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Commit 57d8e02e authored by Richard Weinberger's avatar Richard Weinberger Committed by Linus Torvalds
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um: mdd support for 64 bit atomic operations 

This adds support for 64 bit atomic operations on 32 bit UML systems.  XFS
needs them since 2.6.38.

  $ make ARCH=um SUBARCH=i386
  ...
    LD      .tmp_vmlinux1
  fs/built-in.o: In function `xlog_regrant_reserve_log_space':
  xfs_log.c:(.text+0xd8584): undefined reference to `atomic64_read_386'
  xfs_log.c:(.text+0xd85ac): undefined reference to `cmpxchg8b_emu'
  ...

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=32812



Reported-by: default avatarMartin Walch <walch.martin@web.de>
Tested-by: default avatarMartin Walch <walch.martin@web.de>
Cc: Martin Walch <walch.martin@web.de>
Cc: <stable@kernel.org> [2.6.38.x 084189a8: um: disable CONFIG_CMPXCHG_LOCAL]
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f755a042

arch/um/sys-i386/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 


obj-y = bug.o bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \

	ptrace_user.o setjmp.o signal.o stub.o stub_segv.o syscalls.o sysrq.o \

	sys_call_table.o tls.o

	sys_call_table.o tls.o atomic64_cx8_32.o



obj-$(CONFIG_BINFMT_ELF) += elfcore.o

arch/um/sys-i386/atomic64_cx8_32.S

0 → 100644
+225 −0
Original line number Diff line number Diff line 
/*

 * atomic64_t for 586+

 *

 * Copied from arch/x86/lib/atomic64_cx8_32.S

 *

 * Copyright © 2010  Luca Barbieri

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 */



#include <linux/linkage.h>

#include <asm/alternative-asm.h>

#include <asm/dwarf2.h>



.macro SAVE reg

	pushl_cfi %\reg

	CFI_REL_OFFSET \reg, 0

.endm



.macro RESTORE reg

	popl_cfi %\reg

	CFI_RESTORE \reg

.endm



.macro read64 reg

	movl %ebx, %eax

	movl %ecx, %edx

/* we need LOCK_PREFIX since otherwise cmpxchg8b always does the write */

	LOCK_PREFIX

	cmpxchg8b (\reg)

.endm



ENTRY(atomic64_read_cx8)

	CFI_STARTPROC



	read64 %ecx

	ret

	CFI_ENDPROC

ENDPROC(atomic64_read_cx8)



ENTRY(atomic64_set_cx8)

	CFI_STARTPROC



1:

/* we don't need LOCK_PREFIX since aligned 64-bit writes

 * are atomic on 586 and newer */

	cmpxchg8b (%esi)

	jne 1b



	ret

	CFI_ENDPROC

ENDPROC(atomic64_set_cx8)



ENTRY(atomic64_xchg_cx8)

	CFI_STARTPROC



	movl %ebx, %eax

	movl %ecx, %edx

1:

	LOCK_PREFIX

	cmpxchg8b (%esi)

	jne 1b



	ret

	CFI_ENDPROC

ENDPROC(atomic64_xchg_cx8)



.macro addsub_return func ins insc

ENTRY(atomic64_\func\()_return_cx8)

	CFI_STARTPROC

	SAVE ebp

	SAVE ebx

	SAVE esi

	SAVE edi



	movl %eax, %esi

	movl %edx, %edi

	movl %ecx, %ebp



	read64 %ebp

1:

	movl %eax, %ebx

	movl %edx, %ecx

	\ins\()l %esi, %ebx

	\insc\()l %edi, %ecx

	LOCK_PREFIX

	cmpxchg8b (%ebp)

	jne 1b



10:

	movl %ebx, %eax

	movl %ecx, %edx

	RESTORE edi

	RESTORE esi

	RESTORE ebx

	RESTORE ebp

	ret

	CFI_ENDPROC

ENDPROC(atomic64_\func\()_return_cx8)

.endm



addsub_return add add adc

addsub_return sub sub sbb



.macro incdec_return func ins insc

ENTRY(atomic64_\func\()_return_cx8)

	CFI_STARTPROC

	SAVE ebx



	read64 %esi

1:

	movl %eax, %ebx

	movl %edx, %ecx

	\ins\()l $1, %ebx

	\insc\()l $0, %ecx

	LOCK_PREFIX

	cmpxchg8b (%esi)

	jne 1b



10:

	movl %ebx, %eax

	movl %ecx, %edx

	RESTORE ebx

	ret

	CFI_ENDPROC

ENDPROC(atomic64_\func\()_return_cx8)

.endm



incdec_return inc add adc

incdec_return dec sub sbb



ENTRY(atomic64_dec_if_positive_cx8)

	CFI_STARTPROC

	SAVE ebx



	read64 %esi

1:

	movl %eax, %ebx

	movl %edx, %ecx

	subl $1, %ebx

	sbb $0, %ecx

	js 2f

	LOCK_PREFIX

	cmpxchg8b (%esi)

	jne 1b



2:

	movl %ebx, %eax

	movl %ecx, %edx

	RESTORE ebx

	ret

	CFI_ENDPROC

ENDPROC(atomic64_dec_if_positive_cx8)



ENTRY(atomic64_add_unless_cx8)

	CFI_STARTPROC

	SAVE ebp

	SAVE ebx

/* these just push these two parameters on the stack */

	SAVE edi

	SAVE esi



	movl %ecx, %ebp

	movl %eax, %esi

	movl %edx, %edi



	read64 %ebp

1:

	cmpl %eax, 0(%esp)

	je 4f

2:

	movl %eax, %ebx

	movl %edx, %ecx

	addl %esi, %ebx

	adcl %edi, %ecx

	LOCK_PREFIX

	cmpxchg8b (%ebp)

	jne 1b



	movl $1, %eax

3:

	addl $8, %esp

	CFI_ADJUST_CFA_OFFSET -8

	RESTORE ebx

	RESTORE ebp

	ret

4:

	cmpl %edx, 4(%esp)

	jne 2b

	xorl %eax, %eax

	jmp 3b

	CFI_ENDPROC

ENDPROC(atomic64_add_unless_cx8)



ENTRY(atomic64_inc_not_zero_cx8)

	CFI_STARTPROC

	SAVE ebx



	read64 %esi

1:

	testl %eax, %eax

	je 4f

2:

	movl %eax, %ebx

	movl %edx, %ecx

	addl $1, %ebx

	adcl $0, %ecx

	LOCK_PREFIX

	cmpxchg8b (%esi)

	jne 1b



	movl $1, %eax

3:

	RESTORE ebx

	ret

4:

	testl %edx, %edx

	jne 2b

	jmp 3b

	CFI_ENDPROC

ENDPROC(atomic64_inc_not_zero_cx8)