From patchwork Wed Aug 16 16:35:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Francis Laniel X-Patchwork-Id: 13355475 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 668A8C41513 for ; Wed, 16 Aug 2023 16:36:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344738AbjHPQfs (ORCPT ); Wed, 16 Aug 2023 12:35:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344752AbjHPQfn (ORCPT ); Wed, 16 Aug 2023 12:35:43 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DAF45199B; Wed, 16 Aug 2023 09:35:41 -0700 (PDT) Received: from pwmachine.numericable.fr (85-170-34-233.rev.numericable.fr [85.170.34.233]) by linux.microsoft.com (Postfix) with ESMTPSA id 4632F211F614; Wed, 16 Aug 2023 09:35:40 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4632F211F614 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1692203741; bh=ElFNTE62wAoAri3uxF0HbO1j0BAyiEyFTr89HUlnOwE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HqSc3sFVgYM/NnhDRNIVNvOC4OVMb4rZPiLIty2CamJCEjsNQ2viGjE9TaTl86ppz OtJJZxg9FJVnkdbrH8cIAHG93RNUCZm4r0DHafT4l3oCuhMP7/wkWbY0owpKv5QUZY TjtIALQscvAt7Wswq03bv0FlY4kcFGzu3jfHecN4= From: Francis Laniel To: linux-kernel@vger.kernel.org Cc: Francis Laniel , Steven Rostedt , Masami Hiramatsu , linux-trace-kernel@vger.kernel.org Subject: [RFC PATCH v1 1/1] tracing/kprobe: Add multi-probe support for 'perf_kprobe' PMU Date: Wed, 16 Aug 2023 18:35:17 +0200 Message-Id: <20230816163517.112518-2-flaniel@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230816163517.112518-1-flaniel@linux.microsoft.com> References: <20230816163517.112518-1-flaniel@linux.microsoft.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org When using sysfs, it is possible to create kprobe for several kernel functions sharing the same name, but of course with different addresses, by writing their addresses in kprobe_events file. When using PMU, if only the symbol name is given, the event will be created for the first address which matches the symbol, as returned by kallsyms_lookup_name(). The idea here is to search all kernel functions which match this symbol and create a trace_kprobe for each of them. All these trace_kprobes are linked together by sharing the same trace_probe. Signed-off-by: Francis Laniel --- kernel/trace/trace_kprobe.c | 86 +++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 1b3fa7b854aa..08580f1466c7 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1682,13 +1682,42 @@ static int unregister_kprobe_event(struct trace_kprobe *tk) } #ifdef CONFIG_PERF_EVENTS + +struct address_array { + unsigned long *addrs; + size_t size; +}; + +static int add_addr(void *data, unsigned long addr) +{ + struct address_array *array = data; + unsigned long *p; + + array->size++; + p = krealloc(array->addrs, + sizeof(*array->addrs) * array->size, + GFP_KERNEL); + if (!p) { + kfree(array->addrs); + return -ENOMEM; + } + + array->addrs = p; + array->addrs[array->size - 1] = addr; + + return 0; +} + /* create a trace_kprobe, but don't add it to global lists */ struct trace_event_call * create_local_trace_kprobe(char *func, void *addr, unsigned long offs, bool is_return) { enum probe_print_type ptype; + struct address_array array; struct trace_kprobe *tk; + unsigned long func_addr; + unsigned int i; int ret; char *event; @@ -1722,7 +1751,64 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs, if (ret < 0) goto error; + array.addrs = NULL; + array.size = 0; + ret = kallsyms_on_each_match_symbol(add_addr, func, &array); + if (ret) + goto error_free; + + if (array.size == 1) + goto end; + + /* + * Below loop allocates a trace_kprobe for each function with the same + * name in kernel source code. + * All this differente trace_kprobes will be linked together through + * append_trace_kprobe(). + * NOTE append_trace_kprobe() is called in register_trace_kprobe() which + * is called when a kprobe is added through sysfs. + */ + func_addr = kallsyms_lookup_name(func); + for (i = 0; i < array.size; i++) { + struct trace_kprobe *tk_same_name; + unsigned long address; + + address = array.addrs[i]; + /* Skip the function address as we already registered it. */ + if (address == func_addr) + continue; + + /* + * alloc_trace_kprobe() first considers symbol name, so we set + * this to NULL to allocate this kprobe on the given address. + */ + tk_same_name = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, + (void *)address, NULL, offs, + 0 /* maxactive */, + 0 /* nargs */, is_return); + + if (IS_ERR(tk_same_name)) { + ret = -ENOMEM; + goto error_free; + } + + init_trace_event_call(tk_same_name); + + if (traceprobe_set_print_fmt(&tk_same_name->tp, ptype) < 0) { + ret = -ENOMEM; + goto error_free; + } + + ret = append_trace_kprobe(tk_same_name, tk); + if (ret) + goto error_free; + } + +end: + kfree(array.addrs); return trace_probe_event_call(&tk->tp); +error_free: + kfree(array.addrs); error: free_trace_kprobe(tk); return ERR_PTR(ret);