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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9b6584e35f
MIPSr6 introduced compact branches which have no delay slots. Make use of them for jump labels in order to avoid the need for a nop to fill the branch or jump delay slot, saving 4 bytes of code for each static branch. Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org
91 lines
2.4 KiB
C
91 lines
2.4 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (c) 2010 Cavium Networks, Inc.
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*/
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#include <linux/jump_label.h>
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#include <linux/kernel.h>
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#include <linux/memory.h>
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#include <linux/mutex.h>
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#include <linux/types.h>
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#include <linux/cpu.h>
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#include <asm/cacheflush.h>
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#include <asm/inst.h>
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/*
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* Define parameters for the standard MIPS and the microMIPS jump
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* instruction encoding respectively:
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*
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* - the ISA bit of the target, either 0 or 1 respectively,
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*
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* - the amount the jump target address is shifted right to fit in the
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* immediate field of the machine instruction, either 2 or 1,
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*
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* - the mask determining the size of the jump region relative to the
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* delay-slot instruction, either 256MB or 128MB,
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*
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* - the jump target alignment, either 4 or 2 bytes.
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*/
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#define J_ISA_BIT IS_ENABLED(CONFIG_CPU_MICROMIPS)
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#define J_RANGE_SHIFT (2 - J_ISA_BIT)
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#define J_RANGE_MASK ((1ul << (26 + J_RANGE_SHIFT)) - 1)
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#define J_ALIGN_MASK ((1ul << J_RANGE_SHIFT) - 1)
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void arch_jump_label_transform(struct jump_entry *e,
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enum jump_label_type type)
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{
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union mips_instruction *insn_p;
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union mips_instruction insn;
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long offset;
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insn_p = (union mips_instruction *)msk_isa16_mode(e->code);
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/* Target must have the right alignment and ISA must be preserved. */
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BUG_ON((e->target & J_ALIGN_MASK) != J_ISA_BIT);
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if (type == JUMP_LABEL_JMP) {
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if (!IS_ENABLED(CONFIG_CPU_MICROMIPS) && MIPS_ISA_REV >= 6) {
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offset = e->target - ((unsigned long)insn_p + 4);
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offset >>= 2;
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/*
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* The branch offset must fit in the instruction's 26
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* bit field.
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*/
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WARN_ON((offset >= BIT(25)) ||
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(offset < -(long)BIT(25)));
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insn.j_format.opcode = bc6_op;
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insn.j_format.target = offset;
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} else {
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/*
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* Jump only works within an aligned region its delay
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* slot is in.
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*/
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WARN_ON((e->target & ~J_RANGE_MASK) !=
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((e->code + 4) & ~J_RANGE_MASK));
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insn.j_format.opcode = J_ISA_BIT ? mm_j32_op : j_op;
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insn.j_format.target = e->target >> J_RANGE_SHIFT;
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}
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} else {
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insn.word = 0; /* nop */
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}
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mutex_lock(&text_mutex);
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if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) {
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insn_p->halfword[0] = insn.word >> 16;
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insn_p->halfword[1] = insn.word;
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} else
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*insn_p = insn;
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flush_icache_range((unsigned long)insn_p,
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(unsigned long)insn_p + sizeof(*insn_p));
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mutex_unlock(&text_mutex);
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}
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