Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754777AbbHJGSM (ORCPT ); Mon, 10 Aug 2015 02:18:12 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:63168 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754683AbbHJGSI (ORCPT ); Mon, 10 Aug 2015 02:18:08 -0400 From: Wang Nan To: , CC: , , , , , , , , , , , , Subject: [PATCH 23/27] perf tools: Generate prologue for BPF programs Date: Mon, 10 Aug 2015 06:16:05 +0000 Message-ID: <1439187369-66492-24-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1439187369-66492-1-git-send-email-wangnan0@huawei.com> References: <1439187369-66492-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5532 Lines: 207 This patch generates prologue for each 'struct probe_trace_event' for fetching arguments for BPF programs. After bpf__probe(), iterate over each programs to check whether prologue is required. If none of 'struct perf_probe_event' a program will attach to has at least one argument, simply skip preprocessor hooking. For those who prologue is required, calls bpf__gen_prologue() and paste original instruction after prologue. Signed-off-by: Wang Nan Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Daniel Borkmann Cc: David Ahern Cc: He Kuang Cc: Jiri Olsa Cc: Kaixu Xia Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Zefan Li Cc: pi3orama@163.com Cc: Arnaldo Carvalho de Melo Link: http://lkml.kernel.org/n/1436445342-1402-36-git-send-email-wangnan0@huawei.com --- tools/perf/util/bpf-loader.c | 120 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 119 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c index b5f8d11..52fb211 100644 --- a/tools/perf/util/bpf-loader.c +++ b/tools/perf/util/bpf-loader.c @@ -5,10 +5,13 @@ * Copyright (C) 2015 Huawei Inc. */ +#include #include #include "perf.h" #include "debug.h" #include "bpf-loader.h" +#include "bpf-prologue.h" +#include "llvm-utils.h" #include "probe-event.h" #include "probe-finder.h" #include "llvm-utils.h" @@ -42,6 +45,8 @@ struct bpf_prog_priv { struct perf_probe_event *ppev; struct perf_probe_event pev; }; + bool need_prologue; + struct bpf_insn *insns_buf; }; static void @@ -53,6 +58,7 @@ bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused, /* check if pev is initialized */ if (priv && priv->pev_ready) clear_perf_probe_event(&priv->pev); + zfree(&priv->insns_buf); free(priv); } @@ -225,6 +231,103 @@ int bpf__unprobe(void) return ret < 0 ? ret : 0; } +static int +preproc_gen_prologue(struct bpf_program *prog, int n, + struct bpf_insn *orig_insns, int orig_insns_cnt, + struct bpf_prog_prep_result *res) +{ + struct probe_trace_event *tev; + struct perf_probe_event *pev; + struct bpf_prog_priv *priv; + struct bpf_insn *buf; + size_t prologue_cnt = 0; + int err; + + err = bpf_program__get_private(prog, (void **)&priv); + if (err || !priv || !priv->pev_ready) + goto errout; + + pev = &priv->pev; + + if (n < 0 || n >= pev->ntevs) + goto errout; + + tev = &pev->tevs[n]; + + buf = priv->insns_buf; + err = bpf__gen_prologue(tev->args, tev->nargs, + buf, &prologue_cnt, + BPF_MAXINSNS - orig_insns_cnt); + if (err) { + const char *title; + + title = bpf_program__title(prog, false); + if (!title) + title = "??"; + + pr_debug("Failed to generate prologue for program %s\n", + title); + return err; + } + + memcpy(&buf[prologue_cnt], orig_insns, + sizeof(struct bpf_insn) * orig_insns_cnt); + + res->new_insn_ptr = buf; + res->new_insn_cnt = prologue_cnt + orig_insns_cnt; + res->pfd = NULL; + return 0; + +errout: + pr_debug("Internal error in preproc_gen_prologue\n"); + return -EINVAL; +} + +static int hook_load_preprocessor(struct bpf_program *prog) +{ + struct perf_probe_event *pev; + struct bpf_prog_priv *priv; + bool need_prologue = false; + int err, i; + + err = bpf_program__get_private(prog, (void **)&priv); + if (err || !priv) { + pr_debug("Internal error when hook preprocessor\n"); + return -EINVAL; + } + + pev = &priv->pev; + for (i = 0; i < pev->ntevs; i++) { + struct probe_trace_event *tev = &pev->tevs[i]; + + if (tev->nargs > 0) { + need_prologue = true; + break; + } + } + + /* + * Since all tev doesn't have argument, we don't need generate + * prologue. + */ + if (!need_prologue) { + priv->need_prologue = false; + return 0; + } + + priv->need_prologue = true; + priv->insns_buf = malloc(sizeof(struct bpf_insn) * + BPF_MAXINSNS); + if (!priv->insns_buf) { + pr_debug("No enough memory: alloc insns_buf failed\n"); + return -ENOMEM; + } + + err = bpf_program__set_prep(prog, pev->ntevs, + preproc_gen_prologue); + return err; +} + int bpf__probe(void) { int err, nr_events = 0; @@ -275,6 +378,17 @@ int bpf__probe(void) err = sync_bpf_program_pev(prog); if (err) goto out; + /* + * After probing, let's consider prologue, which + * adds program fetcher to BPF programs. + * + * hook_load_preprocessorr() hooks pre-processor + * to bpf_program, let it generate prologue + * dynamically during loading. + */ + err = hook_load_preprocessor(prog); + if (err) + goto out; } } out: @@ -329,7 +443,11 @@ int bpf__foreach_tev(bpf_prog_iter_callback_t func, void *arg) for (i = 0; i < pev->ntevs; i++) { tev = &pev->tevs[i]; - fd = bpf_program__fd(prog); + if (priv->need_prologue) + fd = bpf_program__nth_fd(prog, i); + else + fd = bpf_program__fd(prog); + if (fd < 0) { pr_debug("bpf: failed to get file descriptor\n"); return fd; -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/