Messages in this thread Patch in this message | | | From | Cheng Jian <> | Subject | [PATCH] arm64/kprobe: add support for KPROBES_ON_FTRACE | Date | Mon, 23 Dec 2019 12:38:28 +0000 |
| |
Allow KPROBES to use the ftrace infrastructure. This depends on HAVE_DYNAMIC_FTRACE_WITH_REGS which introduce by : commit 3b23e4991fb6 ("arm64: implement ftrace with regs")
Based on the x86 code by Masami.
With: # cd /sys/kernel/debug/tracing # echo 'p _do_fork+0x4' > kprobe_events
before patch: # cat ../kprobes/list sh: write error: Invalid argument
after patch: # cat ../kprobes/list ffffa00016aa9d4c k _do_fork+0x4 [FTRACE]
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> --- .../debug/kprobes-on-ftrace/arch-support.txt | 2 +- arch/arm64/Kconfig | 1 + arch/arm64/kernel/probes/Makefile | 2 + arch/arm64/kernel/probes/ftrace.c | 65 +++++++++++++++++++ 4 files changed, 69 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/probes/ftrace.c
diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt index 4fae0464ddff..f9dd9dd91e0c 100644 --- a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt +++ b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt @@ -9,7 +9,7 @@ | alpha: | TODO | | arc: | TODO | | arm: | TODO | - | arm64: | TODO | + | arm64: | ok | | c6x: | TODO | | csky: | TODO | | h8300: | TODO | diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b1b4476ddb83..d613be9c2346 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -144,6 +144,7 @@ config ARM64 select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_REGS \ if $(cc-option,-fpatchable-function-entry=2) + select HAVE_KPROBES_ON_FTRACE if HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_FAST_GUP select HAVE_FTRACE_MCOUNT_RECORD diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile index 8e4be92e25b1..45a9d916a47d 100644 --- a/arch/arm64/kernel/probes/Makefile +++ b/arch/arm64/kernel/probes/Makefile @@ -4,3 +4,5 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \ simulate-insn.o obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \ simulate-insn.o + +obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o diff --git a/arch/arm64/kernel/probes/ftrace.c b/arch/arm64/kernel/probes/ftrace.c new file mode 100644 index 000000000000..f89bfaa3e5f3 --- /dev/null +++ b/arch/arm64/kernel/probes/ftrace.c @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Dynamic Ftrace based Kprobes Optimization + * + * Copyright (C) Hitachi Ltd., 2012 + * Copyright (C) 2019 Huawei Inc. + * Copyright 2019 Cheng Jian <cj.chengjian@huawei.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 -- called under preepmt disabed */ +void kprobe_ftrace_handler(unsigned long pc, unsigned long parent_pc, + struct ftrace_ops *ops, struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + /* Preempt is disabled by ftrace */ + p = get_kprobe((kprobe_opcode_t *)pc); + if (unlikely(!p) || kprobe_disabled(p)) + return; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + /* + * On ARM64, recg->pc is *before* this instruction for the + * pre handler. + */ + regs->pc -= MCOUNT_INSN_SIZE; + + __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->ip) + * as if there is a nop + */ + regs->pc += MCOUNT_INSN_SIZE; + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + } + /* + * If pre_handler returns !0, it changes regs->ip. We have to + * skip emulating post_handler. + */ + __this_cpu_write(current_kprobe, NULL); + } +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn = NULL; + + return 0; +} -- 2.17.1
| |