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[23.128.96.18]) by mx.google.com with ESMTP id f12si4400128ejt.376.2021.06.04.03.53.00; Fri, 04 Jun 2021 03:53:25 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229740AbhFDKwq (ORCPT + 99 others); Fri, 4 Jun 2021 06:52:46 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:4358 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229667AbhFDKwp (ORCPT ); Fri, 4 Jun 2021 06:52:45 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4FxKG64jYDz63cJ; Fri, 4 Jun 2021 18:47:10 +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; Fri, 4 Jun 2021 18:50:57 +0800 Received: from localhost.localdomain (10.69.192.56) 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; Fri, 4 Jun 2021 18:50:56 +0800 From: Qi Liu To: , , CC: , , , , , Subject: [RFC PATCH] arm64: kprobes: Enable OPTPROBE for arm64 Date: Fri, 4 Jun 2021 18:50:39 +0800 Message-ID: <1622803839-27354-1-git-send-email-liuqi115@huawei.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.69.192.56] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) 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. Limitations: - We only support !CONFIG_RANDOMIZE_MODULE_REGION_FULL case to guarantee the offset between probe point and kprobe pre_handler is not larger than 128MiB. 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 --- TODO: - Veneer will be used latter to extend the range of branch and support long jump. arch/arm64/Kconfig | 1 + arch/arm64/include/asm/kprobes.h | 23 +++ arch/arm64/kernel/probes/Makefile | 2 + arch/arm64/kernel/probes/kprobes.c | 19 ++- arch/arm64/kernel/probes/opt-arm64.c | 218 +++++++++++++++++++++++++ arch/arm64/kernel/probes/optprobe_trampoline.S | 81 +++++++++ 6 files changed, 341 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 2e242dbb..ab1a795 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -189,6 +189,7 @@ config ARM64 select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES + select HAVE_OPTPROBES if !RANDOMIZE_MODULE_REGION_FULL 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 5d38ff4..9e1c492 100644 --- a/arch/arm64/include/asm/kprobes.h +++ b/arch/arm64/include/asm/kprobes.h @@ -39,6 +39,29 @@ 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[]; + +#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 8e4be92..52cf5d4 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 66aac28..baaceed 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 @@ -111,9 +112,21 @@ 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 0000000..09ffa75 --- /dev/null +++ b/arch/arm64/kernel/probes/opt-arm64.c @@ -0,0 +1,218 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Code for Kernel probes Jump optimization. + * + * Copyright (C) 2021 Hisilicon Limited + */ + +#include +#include + +#include +#include +/* for aarch64_insn_gen_branch_imm */ +#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) + +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) + +bool is_offset_in_branch_range(long offset) +{ + return (offset >= -0x08000000 && offset <= 0x07fffffc && !(offset & 0x3)); +} + +int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *orig) +{ + kprobe_opcode_t *code; + long rel_chk; + u32 insn, size; + int ret, i; + void *addr; + + code = get_optinsn_slot(); + if (!code) + return -ENOMEM; + + /* + * 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) = 1720x07fffffc = 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. + */ + rel_chk = (unsigned long)code - + (unsigned long)orig->addr + 8; + if (!is_offset_in_branch_range(rel_chk)) { + pr_err("%s is out of branch range.\n", orig->symbol_name); + free_optinsn_slot(code, 0); + return -ERANGE; + } + + /* Setup template */ + size = (TMPL_END_IDX * sizeof(kprobe_opcode_t)) / sizeof(int); + for (i = 0; i < size; i++) { + addr = code + i; + insn = *(optprobe_template_entry + i); + ret = aarch64_insn_patch_text(&addr, &insn, 1); + if (ret < 0) { + free_optinsn_slot(code, 0); + return -ERANGE; + } + } + + /* Set probe information */ + addr = code + TMPL_VAL_IDX; + insn = (unsigned long long)op & 0xffffffff; + aarch64_insn_patch_text(&addr, &insn, 1); + + addr = addr + 4; + insn = ((unsigned long long)op & GENMASK_ULL(63, 32)) >> 32; + aarch64_insn_patch_text(&addr, &insn, 1); + + addr = code + TMPL_CALL_BACK; + insn = aarch64_insn_gen_branch_imm((unsigned long)addr, + (unsigned long)optimized_callback, + AARCH64_INSN_BRANCH_LINK); + aarch64_insn_patch_text(&addr, &insn, 1); + + /* The original probed instruction */ + addr = code + TMPL_RESTORE_ORIGN_INSN; + insn = orig->opcode; + aarch64_insn_patch_text(&addr, &insn, 1); + + /* Jump back to next instruction */ + addr = code + TMPL_RESTORE_END; + insn = aarch64_insn_gen_branch_imm( + (unsigned long)(&code[TMPL_RESTORE_END]), + (unsigned long)(op->kp.addr) + 4, + AARCH64_INSN_BRANCH_NOLINK); + aarch64_insn_patch_text(&addr, &insn, 1); + + flush_icache_range((unsigned long)code, + (unsigned long)(&code[TMPL_END_IDX])); + /* Set op->optinsn.insn means prepared. */ + op->optinsn.insn = code; + return 0; +} + +void arch_optimize_kprobes(struct list_head *oplist) +{ + struct optimized_kprobe *op, *tmp; + + list_for_each_entry_safe(op, tmp, oplist, list) { + u32 insn; + + 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); + insn = aarch64_insn_gen_branch_imm((unsigned long)op->kp.addr, + (unsigned long)op->optinsn.insn, + AARCH64_INSN_BRANCH_NOLINK); + + WARN_ON(insn == 0); + + aarch64_insn_patch_text((void *)&(op->kp.addr), &insn, 1); + + list_del_init(&op->list); + } +} + +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; + + list_for_each_entry_safe(op, tmp, oplist, list) { + arch_unoptimize_kprobe(op); + list_move(&op->list, done_list); + } +} + +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 0000000..95d1529 --- /dev/null +++ b/arch/arm64/kernel/probes/optprobe_trampoline.S @@ -0,0 +1,81 @@ +/* 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 + stp x0, x1, [sp, #S_X0] + stp x2, x3, [sp, #S_X2] + stp x4, x5, [sp, #S_X4] + stp x6, x7, [sp, #S_X6] + stp x8, x9, [sp, #S_X8] + stp x10, x11, [sp, #S_X10] + stp x12, x13, [sp, #S_X12] + stp x14, x15, [sp, #S_X14] + stp x16, x17, [sp, #S_X16] + stp x18, x19, [sp, #S_X18] + stp x20, x21, [sp, #S_X20] + stp x22, x23, [sp, #S_X22] + stp x24, x25, [sp, #S_X24] + stp x26, x27, [sp, #S_X26] + stp x28, x29, [sp, #S_X28] + add x0, sp, #PT_REGS_SIZE + stp lr, x0, [sp, #S_LR] + /* + * Construct a useful saved PSTATE + */ + mrs x0, nzcv + mrs x1, daif + orr x0, x0, x1 + mrs x1, CurrentEL + orr x0, x0, x1 + mrs x1, SPSel + orr x0, x0, x1 + stp xzr, x0, [sp, #S_PC] + /* Get parameters to optimized_callback() */ + ldr x0, 1f + mov x1, sp + /* Branch to optimized_callback() */ + .global optprobe_template_call +optprobe_template_call: + nop + /* Restore registers */ + ldr x0, [sp, #S_PSTATE] + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) + msr nzcv, x0 + ldp x0, x1, [sp, #S_X0] + ldp x2, x3, [sp, #S_X2] + ldp x4, x5, [sp, #S_X4] + ldp x6, x7, [sp, #S_X6] + ldp x8, x9, [sp, #S_X8] + ldp x10, x11, [sp, #S_X10] + ldp x12, x13, [sp, #S_X12] + ldp x14, x15, [sp, #S_X14] + ldp x16, x17, [sp, #S_X16] + ldp x18, x19, [sp, #S_X18] + ldp x20, x21, [sp, #S_X20] + ldp x22, x23, [sp, #S_X22] + ldp x24, x25, [sp, #S_X24] + ldp x26, x27, [sp, #S_X26] + ldp x28, x29, [sp, #S_X28] + 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 + -- 2.7.4