Messages in this thread Patch in this message | | | From | Janet Liu <> | Subject | [PATCH v1 2/2] arm64: kprobes: add support for KPROBES_ON_FTRACE | Date | Fri, 29 Oct 2021 20:27:45 +0800 |
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From: Janet Liu <janet.liu@unisoc.com>
This patch allow kprobes on ftrace call sites. This optimization avoids use of a trap with regular kprobes.
This depends on HAVE_DYNAMIC_FTRACE_WITH_REGS which depends on "patchable-function-entry" options which is only implemented with newer toolchains.
Signed-off-by: Janet Liu <janet.liu@unisoc.com> --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/probes/Makefile | 1 + arch/arm64/kernel/probes/ftrace.c | 73 ++++++++++++++++++++++++++++++++++++++ arch/arm64/kernel/probes/kprobes.c | 27 ++++++++++++++ 4 files changed, 102 insertions(+) create mode 100644 arch/arm64/kernel/probes/ftrace.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index ab07251..c3fd0dd 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -200,6 +200,7 @@ config ARM64 select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES select HAVE_OPTPROBES + select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES select HAVE_GENERIC_VDSO select IOMMU_DMA if IOMMU_SUPPORT diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile index c77c92a..d9b204f 100644 --- a/arch/arm64/kernel/probes/Makefile +++ b/arch/arm64/kernel/probes/Makefile @@ -3,5 +3,6 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \ kprobes_trampoline.o \ simulate-insn.o obj-$(CONFIG_OPTPROBES) += opt.o opt_head.o +obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \ simulate-insn.o diff --git a/arch/arm64/kernel/probes/ftrace.c b/arch/arm64/kernel/probes/ftrace.c new file mode 100644 index 0000000..46ea92e --- /dev/null +++ b/arch/arm64/kernel/probes/ftrace.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0-only +// +// Dynamic Ftrace based Kprobes Optimization +// +// Copyright (C) 2021, Unisoc Inc. +// Author: Janet Liu <janet.liu@unisoc.com> +#include <linux/kprobes.h> +#include <linux/ptrace.h> +#include <linux/hardirq.h> +#include <linux/preempt.h> +#include <linux/ftrace.h> + + +/* Ftrace callback handler for kprobes*/ +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct ftrace_regs *fregs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + struct pt_regs *regs = ftrace_get_regs(fregs); + int bit; + + bit = ftrace_test_recursion_trylock(ip, parent_ip); + if (bit < 0) + return; + + preempt_disable_notrace(); + p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(!p) || kprobe_disabled(p)) + goto end; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_ip = instruction_pointer(regs); + + instruction_pointer_set(regs, ip); + + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (!p->pre_handler || !p->pre_handler(p, regs)) { + /* + *Emulate singlestep (and also recover regs->pc) + *as if there is a nop + */ + instruction_pointer_set(regs, + (unsigned long)p->addr + MCOUNT_INSN_SIZE); + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + instruction_pointer_set(regs, orig_ip); + } + + /* + * If pre_handler returns !0,it changes regs->pc. We have to + * skip emulating post_handler. + */ + __this_cpu_write(current_kprobe, NULL); + } +end: + preempt_enable_notrace(); + ftrace_test_recursion_unlock(bit); +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn = NULL; + p->ainsn.api.restore = 0; + return 0; +} diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 6dbcc89..3d371d3 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -417,6 +417,33 @@ int __kprobes arch_trampoline_kprobe(struct kprobe *p) return 0; } +kprobe_opcode_t __kprobes *kprobe_lookup_name(const char *name, unsigned int offset) +{ + kprobe_opcode_t *addr; + + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); +#ifdef CONFIG_KPROBES_ON_FTRACE + if (addr && !offset) { + unsigned long faddr; + + faddr = ftrace_location_range((unsigned long)addr, + (unsigned long)addr + 8); + if (faddr) + addr = (kprobe_opcode_t *)faddr; + } +#endif + return addr; +} + +bool __kprobes arch_kprobe_on_func_entry(unsigned long offset) +{ +#ifdef CONFIG_KPROBES_ON_FTRACE + return offset <= 8; +#else + return !offset; +#endif +} + int __init arch_init_kprobes(void) { register_kernel_break_hook(&kprobes_break_hook); -- 1.9.1
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