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=-20.2 required=3.0 tests=BAYES_00,DATE_IN_PAST_03_06, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,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 92620C432BE for ; Wed, 18 Aug 2021 10:58:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EC3C6108E for ; Wed, 18 Aug 2021 10:58:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235120AbhHRK6e (ORCPT ); Wed, 18 Aug 2021 06:58:34 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:13440 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235207AbhHRK6P (ORCPT ); Wed, 18 Aug 2021 06:58:15 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GqPsC2LN3zdbtX; Wed, 18 Aug 2021 18:53:51 +0800 (CST) Received: from dggema757-chm.china.huawei.com (10.1.198.199) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Wed, 18 Aug 2021 18:57:17 +0800 Received: from localhost.localdomain (10.67.165.2) by dggema757-chm.china.huawei.com (10.1.198.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Wed, 18 Aug 2021 18:57:17 +0800 From: Qi Liu To: , , , , , , CC: , , , , , , Subject: [PATCH v4 2/2] arm64: kprobe: Enable OPTPROBE for arm64 Date: Wed, 18 Aug 2021 15:33:36 +0800 Message-ID: <20210818073336.59678-3-liuqi115@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210818073336.59678-1-liuqi115@huawei.com> References: <20210818073336.59678-1-liuqi115@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.165.2] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggema757-chm.china.huawei.com (10.1.198.199) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch introduce optprobe for ARM64. In optprobe, probed instruction is replaced by a branch instruction to detour buffer. Detour buffer contains trampoline code and a call to optimized_callback(). optimized_callback() calls opt_pre_handler() to execute kprobe handler. Performance of optprobe on Hip08 platform is test using kprobe example module[1] to analyze the latency of a kernel function, and here is the result: [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/samples/kprobes/kretprobe_example.c kprobe before optimized: [280709.846380] do_empty returned 0 and took 1530 ns to execute [280709.852057] do_empty returned 0 and took 550 ns to execute [280709.857631] do_empty returned 0 and took 440 ns to execute [280709.863215] do_empty returned 0 and took 380 ns to execute [280709.868787] do_empty returned 0 and took 360 ns to execute [280709.874362] do_empty returned 0 and took 340 ns to execute [280709.879936] do_empty returned 0 and took 320 ns to execute [280709.885505] do_empty returned 0 and took 300 ns to execute [280709.891075] do_empty returned 0 and took 280 ns to execute [280709.896646] do_empty returned 0 and took 290 ns to execute [280709.902220] do_empty returned 0 and took 290 ns to execute [280709.907807] do_empty returned 0 and took 290 ns to execute optprobe: [ 2965.964572] do_empty returned 0 and took 90 ns to execute [ 2965.969952] do_empty returned 0 and took 80 ns to execute [ 2965.975332] do_empty returned 0 and took 70 ns to execute [ 2965.980714] do_empty returned 0 and took 60 ns to execute [ 2965.986128] do_empty returned 0 and took 80 ns to execute [ 2965.991507] do_empty returned 0 and took 70 ns to execute [ 2965.996884] do_empty returned 0 and took 70 ns to execute [ 2966.002262] do_empty returned 0 and took 80 ns to execute [ 2966.007642] do_empty returned 0 and took 70 ns to execute [ 2966.013020] do_empty returned 0 and took 70 ns to execute [ 2966.018400] do_empty returned 0 and took 70 ns to execute [ 2966.023779] do_empty returned 0 and took 70 ns to execute [ 2966.029158] do_empty returned 0 and took 70 ns to execute Signed-off-by: Qi Liu Note: To guarantee the offset between probe point and kprobe pre_handler is smaller than 128MiB, users should set CONFIG_RANDOMIZE_MODULE_REGION_FULL=N or set nokaslr in command line, or optprobe will not work and fall back to normal kprobe. --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/kprobes.h | 24 ++ arch/arm64/kernel/probes/Makefile | 2 + arch/arm64/kernel/probes/kprobes.c | 19 +- arch/arm64/kernel/probes/opt_arm64.c | 276 ++++++++++++++++++ .../arm64/kernel/probes/optprobe_trampoline.S | 37 +++ 6 files changed, 356 insertions(+), 3 deletions(-) create mode 100644 arch/arm64/kernel/probes/opt_arm64.c create mode 100644 arch/arm64/kernel/probes/optprobe_trampoline.S diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b5b13a932561..b05d1d275d87 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -200,6 +200,7 @@ config ARM64 select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES + select HAVE_OPTPROBES select HAVE_KRETPROBES select HAVE_GENERIC_VDSO select IOMMU_DMA if IOMMU_SUPPORT diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h index 5d38ff4a4806..6b2fdd2ad7d8 100644 --- a/arch/arm64/include/asm/kprobes.h +++ b/arch/arm64/include/asm/kprobes.h @@ -39,6 +39,30 @@ void arch_remove_kprobe(struct kprobe *); int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr); int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); + +#define RELATIVEJUMP_SIZE (4) +#define MAX_COPIED_INSN DIV_ROUND_UP(RELATIVEJUMP_SIZE, sizeof(kprobe_opcode_t)) +struct arch_optimized_insn { + kprobe_opcode_t copied_insn[MAX_COPIED_INSN]; + /* detour code buffer */ + kprobe_opcode_t *insn; +}; + +/* optinsn template addresses */ +extern __visible kprobe_opcode_t optprobe_template_entry[]; +extern __visible kprobe_opcode_t optprobe_template_val[]; +extern __visible kprobe_opcode_t optprobe_template_call[]; +extern __visible kprobe_opcode_t optprobe_template_end[]; +extern __visible kprobe_opcode_t optprobe_template_restore_begin[]; +extern __visible kprobe_opcode_t optprobe_template_restore_orig_insn[]; +extern __visible kprobe_opcode_t optprobe_template_restore_end[]; +extern __visible kprobe_opcode_t optprobe_template_max_length[]; + +#define MAX_OPTIMIZED_LENGTH 4 +#define MAX_OPTINSN_SIZE \ + ((unsigned long)optprobe_template_end - \ + (unsigned long)optprobe_template_entry) + void kretprobe_trampoline(void); void __kprobes *trampoline_probe_handler(struct pt_regs *regs); diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile index 8e4be92e25b1..07105fd3261d 100644 --- a/arch/arm64/kernel/probes/Makefile +++ b/arch/arm64/kernel/probes/Makefile @@ -4,3 +4,5 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \ simulate-insn.o obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \ simulate-insn.o +obj-$(CONFIG_OPTPROBES) += opt_arm64.o \ + optprobe_trampoline.o diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 6dbcc89f6662..83755ad62abe 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -113,9 +114,21 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) void *alloc_insn_page(void) { - return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END, - GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS, - NUMA_NO_NODE, __builtin_return_address(0)); + void *page; + + page = module_alloc(PAGE_SIZE); + if (!page) + return NULL; + + set_vm_flush_reset_perms(page); + /* + * First make the page read-only, and only then make it executable to + * prevent it from being W+X in between. + */ + set_memory_ro((unsigned long)page, 1); + set_memory_x((unsigned long)page, 1); + + return page; } /* arm kprobe: install breakpoint in text */ diff --git a/arch/arm64/kernel/probes/opt_arm64.c b/arch/arm64/kernel/probes/opt_arm64.c new file mode 100644 index 000000000000..4de535bee534 --- /dev/null +++ b/arch/arm64/kernel/probes/opt_arm64.c @@ -0,0 +1,276 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Code for Kernel probes Jump optimization. + * + * Copyright (C) 2021 Hisilicon Limited + */ + +#include +#include + +#include +#include +#include +#include + +#define TMPL_VAL_IDX \ + (optprobe_template_val - optprobe_template_entry) +#define TMPL_CALL_BACK \ + (optprobe_template_call - optprobe_template_entry) +#define TMPL_END_IDX \ + (optprobe_template_end - optprobe_template_entry) +#define TMPL_RESTORE_ORIGN_INSN \ + (optprobe_template_restore_orig_insn - optprobe_template_entry) +#define TMPL_RESTORE_END \ + (optprobe_template_restore_end - optprobe_template_entry) +#define TMPL_MAX_LENGTH \ + (optprobe_template_max_length - optprobe_template_entry) +#define OPTPROBE_BATCH_SIZE 64 + +int arch_check_optimized_kprobe(struct optimized_kprobe *op) +{ + return 0; +} + +int arch_prepared_optinsn(struct arch_optimized_insn *optinsn) +{ + return optinsn->insn != NULL; +} + +int arch_within_optimized_kprobe(struct optimized_kprobe *op, + unsigned long addr) +{ + return ((unsigned long)op->kp.addr <= addr && + (unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr); +} + +static void +optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) +{ + /* This is possible if op is under delayed unoptimizing */ + if (kprobe_disabled(&op->kp)) + return; + + preempt_disable(); + + if (kprobe_running()) { + kprobes_inc_nmissed_count(&op->kp); + } else { + __this_cpu_write(current_kprobe, &op->kp); + regs->pc = (unsigned long)op->kp.addr; + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; + opt_pre_handler(&op->kp, regs); + __this_cpu_write(current_kprobe, NULL); + } + + preempt_enable_no_resched(); +} +NOKPROBE_SYMBOL(optimized_callback) + +static bool is_offset_in_range(unsigned long start, unsigned long end) +{ + long offset = end - start; + + /* + * Verify if the address gap is in 128MiB range, because this uses + * a relative jump. + * + * kprobe opt use a 'b' instruction to branch to optinsn.insn. + * According to ARM manual, branch instruction is: + * + * 31 30 25 0 + * +----+---+---+---+---+---+---------------+ + * |cond| 0 | 0 | 1 | 0 | 1 | imm26 | + * +----+---+---+---+---+---+---------------+ + * + * imm26 is a signed 26 bits integer. The real branch offset is computed + * by: imm64 = SignExtend(imm26:'00', 64); + * + * So the maximum forward branch should be: + * (0x01ffffff << 2) = 0x07fffffc + * The maximum backward branch should be: + * (0xfe000000 << 2) = 0xFFFFFFFFF8000000 = -0x08000000 + * + * We can simply check (rel & 0xf8000003): + * if rel is positive, (rel & 0xf8000003) should be 0 + * if rel is negitive, (rel & 0xf8000003) should be 0xf8000000 + * the last '3' is used for alignment checking. + */ + return (offset >= -0x8000000 && offset <= 0x7fffffc && !(offset & 0x3)); +} + +int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, + struct kprobe *orig) +{ + kprobe_opcode_t *code, *buf; + void **addrs; + u32 insn; + int ret, i; + + addrs = kcalloc(TMPL_MAX_LENGTH, sizeof(void *), GFP_KERNEL); + if (!addrs) + return -ENOMEM; + + buf = kcalloc(TMPL_MAX_LENGTH, sizeof(kprobe_opcode_t), GFP_KERNEL); + if (!buf) { + kfree(addrs); + return -ENOMEM; + } + + code = get_optinsn_slot(); + if (!code) { + kfree(addrs); + kfree(buf); + return -ENOMEM; + } + + if (!is_offset_in_range((unsigned long)code, + (unsigned long)orig->addr + 8)) { + ret = -ERANGE; + goto error; + } + + if (!is_offset_in_range((unsigned long)code + TMPL_CALL_BACK, + (unsigned long)optimized_callback)) { + ret = -ERANGE; + goto error; + } + + if (!is_offset_in_range((unsigned long)&code[TMPL_RESTORE_END], + (unsigned long)op->kp.addr + 4)) { + ret = -ERANGE; + goto error; + } + + memcpy(buf, optprobe_template_entry, + TMPL_END_IDX * sizeof(kprobe_opcode_t)); + + buf[TMPL_VAL_IDX] = FIELD_GET(GENMASK(31, 0), (unsigned long long)op); + buf[TMPL_VAL_IDX + 1] = + FIELD_GET(GENMASK(63, 32), (unsigned long long)op); + buf[TMPL_RESTORE_ORIGN_INSN] = orig->opcode; + + insn = aarch64_insn_gen_branch_imm( + (unsigned long)(&code[TMPL_CALL_BACK]), + (unsigned long)optimized_callback, AARCH64_INSN_BRANCH_LINK); + buf[TMPL_CALL_BACK] = insn; + + insn = aarch64_insn_gen_branch_imm( + (unsigned long)(&code[TMPL_RESTORE_END]), + (unsigned long)(op->kp.addr) + 4, AARCH64_INSN_BRANCH_NOLINK); + buf[TMPL_RESTORE_END] = insn; + + /* Setup template */ + for (i = 0; i < TMPL_MAX_LENGTH; i++) + addrs[i] = code + i; + + ret = aarch64_insn_patch_text(addrs, buf, TMPL_MAX_LENGTH); + if (ret < 0) + goto error; + + flush_icache_range((unsigned long)code, + (unsigned long)(&code[TMPL_END_IDX])); + + /* Set op->optinsn.insn means prepared. */ + op->optinsn.insn = code; + +out: + kfree(addrs); + kfree(buf); + return ret; + +error: + free_optinsn_slot(code, 0); + goto out; +} + +void arch_optimize_kprobes(struct list_head *oplist) +{ + struct optimized_kprobe *op, *tmp; + kprobe_opcode_t *insns; + void **addrs; + int i = 0; + + addrs = kcalloc(OPTPROBE_BATCH_SIZE, sizeof(void *), GFP_KERNEL); + if (!addrs) + return; + + insns = kcalloc(OPTPROBE_BATCH_SIZE, sizeof(kprobe_opcode_t), GFP_KERNEL); + if (!insns) { + kfree(addrs); + return; + } + + list_for_each_entry_safe(op, tmp, oplist, list) { + WARN_ON(kprobe_disabled(&op->kp)); + + /* + * Backup instructions which will be replaced + * by jump address + */ + memcpy(op->optinsn.copied_insn, op->kp.addr, + RELATIVEJUMP_SIZE); + + addrs[i] = (void *)op->kp.addr; + insns[i] = aarch64_insn_gen_branch_imm((unsigned long)op->kp.addr, + (unsigned long)op->optinsn.insn, + AARCH64_INSN_BRANCH_NOLINK); + + list_del_init(&op->list); + if (++i == OPTPROBE_BATCH_SIZE) + break; + } + + aarch64_insn_patch_text(addrs, insns, i); + kfree(addrs); + kfree(insns); +} + +void arch_unoptimize_kprobe(struct optimized_kprobe *op) +{ + arch_arm_kprobe(&op->kp); +} + +/* + * Recover original instructions and breakpoints from relative jumps. + * Caller must call with locking kprobe_mutex. + */ +void arch_unoptimize_kprobes(struct list_head *oplist, + struct list_head *done_list) +{ + struct optimized_kprobe *op, *tmp; + kprobe_opcode_t *insns; + void **addrs; + int i = 0; + + addrs = kcalloc(OPTPROBE_BATCH_SIZE, sizeof(void *), GFP_KERNEL); + if (!addrs) + return; + + insns = kcalloc(OPTPROBE_BATCH_SIZE, sizeof(kprobe_opcode_t), GFP_KERNEL); + if (!insns) { + kfree(addrs); + return; + } + + list_for_each_entry_safe(op, tmp, oplist, list) { + addrs[i] = (void *)op->kp.addr; + insns[i] = BRK64_OPCODE_KPROBES; + list_move(&op->list, done_list); + + if (++i == OPTPROBE_BATCH_SIZE) + break; + } + + aarch64_insn_patch_text(addrs, insns, i); + kfree(addrs); + kfree(insns); +} + +void arch_remove_optimized_kprobe(struct optimized_kprobe *op) +{ + if (op->optinsn.insn) { + free_optinsn_slot(op->optinsn.insn, 1); + op->optinsn.insn = NULL; + } +} diff --git a/arch/arm64/kernel/probes/optprobe_trampoline.S b/arch/arm64/kernel/probes/optprobe_trampoline.S new file mode 100644 index 000000000000..24d713d400cd --- /dev/null +++ b/arch/arm64/kernel/probes/optprobe_trampoline.S @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * trampoline entry and return code for optprobes. + */ + +#include +#include +#include + + .global optprobe_template_entry +optprobe_template_entry: + sub sp, sp, #PT_REGS_SIZE + save_all_base_regs + /* Get parameters to optimized_callback() */ + ldr x0, 1f + mov x1, sp + /* Branch to optimized_callback() */ + .global optprobe_template_call +optprobe_template_call: + nop + restore_all_base_regs + ldr lr, [sp, #S_LR] + add sp, sp, #PT_REGS_SIZE + .global optprobe_template_restore_orig_insn +optprobe_template_restore_orig_insn: + nop + .global optprobe_template_restore_end +optprobe_template_restore_end: + nop + .global optprobe_template_end +optprobe_template_end: + .global optprobe_template_val +optprobe_template_val: + 1: .long 0 + .long 0 + .global optprobe_template_max_length +optprobe_template_max_length: -- 2.17.1