Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965456AbeAJKRf (ORCPT + 1 other); Wed, 10 Jan 2018 05:17:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:51156 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751689AbeAJKRb (ORCPT ); Wed, 10 Jan 2018 05:17:31 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45AB921724 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mhiramat@kernel.org From: Masami Hiramatsu To: Alexei Starovoitov , Josef Bacik Cc: rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org, kernel-team@fb.com, daniel@iogearbox.net, linux-btrfs@vger.kernel.org, darrick.wong@oracle.com, mhiramat@kernel.org, Josef Bacik , Akinobu Mita Subject: [PATCH bpf-next v3 1/5] tracing/kprobe: bpf: Check error injectable event is on function entry Date: Wed, 10 Jan 2018 19:17:06 +0900 Message-Id: <151557942619.6629.4941380220602441478.stgit@devbox> X-Mailer: git-send-email 2.13.6 In-Reply-To: <151557939382.6629.18074658376309258555.stgit@devbox> References: <151557939382.6629.18074658376309258555.stgit@devbox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Check whether error injectable event is on function entry or not. Currently it checks the event is ftrace-based kprobes or not, but that is wrong. It should check if the event is on the entry of target function. Since error injection will override a function to just return with modified return value, that operation must be done before the target function starts making stackframe. As a side effect, bpf error injection is no need to depend on function-tracer. It can work with sw-breakpoint based kprobe events too. Signed-off-by: Masami Hiramatsu --- Changes in v3: - Move arch_ftrace_kprobe_override_function() to core.c because it is no longer depending on ftrace. - Fix a bug to skip passing kprobes target name to kprobe_on_func_entry(). Passing both @addr and @symbol to that function will result in failure. --- arch/x86/include/asm/kprobes.h | 4 +--- arch/x86/kernel/kprobes/core.c | 14 ++++++++++++++ arch/x86/kernel/kprobes/ftrace.c | 14 -------------- kernel/trace/Kconfig | 2 -- kernel/trace/bpf_trace.c | 8 ++++---- kernel/trace/trace_kprobe.c | 9 ++++++--- kernel/trace/trace_probe.h | 12 ++++++------ 7 files changed, 31 insertions(+), 32 deletions(-) diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h index 36abb23a7a35..367d99cff426 100644 --- a/arch/x86/include/asm/kprobes.h +++ b/arch/x86/include/asm/kprobes.h @@ -67,9 +67,7 @@ extern const int kretprobe_blacklist_size; void arch_remove_kprobe(struct kprobe *p); asmlinkage void kretprobe_trampoline(void); -#ifdef CONFIG_KPROBES_ON_FTRACE -extern void arch_ftrace_kprobe_override_function(struct pt_regs *regs); -#endif +extern void arch_kprobe_override_function(struct pt_regs *regs); /* Architecture specific copy of original instruction*/ struct arch_specific_insn { diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index bd36f3c33cd0..b02a377d5905 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -1183,3 +1183,17 @@ int arch_trampoline_kprobe(struct kprobe *p) { return 0; } + +asmlinkage void override_func(void); +asm( + ".type override_func, @function\n" + "override_func:\n" + " ret\n" + ".size override_func, .-override_func\n" +); + +void arch_kprobe_override_function(struct pt_regs *regs) +{ + regs->ip = (unsigned long)&override_func; +} +NOKPROBE_SYMBOL(arch_kprobe_override_function); diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c index 1ea748d682fd..8dc0161cec8f 100644 --- a/arch/x86/kernel/kprobes/ftrace.c +++ b/arch/x86/kernel/kprobes/ftrace.c @@ -97,17 +97,3 @@ int arch_prepare_kprobe_ftrace(struct kprobe *p) p->ainsn.boostable = false; return 0; } - -asmlinkage void override_func(void); -asm( - ".type override_func, @function\n" - "override_func:\n" - " ret\n" - ".size override_func, .-override_func\n" -); - -void arch_ftrace_kprobe_override_function(struct pt_regs *regs) -{ - regs->ip = (unsigned long)&override_func; -} -NOKPROBE_SYMBOL(arch_ftrace_kprobe_override_function); diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index ae3a2d519e50..6400e1bf97c5 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -533,9 +533,7 @@ config FUNCTION_PROFILER config BPF_KPROBE_OVERRIDE bool "Enable BPF programs to override a kprobed function" depends on BPF_EVENTS - depends on KPROBES_ON_FTRACE depends on HAVE_KPROBE_OVERRIDE - depends on DYNAMIC_FTRACE_WITH_REGS default n help Allows BPF to override the execution of a probed function and diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index f6d2327ecb59..1966ad3bf3e0 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -85,7 +85,7 @@ BPF_CALL_2(bpf_override_return, struct pt_regs *, regs, unsigned long, rc) { __this_cpu_write(bpf_kprobe_override, 1); regs_set_return_value(regs, rc); - arch_ftrace_kprobe_override_function(regs); + arch_kprobe_override_function(regs); return 0; } @@ -800,11 +800,11 @@ int perf_event_attach_bpf_prog(struct perf_event *event, int ret = -EEXIST; /* - * Kprobe override only works for ftrace based kprobes, and only if they - * are on the opt-in list. + * Kprobe override only works if they are on the function entry, + * and only if they are on the opt-in list. */ if (prog->kprobe_override && - (!trace_kprobe_ftrace(event->tp_event) || + (!trace_kprobe_on_func_entry(event->tp_event) || !trace_kprobe_error_injectable(event->tp_event))) return -EINVAL; diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 91f4b57dab82..3c8deb977a8b 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -88,13 +88,16 @@ static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk) return nhit; } -int trace_kprobe_ftrace(struct trace_event_call *call) +bool trace_kprobe_on_func_entry(struct trace_event_call *call) { struct trace_kprobe *tk = (struct trace_kprobe *)call->data; - return kprobe_ftrace(&tk->rp.kp); + + return kprobe_on_func_entry(tk->rp.kp.addr, + tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name, + tk->rp.kp.addr ? 0 : tk->rp.kp.offset); } -int trace_kprobe_error_injectable(struct trace_event_call *call) +bool trace_kprobe_error_injectable(struct trace_event_call *call) { struct trace_kprobe *tk = (struct trace_kprobe *)call->data; unsigned long addr; diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 5e54d748c84c..e101c5bb9eda 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -252,8 +252,8 @@ struct symbol_cache; unsigned long update_symbol_cache(struct symbol_cache *sc); void free_symbol_cache(struct symbol_cache *sc); struct symbol_cache *alloc_symbol_cache(const char *sym, long offset); -int trace_kprobe_ftrace(struct trace_event_call *call); -int trace_kprobe_error_injectable(struct trace_event_call *call); +bool trace_kprobe_on_func_entry(struct trace_event_call *call); +bool trace_kprobe_error_injectable(struct trace_event_call *call); #else /* uprobes do not support symbol fetch methods */ #define fetch_symbol_u8 NULL @@ -280,14 +280,14 @@ alloc_symbol_cache(const char *sym, long offset) return NULL; } -static inline int trace_kprobe_ftrace(struct trace_event_call *call) +static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call) { - return 0; + return false; } -static inline int trace_kprobe_error_injectable(struct trace_event_call *call) +static inline bool trace_kprobe_error_injectable(struct trace_event_call *call) { - return 0; + return false; } #endif /* CONFIG_KPROBE_EVENTS */