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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>
52 lines
1.2 KiB
C
52 lines
1.2 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/kernel/jump_label.c
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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 <asm/bug.h>
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#include <asm/cacheflush.h>
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#include <asm/text-patching.h>
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bool arch_jump_label_transform_queue(struct jump_entry *entry,
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enum jump_label_type type)
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{
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void *addr = (void *)jump_entry_code(entry);
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u32 insn;
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if (type == JUMP_LABEL_JMP) {
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long offset;
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offset = jump_entry_target(entry) - jump_entry_code(entry);
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/*
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* The actual maximum range of the l.j instruction's offset is -134,217,728
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* ~ 134,217,724 (sign 26-bit imm).
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* For the original jump range, we need to right-shift N by 2 to obtain the
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* instruction's offset.
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*/
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WARN_ON_ONCE(offset < -134217728 || offset > 134217724);
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/* 26bit imm mask */
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offset = (offset >> 2) & 0x03ffffff;
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insn = offset;
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} else {
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insn = OPENRISC_INSN_NOP;
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}
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if (early_boot_irqs_disabled)
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copy_to_kernel_nofault(addr, &insn, sizeof(insn));
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else
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patch_insn_write(addr, insn);
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return true;
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}
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void arch_jump_label_transform_apply(void)
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{
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kick_all_cpus_sync();
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}
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