From patchwork Tue Nov 1 05:23:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13518 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:6687:0:0:0:0:0 with SMTP id l7csp2748104wru; Mon, 31 Oct 2022 22:27:15 -0700 (PDT) X-Google-Smtp-Source: AMsMyM7Ll1RClTFJssr71TiMH64ROqKsK5QyFg328I6STGzvAWSl9di7ZRX9QcxVRGig2hNvI2RQ X-Received: by 2002:a17:906:ee88:b0:78d:1a9a:b2db with SMTP id wt8-20020a170906ee8800b0078d1a9ab2dbmr16815395ejb.225.1667280435318; Mon, 31 Oct 2022 22:27:15 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1667280435; cv=none; d=google.com; s=arc-20160816; b=YPBXYN2Xm23yZtjAN6gAPL/bECns6N5o4cLuOUY1GC7BuaLILbdrWhvXchxxI+9eSX HwXotNbuLl+k2Nkptu2UMwIVZqiYsqKv3IJACaWHbakgu5rAncAVCx8a/wo8Mwk/RqsA FXKt+fWPiryt1eJ7yPR9+dwzAyEtui6j4vuv6H8QilqClohnPmwnGeK5Gf4D6GwAQ/rO Sv3ZYVtrefNYnVfhCcZTppn/Eat7J17uS35cMQm2wfh188etUkqKKGEwrpsdpytzo8fm DCW4zMVPxJhtRF3dcUjR8Cnj7FfVL+RaBSn9cSlnFEkCpY7rUopn+S9/l+3UwX1GvocF U8gA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from:sender :dkim-signature; bh=US7eYoRgQfEJ8iwJ/HYz2Irbm2/CnXBZTSFBhyzNSKU=; b=0JExYLYI7ute8tO/TaoKktHr5E2s7tp+itlIHvHPEYLboVQ2yXjtgh2IxfIInrW5/b FcEEE1aGeUj5CrMHmr/7g+mB8pGXsceTFCzWKsrHqOoC09AAy7P04O+yaSyNkxzavD6h gqpXk2khljM7dkCBOpvachyD3PbaGqJY+7SLW3VaFabm/eHJAbOw5pTpf0ihGE/5LUao BkMNRZbbaeYr2o8cGGV77a71gObYsBHDv+39EiabbywOivkMG6w86rHvSsWO1e3ok+EV YJjNF2rfPP1SmQ7KY43feYJxajH5mWR4SuBKhs17KvuVMBPvudyzkB9KwP7bf0AaGmJK VHcQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=TwB435Oq; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (out1.vger.email. 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I'm taking a conservative approach to allow a list of sample formats only instead of allowing them all. For now, IP and ADDR data are allowed and I think it's good enough to build and verify general BPF-based sample filters for perf events. Signed-off-by: Namhyung Kim --- kernel/events/core.c | 40 +++++++++++++++++++++++++++++++--------- 1 file changed, 31 insertions(+), 9 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index aefc1e08e015..519f30c33a24 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7329,8 +7329,10 @@ void perf_prepare_sample(struct perf_event_header *header, filtered_sample_type = sample_type & ~data->sample_flags; __perf_event_header__init_id(header, data, event, filtered_sample_type); - if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE)) - data->ip = perf_instruction_pointer(regs); + if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE)) { + if (filtered_sample_type & PERF_SAMPLE_IP) + data->ip = perf_instruction_pointer(regs); + } if (sample_type & PERF_SAMPLE_CALLCHAIN) { int size = 1; @@ -10006,6 +10008,32 @@ static void perf_event_free_filter(struct perf_event *event) } #ifdef CONFIG_BPF_SYSCALL +static void bpf_prepare_sample(struct bpf_prog *prog, + struct perf_event *event, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + u64 filtered_sample_type; + + filtered_sample_type = event->attr.sample_type & ~data->sample_flags; + + if (prog->call_get_stack && + (filtered_sample_type & PERF_SAMPLE_CALLCHAIN)) { + data->callchain = perf_callchain(event, regs); + data->sample_flags |= PERF_SAMPLE_CALLCHAIN; + } + + if (filtered_sample_type & PERF_SAMPLE_IP) { + data->ip = perf_instruction_pointer(regs); + data->sample_flags |= PERF_SAMPLE_IP; + } + + if (filtered_sample_type & PERF_SAMPLE_ADDR) { + data->addr = 0; + data->sample_flags |= PERF_SAMPLE_ADDR; + } +} + static void bpf_overflow_handler(struct perf_event *event, struct perf_sample_data *data, struct pt_regs *regs) @@ -10023,13 +10051,7 @@ static void bpf_overflow_handler(struct perf_event *event, rcu_read_lock(); prog = READ_ONCE(event->prog); if (prog) { - if (prog->call_get_stack && - (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) && - !(data->sample_flags & PERF_SAMPLE_CALLCHAIN)) { - data->callchain = perf_callchain(event, regs); - data->sample_flags |= PERF_SAMPLE_CALLCHAIN; - } - + bpf_prepare_sample(prog, event, data, regs); ret = bpf_prog_run(prog, &ctx); } rcu_read_unlock(); From patchwork Tue Nov 1 05:23:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13517 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:6687:0:0:0:0:0 with SMTP id l7csp2747539wru; Mon, 31 Oct 2022 22:25:50 -0700 (PDT) X-Google-Smtp-Source: AMsMyM6KXduS3wQKqJqTJBKaTJ9+rSmzyBtkoLuPs690qxICQLjsxIjHOUQFaiT5/yOl0VoX/W99 X-Received: by 2002:a05:6402:2994:b0:453:4c5c:d31c with SMTP id eq20-20020a056402299400b004534c5cd31cmr17194720edb.412.1667280350668; Mon, 31 Oct 2022 22:25:50 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1667280350; cv=none; d=google.com; s=arc-20160816; b=LSPscWfieAic/G3JGCPBhfpdDXFtd+hVASrCSh5no9qer5QG3B3Mvlxcv3uexMvITU JhB0XNjuIjUo7wk+xNSVJfmX/JDNDAyNZB/o6QtPn5QApeE+XshyOyMRfotoolE18zXy nxWyYHyQtTr5Mz++oSyluLhDruziEwfOTxqxA81idooe9WBUGwzgihEFsNzSwL7VW73w qIfAMxtZqocYa00Jo9TgPZsdRvwqo89pJFKD9dkATtrBUWMC8Adq/EYSfJYsE+xOM9JQ 3lnAAn+vY3U38wSqYoKApFGz7S2yb7CWamfVX2/1VgYaVpdahtj1N8O3jt54LQe5Zbcr S5ow== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from:sender :dkim-signature; bh=oCQ6m+iiPPfCEHc1DMVvUTpMxY5WVNF+ufmtjL4sYpE=; b=npzgb6DNJ4HKfJctoAxjnRWvKUmm6XQt2hQ9IP7n8dtt9Sy7bQOBW+lcAcEXanDfxR YwMEf51ImXx8PdwoUkFuNUEX8RsYH7oBLpRBHlyUABL2AWqBdZT/p2cYLr38lhk4x6Dd zjLtR/yu6+K4M6Ugy3HeYkv0asLyaw91mclMwE3PpfkyU/XsEr/uivM6vqIA81nXOljZ ZaBjwuVc84SIOLrAzv1sra+3zJ8mVGQ5q4NHNI+xBPw4npK/uGu+likm8g+xUcVbYQWm rZW0gDCcSjJ52oqYuAcoMtQ2MM89Q3Dy58Rnb9o/Tb5L6I9a3kAZFpnUQQ+k8ETOYUMd mfuA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b="BTX/s0xI"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (out1.vger.email. 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The BPF program can control sample data using the return value after checking the sample data and size. Signed-off-by: Namhyung Kim --- .../selftests/bpf/prog_tests/perf_sample.c | 172 ++++++++++++++++++ .../selftests/bpf/progs/test_perf_sample.c | 28 +++ 2 files changed, 200 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_sample.c create mode 100644 tools/testing/selftests/bpf/progs/test_perf_sample.c diff --git a/tools/testing/selftests/bpf/prog_tests/perf_sample.c b/tools/testing/selftests/bpf/prog_tests/perf_sample.c new file mode 100644 index 000000000000..eee11f23196c --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/perf_sample.c @@ -0,0 +1,172 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include + +#include +#include "test_perf_sample.skel.h" + +#ifndef noinline +#define noinline __attribute__((noinline)) +#endif + +/* treat user-stack data as invalid (for testing only) */ +#define PERF_SAMPLE_INVALID PERF_SAMPLE_STACK_USER + +#define PERF_MMAP_SIZE 8192 +#define DATA_MMAP_SIZE 4096 + +static int perf_fd = -1; +static void *perf_ringbuf; +static struct test_perf_sample *skel; + +static int open_perf_event(u64 sample_flags) +{ + struct perf_event_attr attr = { + .type = PERF_TYPE_SOFTWARE, + .config = PERF_COUNT_SW_PAGE_FAULTS, + .sample_type = sample_flags, + .sample_period = 1, + .disabled = 1, + .size = sizeof(attr), + }; + int fd; + void *ptr; + + fd = syscall(SYS_perf_event_open, &attr, 0, -1, -1, 0); + if (!ASSERT_GT(fd, 0, "perf_event_open")) + return -1; + + ptr = mmap(NULL, PERF_MMAP_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); + if (!ASSERT_NEQ(ptr, MAP_FAILED, "mmap")) { + close(fd); + return -1; + } + + perf_fd = fd; + perf_ringbuf = ptr; + + return 0; +} + +static void close_perf_event(void) +{ + if (perf_fd == -1) + return; + + munmap(perf_ringbuf, PERF_MMAP_SIZE); + close(perf_fd); + + perf_fd = -1; + perf_ringbuf = NULL; +} + +static noinline void trigger_perf_event(void) +{ + int *buf = mmap(NULL, DATA_MMAP_SIZE, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0); + + if (!ASSERT_NEQ(buf, MAP_FAILED, "mmap")) + return; + + ioctl(perf_fd, PERF_EVENT_IOC_ENABLE); + + /* it should generate a page fault which triggers the perf_event */ + *buf = 1; + + ioctl(perf_fd, PERF_EVENT_IOC_DISABLE); + + munmap(buf, DATA_MMAP_SIZE); +} + +/* check if the perf ringbuf has a sample data */ +static int check_perf_event(void) +{ + struct perf_event_mmap_page *page = perf_ringbuf; + struct perf_event_header *hdr; + + if (page->data_head == page->data_tail) + return 0; + + hdr = perf_ringbuf + page->data_offset; + + if (hdr->type != PERF_RECORD_SAMPLE) + return 0; + + return 1; +} + +static void setup_perf_sample_bpf_skel(u64 sample_flags) +{ + struct bpf_link *link; + + skel = test_perf_sample__open_and_load(); + if (!ASSERT_OK_PTR(skel, "test_perf_sample_open_and_load")) + return; + + skel->bss->sample_flag = sample_flags; + skel->bss->sample_size = sizeof(sample_flags); + + link = bpf_program__attach_perf_event(skel->progs.perf_sample_filter, perf_fd); + if (!ASSERT_OK_PTR(link, "bpf_program__attach_perf_event")) + return; +} + +static void clean_perf_sample_bpf_skel(void) +{ + test_perf_sample__detach(skel); + test_perf_sample__destroy(skel); +} + +static void test_perf_event_read_sample_invalid(void) +{ + u64 flags = PERF_SAMPLE_INVALID; + + if (open_perf_event(flags) < 0) + return; + setup_perf_sample_bpf_skel(flags); + trigger_perf_event(); + ASSERT_EQ(check_perf_event(), 0, "number of sample"); + clean_perf_sample_bpf_skel(); + close_perf_event(); +} + +static void test_perf_event_read_sample_ip(void) +{ + u64 flags = PERF_SAMPLE_IP; + + if (open_perf_event(flags) < 0) + return; + setup_perf_sample_bpf_skel(flags); + trigger_perf_event(); + ASSERT_EQ(check_perf_event(), 1, "number of sample"); + clean_perf_sample_bpf_skel(); + close_perf_event(); +} + +static void test_perf_event_read_sample_addr(void) +{ + u64 flags = PERF_SAMPLE_ADDR; + + if (open_perf_event(flags) < 0) + return; + setup_perf_sample_bpf_skel(flags); + trigger_perf_event(); + ASSERT_EQ(check_perf_event(), 1, "number of sample"); + clean_perf_sample_bpf_skel(); + close_perf_event(); +} + +void test_perf_event_read_sample(void) +{ + if (test__start_subtest("perf_event_read_sample_invalid")) + test_perf_event_read_sample_invalid(); + if (test__start_subtest("perf_event_read_sample_ip")) + test_perf_event_read_sample_ip(); + if (test__start_subtest("perf_event_read_sample_addr")) + test_perf_event_read_sample_addr(); +} diff --git a/tools/testing/selftests/bpf/progs/test_perf_sample.c b/tools/testing/selftests/bpf/progs/test_perf_sample.c new file mode 100644 index 000000000000..79664acafcd9 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_perf_sample.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2022 Google + +#include +#include +#include + +unsigned long long sample_flag; +unsigned long long sample_size; + +SEC("perf_event") +int perf_sample_filter(void *ctx) +{ + long size; + unsigned long long buf[1] = {}; + + size = bpf_perf_event_read_sample(ctx, NULL, 0, sample_flag); + if (size != sample_size) + return 0; + + if (bpf_perf_event_read_sample(ctx, buf, sizeof(buf), sample_flag) < 0) + return 0; + + /* generate sample data */ + return 1; +} + +char _license[] SEC("license") = "GPL";