c7568114bc
The new test is similar to other bpf_iter tests. It dumps all /proc/<pid>/stack to a seq_file. Here is some example output: pid: 2873 num_entries: 3 [<0>] worker_thread+0xc6/0x380 [<0>] kthread+0x135/0x150 [<0>] ret_from_fork+0x22/0x30 pid: 2874 num_entries: 9 [<0>] __bpf_get_stack+0x15e/0x250 [<0>] bpf_prog_22a400774977bb30_dump_task_stack+0x4a/0xb3c [<0>] bpf_iter_run_prog+0x81/0x170 [<0>] __task_seq_show+0x58/0x80 [<0>] bpf_seq_read+0x1c3/0x3b0 [<0>] vfs_read+0x9e/0x170 [<0>] ksys_read+0xa7/0xe0 [<0>] do_syscall_64+0x4c/0xa0 [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Note: bpf_iter test as-is doesn't print the contents of the seq_file. To see the example above, it is necessary to add printf() to do_dummy_read. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200630062846.664389-5-songliubraving@fb.com
37 lines
928 B
C
37 lines
928 B
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2020 Facebook */
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#include "bpf_iter.h"
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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char _license[] SEC("license") = "GPL";
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#define MAX_STACK_TRACE_DEPTH 64
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unsigned long entries[MAX_STACK_TRACE_DEPTH];
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#define SIZE_OF_ULONG (sizeof(unsigned long))
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SEC("iter/task")
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int dump_task_stack(struct bpf_iter__task *ctx)
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{
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struct seq_file *seq = ctx->meta->seq;
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struct task_struct *task = ctx->task;
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long i, retlen;
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if (task == (void *)0)
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return 0;
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retlen = bpf_get_task_stack(task, entries,
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MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);
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if (retlen < 0)
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return 0;
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BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,
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retlen / SIZE_OF_ULONG);
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for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {
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if (retlen > i * SIZE_OF_ULONG)
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BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);
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}
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BPF_SEQ_PRINTF(seq, "\n");
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return 0;
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}
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