define v %esi
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BEGIN(dec_if_positive)
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movl (v), %eax
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movl 4(v), %edx
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subl $1, %eax
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sbbl $0, %edx
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js 1f
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movl %eax, (v)
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movl %edx, 4(v)
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1:
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RET_ENDP
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#undef v
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