selftests/bpf: Add tests for open-coded task_vma iter
The open-coded task_vma iter added earlier in this series allows for natural iteration over a task's vmas using existing open-coded iter infrastructure, specifically bpf_for_each. This patch adds a test demonstrating this pattern and validating correctness. The vma->vm_start and vma->vm_end addresses of the first 1000 vmas are recorded and compared to /proc/PID/maps output. As expected, both see the same vmas and addresses - with the exception of the [vsyscall] vma - which is explained in a comment in the prog_tests program. Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20231013204426.1074286-5-davemarchevsky@fb.com
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@ -159,6 +159,14 @@ extern void *bpf_percpu_obj_new_impl(__u64 local_type_id, void *meta) __ksym;
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*/
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extern void bpf_percpu_obj_drop_impl(void *kptr, void *meta) __ksym;
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struct bpf_iter_task_vma;
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extern int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it,
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struct task_struct *task,
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unsigned long addr) __ksym;
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extern struct vm_area_struct *bpf_iter_task_vma_next(struct bpf_iter_task_vma *it) __ksym;
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extern void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it) __ksym;
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/* Convenience macro to wrap over bpf_obj_drop_impl */
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#define bpf_percpu_obj_drop(kptr) bpf_percpu_obj_drop_impl(kptr, NULL)
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@ -8,6 +8,7 @@
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#include "iters_looping.skel.h"
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#include "iters_num.skel.h"
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#include "iters_testmod_seq.skel.h"
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#include "iters_task_vma.skel.h"
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static void subtest_num_iters(void)
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{
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@ -90,6 +91,61 @@ cleanup:
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iters_testmod_seq__destroy(skel);
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}
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static void subtest_task_vma_iters(void)
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{
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unsigned long start, end, bpf_iter_start, bpf_iter_end;
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struct iters_task_vma *skel;
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char rest_of_line[1000];
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unsigned int seen;
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FILE *f = NULL;
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int err;
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skel = iters_task_vma__open_and_load();
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if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
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return;
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skel->bss->target_pid = getpid();
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err = iters_task_vma__attach(skel);
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if (!ASSERT_OK(err, "skel_attach"))
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goto cleanup;
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getpgid(skel->bss->target_pid);
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iters_task_vma__detach(skel);
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if (!ASSERT_GT(skel->bss->vmas_seen, 0, "vmas_seen_gt_zero"))
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goto cleanup;
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f = fopen("/proc/self/maps", "r");
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if (!ASSERT_OK_PTR(f, "proc_maps_fopen"))
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goto cleanup;
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seen = 0;
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while (fscanf(f, "%lx-%lx %[^\n]\n", &start, &end, rest_of_line) == 3) {
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/* [vsyscall] vma isn't _really_ part of task->mm vmas.
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* /proc/PID/maps returns it when out of vmas - see get_gate_vma
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* calls in fs/proc/task_mmu.c
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*/
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if (strstr(rest_of_line, "[vsyscall]"))
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continue;
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bpf_iter_start = skel->bss->vm_ranges[seen].vm_start;
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bpf_iter_end = skel->bss->vm_ranges[seen].vm_end;
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ASSERT_EQ(bpf_iter_start, start, "vma->vm_start match");
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ASSERT_EQ(bpf_iter_end, end, "vma->vm_end match");
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seen++;
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}
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if (!ASSERT_EQ(skel->bss->vmas_seen, seen, "vmas_seen_eq"))
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goto cleanup;
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cleanup:
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if (f)
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fclose(f);
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iters_task_vma__destroy(skel);
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}
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void test_iters(void)
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{
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RUN_TESTS(iters_state_safety);
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@ -103,4 +159,6 @@ void test_iters(void)
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subtest_num_iters();
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if (test__start_subtest("testmod_seq"))
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subtest_testmod_seq_iters();
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if (test__start_subtest("task_vma"))
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subtest_task_vma_iters();
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}
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43
tools/testing/selftests/bpf/progs/iters_task_vma.c
Normal file
43
tools/testing/selftests/bpf/progs/iters_task_vma.c
Normal file
@ -0,0 +1,43 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
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#include "vmlinux.h"
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#include "bpf_experimental.h"
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#include <bpf/bpf_helpers.h>
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#include "bpf_misc.h"
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pid_t target_pid = 0;
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unsigned int vmas_seen = 0;
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struct {
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__u64 vm_start;
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__u64 vm_end;
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} vm_ranges[1000];
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SEC("raw_tp/sys_enter")
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int iter_task_vma_for_each(const void *ctx)
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{
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struct task_struct *task = bpf_get_current_task_btf();
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struct vm_area_struct *vma;
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unsigned int seen = 0;
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if (task->pid != target_pid)
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return 0;
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if (vmas_seen)
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return 0;
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bpf_for_each(task_vma, vma, task, 0) {
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if (seen >= 1000)
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break;
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vm_ranges[seen].vm_start = vma->vm_start;
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vm_ranges[seen].vm_end = vma->vm_end;
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seen++;
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}
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vmas_seen = seen;
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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