5a5525b048
getcpu reads the required values for cpu and node with two instructions. This might lead to an inconsistent result if user space gets preempted and migrated to a different CPU between the two instructions. Fix this by using just a single instruction to read both values at once. This is currently rather a theoretical bug, since there is no real NUMA support available (except for NUMA emulation). Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
32 lines
624 B
ArmAsm
32 lines
624 B
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Userland implementation of getcpu() for 64 bits processes in a
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* s390 kernel for use in the vDSO
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*
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* Copyright IBM Corp. 2016
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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*/
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#include <asm/vdso.h>
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#include <asm/asm-offsets.h>
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#include <asm/dwarf.h>
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.text
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.align 4
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.globl __kernel_getcpu
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.type __kernel_getcpu,@function
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__kernel_getcpu:
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CFI_STARTPROC
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sacf 256
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lm %r4,%r5,__VDSO_GETCPU_VAL(%r0)
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sacf 0
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ltgr %r2,%r2
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jz 2f
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st %r5,0(%r2)
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2: ltgr %r3,%r3
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jz 3f
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st %r4,0(%r3)
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3: lghi %r2,0
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br %r14
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CFI_ENDPROC
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.size __kernel_getcpu,.-__kernel_getcpu
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