From patchwork Thu Mar 10 08:22:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 12776022 X-Patchwork-Delegate: bpf@iogearbox.net 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 B8C3EC433FE for ; Thu, 10 Mar 2022 08:22:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239191AbiCJIXL (ORCPT ); Thu, 10 Mar 2022 03:23:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234545AbiCJIXJ (ORCPT ); Thu, 10 Mar 2022 03:23:09 -0500 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74D9899698; Thu, 10 Mar 2022 00:22:08 -0800 (PST) Received: by mail-pj1-x1034.google.com with SMTP id 15-20020a17090a098f00b001bef0376d5cso4548828pjo.5; Thu, 10 Mar 2022 00:22:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=vxbnybQKpkfay2iHQzcgyktbxlcEBTXr8udywXFflIs=; b=W/3z9Oqdh8/2k2g6SQJMQUoexKyl+RSMUAXa9Zuuya31CAiVULnsn3yGTxZIGoG8ts diUceabMVH9Da0WTMZ7ywZ1qwtG0u43WzVE8RYXfruZQSPZdmsuYbaO0AOA7mqeDRdqg fCbMH1sQ6Ks5lPlROKJ19NzNXpV6MiRW7L0lzScEb32ooKrO/C9hm9eCHeiSXhCWWXZT 13U9NQ//BfS9aKJS6Y9I4Lw+szbi+ikvTgqUECIW4svuQWjhQaOAJEbu+diwWS+2nWYS y0w0oEt+WKWrRw0Orl/CmvTMQ2P9/WRdWGYNGv5Pq0R/wqrvHyxdG9m2aL+1X9il91on oTsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=vxbnybQKpkfay2iHQzcgyktbxlcEBTXr8udywXFflIs=; b=f4xv5G1I2n20kU5kdJx7eflbhvygIX08Jn1UAnS0VMNE6D8xr6FZQYb2VhCP8PcjsV V8om95Na9Qy9qDJvTCvIFuwdCuM9i4SrzqTEmT4RliIQpSZmMoHKJVlcq31HOUY3oBRZ xln4vRqdULvipWoAhD/h5K89eIZ988DLS6yymnsl73dXUQRt2XG5Dd1e8J7lUdcLaKRg LmwR/FLyznYswOWwk+nQFzitD5ZMW5M/17V0Y0pzE+tjOdLl+2ZzLuQL42ZGj9DaNWyU U1NhyKjD13Jm9J7xvUrX31WNQtV0OW56fL/lZeROF2F/id0T1W7vS5dBIr7rhhQF5ndt bogw== X-Gm-Message-State: AOAM5314o+9j2lq3zSON7pu/+/nstz00Cm43wRD4gBJtsndoOIqiNQ6L 9pMzPZDhxazWGCDizXrB8Sw= X-Google-Smtp-Source: ABdhPJzWohQvo5vEKV4hAl68MPDykkWW2muYj8ILf8prnZuxRyRz2xPPkTGxLKnCQNcCkJHxfEZGFw== X-Received: by 2002:a17:90b:384:b0:1bf:cd0f:81b4 with SMTP id ga4-20020a17090b038400b001bfcd0f81b4mr2873148pjb.199.1646900527902; Thu, 10 Mar 2022 00:22:07 -0800 (PST) Received: from balhae.hsd1.ca.comcast.net ([2601:647:4800:3540:e7f1:5749:9be:64e1]) by smtp.gmail.com with ESMTPSA id a12-20020a056a000c8c00b004e1a76f0a8asm5903008pfv.51.2022.03.10.00.22.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Mar 2022 00:22:07 -0800 (PST) Sender: Namhyung Kim From: Namhyung Kim To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org, LKML , Arnaldo Carvalho de Melo , Peter Zijlstra , Eugene Loh , Hao Luo Subject: [PATCH 1/2] bpf: Adjust BPF stack helper functions to accommodate skip > 0 Date: Thu, 10 Mar 2022 00:22:01 -0800 Message-Id: <20220310082202.1229345-1-namhyung@kernel.org> X-Mailer: git-send-email 2.35.1.723.g4982287a31-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Let's say that the caller has storage for num_elem stack frames. Then, the BPF stack helper functions walk the stack for only num_elem frames. This means that if skip > 0, one keeps only 'num_elem - skip' frames. This is because it sets init_nr in the perf_callchain_entry to the end of the buffer to save num_elem entries only. I believe it was because the perf callchain code unwound the stack frames until it reached the global max size (sysctl_perf_event_max_stack). However it now has perf_callchain_entry_ctx.max_stack to limit the iteration locally. This simplifies the code to handle init_nr in the BPF callstack entries and removes the confusion with the perf_event's __PERF_SAMPLE_CALLCHAIN_EARLY which sets init_nr to 0. Also change the comment on bpf_get_stack() in the header file to be more explicit what the return value means. Based-on-patch-by: Eugene Loh Signed-off-by: Namhyung Kim Acked-by: Yonghong Song --- include/uapi/linux/bpf.h | 4 +-- kernel/bpf/stackmap.c | 56 +++++++++++++++++----------------------- 2 files changed, 26 insertions(+), 34 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b0383d371b9a..77f4a022c60c 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2975,8 +2975,8 @@ union bpf_attr { * * # sysctl kernel.perf_event_max_stack= * Return - * A non-negative value equal to or less than *size* on success, - * or a negative error in case of failure. + * The non-negative copied *buf* length equal to or less than + * *size* on success, or a negative error in case of failure. * * long bpf_skb_load_bytes_relative(const void *skb, u32 offset, void *to, u32 len, u32 start_header) * Description diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 22c8ae94e4c1..2823dcefae10 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -166,7 +166,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, } static struct perf_callchain_entry * -get_callchain_entry_for_task(struct task_struct *task, u32 init_nr) +get_callchain_entry_for_task(struct task_struct *task, u32 max_depth) { #ifdef CONFIG_STACKTRACE struct perf_callchain_entry *entry; @@ -177,9 +177,8 @@ get_callchain_entry_for_task(struct task_struct *task, u32 init_nr) if (!entry) return NULL; - entry->nr = init_nr + - stack_trace_save_tsk(task, (unsigned long *)(entry->ip + init_nr), - sysctl_perf_event_max_stack - init_nr, 0); + entry->nr = stack_trace_save_tsk(task, (unsigned long *)entry->ip, + max_depth, 0); /* stack_trace_save_tsk() works on unsigned long array, while * perf_callchain_entry uses u64 array. For 32-bit systems, it is @@ -191,7 +190,7 @@ get_callchain_entry_for_task(struct task_struct *task, u32 init_nr) int i; /* copy data from the end to avoid using extra buffer */ - for (i = entry->nr - 1; i >= (int)init_nr; i--) + for (i = entry->nr - 1; i >= 0; i--) to[i] = (u64)(from[i]); } @@ -208,27 +207,19 @@ static long __bpf_get_stackid(struct bpf_map *map, { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *new_bucket, *old_bucket; - u32 max_depth = map->value_size / stack_map_data_size(map); - /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ - u32 init_nr = sysctl_perf_event_max_stack - max_depth; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; u32 hash, id, trace_nr, trace_len; bool user = flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches; - /* get_perf_callchain() guarantees that trace->nr >= init_nr - * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth - */ - trace_nr = trace->nr - init_nr; - - if (trace_nr <= skip) + if (trace->nr <= skip) /* skipping more than usable stack trace */ return -EFAULT; - trace_nr -= skip; + trace_nr = trace->nr - skip; trace_len = trace_nr * sizeof(u64); - ips = trace->ip + skip + init_nr; + ips = trace->ip + skip; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); id = hash & (smap->n_buckets - 1); bucket = READ_ONCE(smap->buckets[id]); @@ -285,8 +276,7 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, u64, flags) { u32 max_depth = map->value_size / stack_map_data_size(map); - /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ - u32 init_nr = sysctl_perf_event_max_stack - max_depth; + u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; @@ -295,8 +285,12 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; - trace = get_perf_callchain(regs, init_nr, kernel, user, - sysctl_perf_event_max_stack, false, false); + max_depth += skip; + if (max_depth > sysctl_perf_event_max_stack) + max_depth = sysctl_perf_event_max_stack; + + trace = get_perf_callchain(regs, 0, kernel, user, max_depth, + false, false); if (unlikely(!trace)) /* couldn't fetch the stack trace */ @@ -387,7 +381,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags) { - u32 init_nr, trace_nr, copy_len, elem_size, num_elem; + u32 trace_nr, copy_len, elem_size, num_elem, max_depth; bool user_build_id = flags & BPF_F_USER_BUILD_ID; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; @@ -412,30 +406,28 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, goto err_fault; num_elem = size / elem_size; - if (sysctl_perf_event_max_stack < num_elem) - init_nr = 0; - else - init_nr = sysctl_perf_event_max_stack - num_elem; + max_depth = num_elem + skip; + if (sysctl_perf_event_max_stack < max_depth) + max_depth = sysctl_perf_event_max_stack; if (trace_in) trace = trace_in; else if (kernel && task) - trace = get_callchain_entry_for_task(task, init_nr); + trace = get_callchain_entry_for_task(task, max_depth); else - trace = get_perf_callchain(regs, init_nr, kernel, user, - sysctl_perf_event_max_stack, + trace = get_perf_callchain(regs, 0, kernel, user, max_depth, false, false); if (unlikely(!trace)) goto err_fault; - trace_nr = trace->nr - init_nr; - if (trace_nr < skip) + if (trace->nr < skip) goto err_fault; - trace_nr -= skip; + trace_nr = trace->nr - skip; trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; copy_len = trace_nr * elem_size; - ips = trace->ip + skip + init_nr; + + ips = trace->ip + skip; if (user && user_build_id) stack_map_get_build_id_offset(buf, ips, trace_nr, user); else From patchwork Thu Mar 10 08:22:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 12776023 X-Patchwork-Delegate: bpf@iogearbox.net 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 C4967C4332F for ; Thu, 10 Mar 2022 08:22:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240278AbiCJIXM (ORCPT ); Thu, 10 Mar 2022 03:23:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234558AbiCJIXK (ORCPT ); Thu, 10 Mar 2022 03:23:10 -0500 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C15D1301B6; Thu, 10 Mar 2022 00:22:10 -0800 (PST) Received: by mail-pj1-x102c.google.com with SMTP id mm23-20020a17090b359700b001bfceefd8c6so1339992pjb.3; Thu, 10 Mar 2022 00:22:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=z/Mr8oh0sWKEm17KedkzMdcKpYvzoba3uTd2uHZZr9s=; b=X5ihtfVuum0YUKHMU2jEqc/tEzjv6a/y4+REtlgaXQECTGRJCtu/aJJcsq4m7/KfJK UMf4hBdUYJGwVdbYQU94a57SU+/YGmMW5CpdGa+K+enoInnOnlkuQh3oKmJpphJLPZIl g6wHG7Gb7E38d32RU4uxaz0ZXrnkuXDBBwUqkvhJdDUvd92wYPEmD1j8chbQ4sBo78xS +uy4b2cX5ouWwTKYhmfgqn6lWt88VxBQcyZ5pzEofdgRvdjJx0R5iv4xvk6HweHwxP8R L/mhBMQcw/f/ODTz0BevBtf7MG6muzgCjI3QRjpWzHLkYgayzOmhnQDnxJRKbAmQYIn7 wF2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=z/Mr8oh0sWKEm17KedkzMdcKpYvzoba3uTd2uHZZr9s=; b=Jr5vYbi+27vFnlf0Hpg+G1x5Y3PgAUo5gsbVD7pSdjGH12XqjjioGH1YnWJgcyMtZG f7WkA1qnv80bxblPv9R7E7Khe+q+ZLpnhRBBlJfwk72exXS91rbLUDnsvHIznrmQWELF QFQRw9kL9jhhndkrXV/tt5gPon71dfv/xQb/0n1N8Wxz2kIX23H49jbg5Oow/bLSnAcM DYp33yAbnxC3sqFkRfFsGMl3DEPJGQB8uBiTMGXhZaVF6JbCVj3EZLQcO9iwmc9WWHbq 3E2vQ8Y6t5y4NyhSrxwFqMqtfTRcbhsU/GMbymhwLjQbMxjN39z7fGEsVZOM98OHl7jT NQwg== X-Gm-Message-State: AOAM532MnYzqx2AjoVEqfgbDvpEBX8sx1kmmqiyV/ZtWTiCjLWoci8r0 Vo0x2YDwxZwThhAvfh5dNBzasvU1QRs= X-Google-Smtp-Source: ABdhPJxaKvATvJcKM/p3sRrZdAYUBZaW3EkkpE4vAwzzsPiNpXHpRAotjVf4CnOg/RpQyF5KKuyVMg== X-Received: by 2002:a17:90b:2092:b0:1be:e373:2ed9 with SMTP id hb18-20020a17090b209200b001bee3732ed9mr3773083pjb.128.1646900529744; Thu, 10 Mar 2022 00:22:09 -0800 (PST) Received: from balhae.hsd1.ca.comcast.net ([2601:647:4800:3540:e7f1:5749:9be:64e1]) by smtp.gmail.com with ESMTPSA id a12-20020a056a000c8c00b004e1a76f0a8asm5903008pfv.51.2022.03.10.00.22.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Mar 2022 00:22:09 -0800 (PST) Sender: Namhyung Kim From: Namhyung Kim To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org, LKML , Arnaldo Carvalho de Melo , Peter Zijlstra , Eugene Loh , Hao Luo Subject: [PATCH 2/2] bpf/selftests: Test skipping stacktrace Date: Thu, 10 Mar 2022 00:22:02 -0800 Message-Id: <20220310082202.1229345-2-namhyung@kernel.org> X-Mailer: git-send-email 2.35.1.723.g4982287a31-goog In-Reply-To: <20220310082202.1229345-1-namhyung@kernel.org> References: <20220310082202.1229345-1-namhyung@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Add a test case for stacktrace with skip > 0 using a small sized buffer. It didn't support skipping entries greater than or equal to the size of buffer and filled the skipped part with 0. Signed-off-by: Namhyung Kim --- .../bpf/prog_tests/stacktrace_map_skip.c | 72 ++++++++++++++++ .../selftests/bpf/progs/stacktrace_map_skip.c | 82 +++++++++++++++++++ 2 files changed, 154 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c create mode 100644 tools/testing/selftests/bpf/progs/stacktrace_map_skip.c diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c new file mode 100644 index 000000000000..bcb244aa3c78 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include "stacktrace_map_skip.skel.h" + +#define TEST_STACK_DEPTH 2 + +void test_stacktrace_map_skip(void) +{ + struct stacktrace_map_skip *skel; + int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd; + int err, stack_trace_len; + __u32 key, val, duration = 0; + + skel = stacktrace_map_skip__open_and_load(); + if (CHECK(!skel, "skel_open_and_load", "skeleton open failed\n")) + return; + + /* find map fds */ + control_map_fd = bpf_map__fd(skel->maps.control_map); + if (CHECK_FAIL(control_map_fd < 0)) + goto out; + + stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap); + if (CHECK_FAIL(stackid_hmap_fd < 0)) + goto out; + + stackmap_fd = bpf_map__fd(skel->maps.stackmap); + if (CHECK_FAIL(stackmap_fd < 0)) + goto out; + + stack_amap_fd = bpf_map__fd(skel->maps.stack_amap); + if (CHECK_FAIL(stack_amap_fd < 0)) + goto out; + + err = stacktrace_map_skip__attach(skel); + if (CHECK(err, "skel_attach", "skeleton attach failed\n")) + goto out; + + /* give some time for bpf program run */ + sleep(1); + + /* disable stack trace collection */ + key = 0; + val = 1; + bpf_map_update_elem(control_map_fd, &key, &val, 0); + + /* for every element in stackid_hmap, we can find a corresponding one + * in stackmap, and vise versa. + */ + err = compare_map_keys(stackid_hmap_fd, stackmap_fd); + if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap", + "err %d errno %d\n", err, errno)) + goto out; + + err = compare_map_keys(stackmap_fd, stackid_hmap_fd); + if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap", + "err %d errno %d\n", err, errno)) + goto out; + + stack_trace_len = TEST_STACK_DEPTH * sizeof(__u64); + err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len); + if (CHECK(err, "compare_stack_ips stackmap vs. stack_amap", + "err %d errno %d\n", err, errno)) + goto out; + + if (CHECK(skel->bss->failed, "check skip", + "failed to skip some depth: %d", skel->bss->failed)) + goto out; + +out: + stacktrace_map_skip__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c b/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c new file mode 100644 index 000000000000..323248b17ae4 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#define TEST_STACK_DEPTH 2 + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u32); +} control_map SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 16384); + __type(key, __u32); + __type(value, __u32); +} stackid_hmap SEC(".maps"); + +typedef __u64 stack_trace_t[TEST_STACK_DEPTH]; + +struct { + __uint(type, BPF_MAP_TYPE_STACK_TRACE); + __uint(max_entries, 16384); + __type(key, __u32); + __type(value, stack_trace_t); +} stackmap SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 16384); + __type(key, __u32); + __type(value, stack_trace_t); +} stack_amap SEC(".maps"); + +/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ +struct sched_switch_args { + unsigned long long pad; + char prev_comm[TASK_COMM_LEN]; + int prev_pid; + int prev_prio; + long long prev_state; + char next_comm[TASK_COMM_LEN]; + int next_pid; + int next_prio; +}; + +int failed = 0; + +SEC("tracepoint/sched/sched_switch") +int oncpu(struct sched_switch_args *ctx) +{ + __u32 max_len = TEST_STACK_DEPTH * sizeof(__u64); + __u32 key = 0, val = 0, *value_p; + __u64 *stack_p; + + value_p = bpf_map_lookup_elem(&control_map, &key); + if (value_p && *value_p) + return 0; /* skip if non-zero *value_p */ + + /* it should allow skipping whole buffer size entries */ + key = bpf_get_stackid(ctx, &stackmap, TEST_STACK_DEPTH); + if ((int)key >= 0) { + /* The size of stackmap and stack_amap should be the same */ + bpf_map_update_elem(&stackid_hmap, &key, &val, 0); + stack_p = bpf_map_lookup_elem(&stack_amap, &key); + if (stack_p) { + bpf_get_stack(ctx, stack_p, max_len, TEST_STACK_DEPTH); + /* it wrongly skipped all the entries and filled zero */ + if (stack_p[0] == 0) + failed = 1; + } + } else if ((int)key == -14/*EFAULT*/) { + /* old kernel doesn't support skipping that many entries */ + failed = 2; + } + + return 0; +} + +char _license[] SEC("license") = "GPL";