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1// SPDX-License-Identifier: GPL-2.02/* Copyright (c) 2020 Facebook */3#include "bpf_iter.h"4#include <bpf/bpf_helpers.h>5 6char _license[] SEC("license") = "GPL";7 8#define MAX_STACK_TRACE_DEPTH 649unsigned long entries[MAX_STACK_TRACE_DEPTH] = {};10#define SIZE_OF_ULONG (sizeof(unsigned long))11 12SEC("iter/task")13int dump_task_stack(struct bpf_iter__task *ctx)14{15 struct seq_file *seq = ctx->meta->seq;16 struct task_struct *task = ctx->task;17 long i, retlen;18 19 if (task == (void *)0)20 return 0;21 22 retlen = bpf_get_task_stack(task, entries,23 MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);24 if (retlen < 0)25 return 0;26 27 BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,28 retlen / SIZE_OF_ULONG);29 for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {30 if (retlen > i * SIZE_OF_ULONG)31 BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);32 }33 BPF_SEQ_PRINTF(seq, "\n");34 35 return 0;36}37 38int num_user_stacks = 0;39 40SEC("iter/task")41int get_task_user_stacks(struct bpf_iter__task *ctx)42{43 struct seq_file *seq = ctx->meta->seq;44 struct task_struct *task = ctx->task;45 uint64_t buf_sz = 0;46 int64_t res;47 48 if (task == (void *)0)49 return 0;50 51 res = bpf_get_task_stack(task, entries,52 MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, BPF_F_USER_STACK);53 if (res <= 0)54 return 0;55 56 /* Only one task, the current one, should succeed */57 ++num_user_stacks;58 59 buf_sz += res;60 61 /* If the verifier doesn't refine bpf_get_task_stack res, and instead62 * assumes res is entirely unknown, this program will fail to load as63 * the verifier will believe that max buf_sz value allows reading64 * past the end of entries in bpf_seq_write call65 */66 bpf_seq_write(seq, &entries, buf_sz);67 return 0;68}69