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65c07e91cc
Implement current with an inline assembly, which makes use of the ALTERNATIVE macro, to read current from lowcore. Provide an alternative instruction with a different offset in case lowcore is relocated. This replaces sequences of two instructions with one instruction. Before: 100076: a5 1e 00 00 llilh %r1,0 10007a: e3 40 13 40 00 04 lg %r4,832(%r1) After: 100076: e3 10 03 40 00 04 lg %r1,832 Kernel image size change: add/remove: 3/17 grow/shrink: 166/2204 up/down: 7122/-24594 (-17472) Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
35 lines
821 B
C
35 lines
821 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* S390 version
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* Copyright IBM Corp. 1999
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* Derived from "include/asm-i386/current.h"
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*/
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#ifndef _S390_CURRENT_H
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#define _S390_CURRENT_H
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#include <asm/lowcore.h>
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#include <asm/machine.h>
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struct task_struct;
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static __always_inline struct task_struct *get_current(void)
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{
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unsigned long ptr, lc_current;
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lc_current = offsetof(struct lowcore, current_task);
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asm_inline(
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ALTERNATIVE(" lg %[ptr],%[offzero](%%r0)\n",
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" lg %[ptr],%[offalt](%%r0)\n",
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ALT_FEATURE(MFEATURE_LOWCORE))
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: [ptr] "=d" (ptr)
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: [offzero] "i" (lc_current),
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[offalt] "i" (lc_current + LOWCORE_ALT_ADDRESS));
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return (struct task_struct *)ptr;
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}
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#define current get_current()
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#endif /* !(_S390_CURRENT_H) */
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