From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8801C11F68 for ; Tue, 29 Jun 2021 02:35:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91A5261CEF for ; Tue, 29 Jun 2021 02:35:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231846AbhF2Chv (ORCPT ); Mon, 28 Jun 2021 22:37:51 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:6021 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231743AbhF2Chs (ORCPT ); Mon, 28 Jun 2021 22:37:48 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GDT2y1Qs2zXljJ; Tue, 29 Jun 2021 10:30:02 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 29 Jun 2021 10:35:20 +0800 Received: from huawei.com (10.67.174.169) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 29 Jun 2021 10:35:19 +0800 From: Chen Lifu To: , , , , , , , , , Subject: [PATCH -next 1/2] riscv: implemented auipc simulate instruction Date: Tue, 29 Jun 2021 10:34:54 +0800 Message-ID: <20210629023455.280998-1-chenlifu@huawei.com> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.67.174.169] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To test the kprobe-based event tracing, we prepare a kernel module 'kprobe_test.ko' to add the probes. The assembly codes (partially) of the module are as follows: ... 0000000000000000 : ... 0000000000000038 <.LVL1>: 38: 00000597 auipc a1,0x0 3c: 00058593 mv a1,a1 ... Test the kprobe-based event tracing in qemu-system-riscv64: First, install the kprobe test module: insmod /root/kprobe_test.ko Then, add a probe as a new event at an 'auipc' instruction, the following error occurs due to the instruction not allowed to probe yet: echo "p:auipc kprobe_test:kprobe_test_branch+0x38 epc=%epc opcode=+0(%epc):x32" >> /sys/kernel/debug/tracing/kprobe_events sh: write error: Invalid argument This patch implemented the 'auipc' simulate instruction and allowed to probe it. Merge this patch and perform the test again, the test results are as follows: First, add a probe at the 'auipc' instruction: echo "p:auipc kprobe_test:kprobe_test_branch+0x38 epc=%epc opcode=+0(%epc):x32" >> /sys/kernel/debug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/auipc/enable Then, do something to run to the probe. After that, see the traced information: cat /sys/kernel/debug/tracing/trace sysctl-58 [001] d... 179.126350: auipc: (kprobe_test_branch+0x38/0x10e [kprobe_test]) epc=0xffffffff016122aa opcode=0x100073 Now we can see the traced information. The actual address of the symbol 'kprobe_test_branch' is as follows: cat /proc/kallsyms | grep kprobe_test_branch ffffffff01612272 t kprobe_test_branch [kprobe_test] Based on the traced information and the actual address of the symbol 'kprobe_test_branch', we can also see that the 'auipc' instruction has been replaced by 'ebreak(0x100073)' instruction. -------- Signed-off-by: Chen Lifu --- arch/riscv/kernel/probes/decode-insn.c | 2 +- arch/riscv/kernel/probes/simulate-insn.c | 34 ++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/probes/decode-insn.c b/arch/riscv/kernel/probes/decode-insn.c index 0ed043acc882..5eb03fb61450 100644 --- a/arch/riscv/kernel/probes/decode-insn.c +++ b/arch/riscv/kernel/probes/decode-insn.c @@ -38,11 +38,11 @@ riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *api) RISCV_INSN_REJECTED(c_ebreak, insn); #endif - RISCV_INSN_REJECTED(auipc, insn); RISCV_INSN_REJECTED(branch, insn); RISCV_INSN_SET_SIMULATE(jal, insn); RISCV_INSN_SET_SIMULATE(jalr, insn); + RISCV_INSN_SET_SIMULATE(auipc, insn); return INSN_GOOD; } diff --git a/arch/riscv/kernel/probes/simulate-insn.c b/arch/riscv/kernel/probes/simulate-insn.c index 2519ce26377d..b81719522d5c 100644 --- a/arch/riscv/kernel/probes/simulate-insn.c +++ b/arch/riscv/kernel/probes/simulate-insn.c @@ -83,3 +83,37 @@ bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *reg return ret; } + +#define auipc_rd_idx(opcode) \ + ((opcode >> 7) & 0x1f) + +#define auipc_imm(opcode) \ + ((((opcode) >> 12) & 0xfffff) << 12) + +#if __riscv_xlen == 64 +#define auipc_offset(opcode) sign_extend64(auipc_imm(opcode), 31) +#elif __riscv_xlen == 32 +#define auipc_offset(opcode) auipc_imm(opcode) +#else +#error "Unexpected __riscv_xlen" +#endif + +bool __kprobes simulate_auipc(u32 opcode, unsigned long addr, struct pt_regs *regs) +{ + /* + * auipc instruction: + * 31 12 11 7 6 0 + * | imm[31:12] | rd | opcode | + * 20 5 7 + */ + + u32 rd_idx = auipc_rd_idx(opcode); + unsigned long rd_val = addr + auipc_offset(opcode); + + if (!rv_insn_reg_set_val(regs, rd_idx, rd_val)) + return false; + + instruction_pointer_set(regs, addr + 4); + + return true; +} -- 2.32.0