mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
synced 2025-08-28 18:10:32 +00:00
9fbd18cf4c
This commit adds support for BPF dynamic code modification on the LoongArch architecture: 1. Add bpf_arch_text_copy() for instruction block copying. 2. Add bpf_arch_text_poke() for runtime instruction patching. 3. Add bpf_arch_text_invalidate() for code invalidation. On LoongArch, since symbol addresses in the direct mapping region can't be reached via relative jump instructions from the paged mapping region, we use the move_imm+jirl instruction pair as absolute jump instructions. These require 2-5 instructions, so we reserve 5 NOP instructions in the program as placeholders for function jumps. The larch_insn_text_copy() function is solely used for BPF. And the use of larch_insn_text_copy() requires PAGE_SIZE alignment. Currently, only the size of the BPF trampoline is page-aligned. Co-developed-by: George Guo <guodongtai@kylinos.cn> Signed-off-by: George Guo <guodongtai@kylinos.cn> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
413 lines
8.9 KiB
C
413 lines
8.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#include <linux/sizes.h>
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#include <linux/uaccess.h>
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#include <linux/set_memory.h>
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#include <linux/stop_machine.h>
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#include <asm/cacheflush.h>
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#include <asm/inst.h>
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static DEFINE_RAW_SPINLOCK(patch_lock);
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void simu_pc(struct pt_regs *regs, union loongarch_instruction insn)
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{
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unsigned long pc = regs->csr_era;
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unsigned int rd = insn.reg1i20_format.rd;
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unsigned int imm = insn.reg1i20_format.immediate;
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if (pc & 3) {
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pr_warn("%s: invalid pc 0x%lx\n", __func__, pc);
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return;
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}
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switch (insn.reg1i20_format.opcode) {
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case pcaddi_op:
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regs->regs[rd] = pc + sign_extend64(imm << 2, 21);
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break;
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case pcaddu12i_op:
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regs->regs[rd] = pc + sign_extend64(imm << 12, 31);
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break;
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case pcaddu18i_op:
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regs->regs[rd] = pc + sign_extend64(imm << 18, 37);
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break;
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case pcalau12i_op:
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regs->regs[rd] = pc + sign_extend64(imm << 12, 31);
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regs->regs[rd] &= ~((1 << 12) - 1);
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break;
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default:
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pr_info("%s: unknown opcode\n", __func__);
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return;
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}
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regs->csr_era += LOONGARCH_INSN_SIZE;
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}
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void simu_branch(struct pt_regs *regs, union loongarch_instruction insn)
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{
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unsigned int imm, imm_l, imm_h, rd, rj;
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unsigned long pc = regs->csr_era;
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if (pc & 3) {
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pr_warn("%s: invalid pc 0x%lx\n", __func__, pc);
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return;
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}
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imm_l = insn.reg0i26_format.immediate_l;
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imm_h = insn.reg0i26_format.immediate_h;
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switch (insn.reg0i26_format.opcode) {
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case b_op:
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regs->csr_era = pc + sign_extend64((imm_h << 16 | imm_l) << 2, 27);
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return;
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case bl_op:
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regs->csr_era = pc + sign_extend64((imm_h << 16 | imm_l) << 2, 27);
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regs->regs[1] = pc + LOONGARCH_INSN_SIZE;
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return;
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}
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imm_l = insn.reg1i21_format.immediate_l;
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imm_h = insn.reg1i21_format.immediate_h;
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rj = insn.reg1i21_format.rj;
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switch (insn.reg1i21_format.opcode) {
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case beqz_op:
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if (regs->regs[rj] == 0)
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regs->csr_era = pc + sign_extend64((imm_h << 16 | imm_l) << 2, 22);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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return;
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case bnez_op:
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if (regs->regs[rj] != 0)
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regs->csr_era = pc + sign_extend64((imm_h << 16 | imm_l) << 2, 22);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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return;
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}
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imm = insn.reg2i16_format.immediate;
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rj = insn.reg2i16_format.rj;
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rd = insn.reg2i16_format.rd;
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switch (insn.reg2i16_format.opcode) {
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case beq_op:
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if (regs->regs[rj] == regs->regs[rd])
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regs->csr_era = pc + sign_extend64(imm << 2, 17);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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break;
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case bne_op:
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if (regs->regs[rj] != regs->regs[rd])
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regs->csr_era = pc + sign_extend64(imm << 2, 17);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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break;
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case blt_op:
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if ((long)regs->regs[rj] < (long)regs->regs[rd])
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regs->csr_era = pc + sign_extend64(imm << 2, 17);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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break;
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case bge_op:
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if ((long)regs->regs[rj] >= (long)regs->regs[rd])
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regs->csr_era = pc + sign_extend64(imm << 2, 17);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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break;
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case bltu_op:
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if (regs->regs[rj] < regs->regs[rd])
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regs->csr_era = pc + sign_extend64(imm << 2, 17);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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break;
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case bgeu_op:
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if (regs->regs[rj] >= regs->regs[rd])
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regs->csr_era = pc + sign_extend64(imm << 2, 17);
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else
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regs->csr_era = pc + LOONGARCH_INSN_SIZE;
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break;
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case jirl_op:
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regs->csr_era = regs->regs[rj] + sign_extend64(imm << 2, 17);
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regs->regs[rd] = pc + LOONGARCH_INSN_SIZE;
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break;
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default:
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pr_info("%s: unknown opcode\n", __func__);
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return;
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}
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}
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bool insns_not_supported(union loongarch_instruction insn)
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{
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switch (insn.reg3_format.opcode) {
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case amswapw_op ... ammindbdu_op:
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pr_notice("atomic memory access instructions are not supported\n");
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return true;
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}
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switch (insn.reg2i14_format.opcode) {
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case llw_op:
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case lld_op:
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case scw_op:
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case scd_op:
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pr_notice("ll and sc instructions are not supported\n");
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return true;
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}
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switch (insn.reg1i21_format.opcode) {
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case bceqz_op:
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pr_notice("bceqz and bcnez instructions are not supported\n");
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return true;
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}
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return false;
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}
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bool insns_need_simulation(union loongarch_instruction insn)
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{
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if (is_pc_ins(&insn))
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return true;
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if (is_branch_ins(&insn))
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return true;
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return false;
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}
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void arch_simulate_insn(union loongarch_instruction insn, struct pt_regs *regs)
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{
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if (is_pc_ins(&insn))
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simu_pc(regs, insn);
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else if (is_branch_ins(&insn))
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simu_branch(regs, insn);
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}
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int larch_insn_read(void *addr, u32 *insnp)
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{
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int ret;
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u32 val;
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ret = copy_from_kernel_nofault(&val, addr, LOONGARCH_INSN_SIZE);
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if (!ret)
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*insnp = val;
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return ret;
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}
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int larch_insn_write(void *addr, u32 insn)
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{
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int ret;
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unsigned long flags = 0;
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raw_spin_lock_irqsave(&patch_lock, flags);
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ret = copy_to_kernel_nofault(addr, &insn, LOONGARCH_INSN_SIZE);
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raw_spin_unlock_irqrestore(&patch_lock, flags);
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return ret;
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}
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int larch_insn_patch_text(void *addr, u32 insn)
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{
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int ret;
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u32 *tp = addr;
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if ((unsigned long)tp & 3)
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return -EINVAL;
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ret = larch_insn_write(tp, insn);
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if (!ret)
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flush_icache_range((unsigned long)tp,
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(unsigned long)tp + LOONGARCH_INSN_SIZE);
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return ret;
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}
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struct insn_copy {
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void *dst;
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void *src;
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size_t len;
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unsigned int cpu;
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};
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static int text_copy_cb(void *data)
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{
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int ret = 0;
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struct insn_copy *copy = data;
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if (smp_processor_id() == copy->cpu) {
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ret = copy_to_kernel_nofault(copy->dst, copy->src, copy->len);
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if (ret)
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pr_err("%s: operation failed\n", __func__);
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}
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flush_icache_range((unsigned long)copy->dst, (unsigned long)copy->dst + copy->len);
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return ret;
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}
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int larch_insn_text_copy(void *dst, void *src, size_t len)
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{
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int ret = 0;
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size_t start, end;
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struct insn_copy copy = {
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.dst = dst,
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.src = src,
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.len = len,
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.cpu = smp_processor_id(),
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};
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start = round_down((size_t)dst, PAGE_SIZE);
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end = round_up((size_t)dst + len, PAGE_SIZE);
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set_memory_rw(start, (end - start) / PAGE_SIZE);
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ret = stop_machine(text_copy_cb, ©, cpu_online_mask);
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set_memory_rox(start, (end - start) / PAGE_SIZE);
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return ret;
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}
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u32 larch_insn_gen_nop(void)
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{
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return INSN_NOP;
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}
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u32 larch_insn_gen_b(unsigned long pc, unsigned long dest)
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{
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long offset = dest - pc;
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union loongarch_instruction insn;
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if ((offset & 3) || offset < -SZ_128M || offset >= SZ_128M) {
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pr_warn("The generated b instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_b(&insn, offset >> 2);
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return insn.word;
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}
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u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest)
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{
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long offset = dest - pc;
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union loongarch_instruction insn;
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if ((offset & 3) || offset < -SZ_128M || offset >= SZ_128M) {
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pr_warn("The generated bl instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_bl(&insn, offset >> 2);
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return insn.word;
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}
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u32 larch_insn_gen_break(int imm)
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{
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union loongarch_instruction insn;
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if (imm < 0 || imm >= SZ_32K) {
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pr_warn("The generated break instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_break(&insn, imm);
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return insn.word;
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}
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u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj, enum loongarch_gpr rk)
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{
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union loongarch_instruction insn;
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emit_or(&insn, rd, rj, rk);
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return insn.word;
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}
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u32 larch_insn_gen_move(enum loongarch_gpr rd, enum loongarch_gpr rj)
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{
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return larch_insn_gen_or(rd, rj, 0);
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}
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u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm)
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{
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union loongarch_instruction insn;
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if (imm < -SZ_512K || imm >= SZ_512K) {
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pr_warn("The generated lu12i.w instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_lu12iw(&insn, rd, imm);
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return insn.word;
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}
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u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm)
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{
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union loongarch_instruction insn;
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if (imm < -SZ_512K || imm >= SZ_512K) {
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pr_warn("The generated lu32i.d instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_lu32id(&insn, rd, imm);
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return insn.word;
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}
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u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
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{
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union loongarch_instruction insn;
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if (imm < -SZ_2K || imm >= SZ_2K) {
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pr_warn("The generated lu52i.d instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_lu52id(&insn, rd, rj, imm);
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return insn.word;
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}
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u32 larch_insn_gen_beq(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
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{
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union loongarch_instruction insn;
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if ((imm & 3) || imm < -SZ_128K || imm >= SZ_128K) {
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pr_warn("The generated beq instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_beq(&insn, rj, rd, imm >> 2);
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return insn.word;
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}
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u32 larch_insn_gen_bne(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
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{
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union loongarch_instruction insn;
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if ((imm & 3) || imm < -SZ_128K || imm >= SZ_128K) {
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pr_warn("The generated bne instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_bne(&insn, rj, rd, imm >> 2);
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return insn.word;
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}
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u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
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{
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union loongarch_instruction insn;
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if ((imm & 3) || imm < -SZ_128K || imm >= SZ_128K) {
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pr_warn("The generated jirl instruction is out of range.\n");
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return INSN_BREAK;
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}
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emit_jirl(&insn, rd, rj, imm >> 2);
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return insn.word;
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}
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