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Supported a complete jump_label implementation based on the ARM64 and RV64 version and add the CONFIG_JUMP_LABEL=y to the defconfig. Testing was conducted using a dedicated test module jump-label-test, provided in the link below. For detailed steps, please refer to the README also at the provided link. Link: https://github.com/ChenMiaoi/GSoC-2025-Final-Report/tree/main/tests/jump-label-test Test Environment: - Hardware: QEMU emulated OR1K - Kernel Version: 6.17.0-rc3-dirty - Configs: CONFIG_MODULES=y,CONFIG_MODULE_UNLOAD=y - Toolchain: or1k-none-linux-musl-gcc 15.1.0 Test Results: $ insmod jump_label_test.ko [ 32.590000] Jump label performance test module loaded [ 35.250000] Normal branch time: 1241327150 ns (124 ns per iteration) [ 35.250000] Jump label (false) time: 706422700 ns (70 ns per iteration) [ 35.250000] Jump label (true) time: 708913450 ns (70 ns per iteration) $ rmmod jump_label_test.ko [ 72.210000] Jump label test module unloaded The results show approximately 43% improvement in branch performance when using jump labels compared to traditional branches. Link: https://lore.kernel.org/openrisc/aLsZ9S3X0OpKy1RM@antec/T/#u Signed-off-by: chenmiao <chenmiao.ku@gmail.com> Signed-off-by: Stafford Horne <shorne@gmail.com>
73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2025 Chen Miao
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*
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* Based on arch/arm/include/asm/jump_label.h
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*/
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#ifndef __ASM_OPENRISC_JUMP_LABEL_H
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#define __ASM_OPENRISC_JUMP_LABEL_H
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#ifndef __ASSEMBLER__
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#include <linux/types.h>
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#include <asm/insn-def.h>
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#define HAVE_JUMP_LABEL_BATCH
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#define JUMP_LABEL_NOP_SIZE OPENRISC_INSN_SIZE
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/**
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* JUMP_TABLE_ENTRY - Create a jump table entry
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* @key: Jump key identifier (typically a symbol address)
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* @label: Target label address
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*
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* This macro creates a jump table entry in the dedicated kernel section (__jump_table).
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* Each entry contains the following information:
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* Offset from current instruction to jump instruction (1b - .)
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* Offset from current instruction to target label (label - .)
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* Offset from current instruction to key identifier (key - .)
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*/
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#define JUMP_TABLE_ENTRY(key, label) \
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".pushsection __jump_table, \"aw\" \n\t" \
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".align 4 \n\t" \
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".long 1b - ., " label " - . \n\t" \
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".long " key " - . \n\t" \
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".popsection \n\t"
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#define ARCH_STATIC_BRANCH_ASM(key, label) \
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".align 4 \n\t" \
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"1: l.nop \n\t" \
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" l.nop \n\t" \
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JUMP_TABLE_ENTRY(key, label)
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static __always_inline bool arch_static_branch(struct static_key *const key,
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const bool branch)
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{
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asm goto (ARCH_STATIC_BRANCH_ASM("%0", "%l[l_yes]")
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::"i"(&((char *)key)[branch])::l_yes);
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return false;
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l_yes:
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return true;
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}
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#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label) \
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".align 4 \n\t" \
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"1: l.j " label " \n\t" \
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" l.nop \n\t" \
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JUMP_TABLE_ENTRY(key, label)
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static __always_inline bool
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arch_static_branch_jump(struct static_key *const key, const bool branch)
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{
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asm goto (ARCH_STATIC_BRANCH_JUMP_ASM("%0", "%l[l_yes]")
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::"i"(&((char *)key)[branch])::l_yes);
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return false;
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l_yes:
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return true;
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}
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#endif /* __ASSEMBLER__ */
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#endif /* __ASM_OPENRISC_JUMP_LABEL_H */
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