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@xxxxxx>
---
.../testing/selftests/bpf/bpf_experimental.h | 8 +++
.../testing/selftests/bpf/prog_tests/iters.c | 59 +++++++++++++++++++
.../selftests/bpf/progs/iters_task_vma.c | 46 +++++++++++++++
3 files changed, 113 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/iters_task_vma.c
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 9aa29564bd74..2c8cb3f61529 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -159,6 +159,14 @@ extern void *bpf_percpu_obj_new_impl(__u64 local_type_id, void *meta) __ksym;
*/
extern void bpf_percpu_obj_drop_impl(void *kptr, void *meta) __ksym;
+struct bpf_iter_task_vma;
+
+extern int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it,
+ struct task_struct *task,
+ unsigned long addr) __ksym;
+extern struct vm_area_struct *bpf_iter_task_vma_next(struct bpf_iter_task_vma *it) __ksym;
+extern void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it) __ksym;
+
/* Convenience macro to wrap over bpf_obj_drop_impl */
#define bpf_percpu_obj_drop(kptr) bpf_percpu_obj_drop_impl(kptr, NULL)
diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
index 10804ae5ae97..c837e6bbf38b 100644
--- a/tools/testing/selftests/bpf/prog_tests/iters.c
+++ b/tools/testing/selftests/bpf/prog_tests/iters.c
@@ -8,6 +8,7 @@
#include "iters_looping.skel.h"
#include "iters_num.skel.h"
#include "iters_testmod_seq.skel.h"
+#include "iters_task_vma.skel.h"
static void subtest_num_iters(void)
{
@@ -90,6 +91,62 @@ static void subtest_testmod_seq_iters(void)
iters_testmod_seq__destroy(skel);
}
+static void subtest_task_vma_iters(void)
+{
+ unsigned long start, end, bpf_iter_start, bpf_iter_end;
+ struct iters_task_vma *skel;
+ char rest_of_line[1000];
+ unsigned int seen;
+ int err;
+ FILE *f;
+
+ skel = iters_task_vma__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+ return;
+
+ skel->bss->target_pid = getpid();
+
+ err = iters_task_vma__attach(skel);
+ if (!ASSERT_OK(err, "skel_attach"))
+ goto cleanup;
+
+ getpgid(skel->bss->target_pid);
+ iters_task_vma__detach(skel);
+
+ if (!ASSERT_GT(skel->bss->vmas_seen, 0, "vmas_seen_gt_zero"))
+ goto cleanup;
+
+ f = fopen("/proc/self/maps", "r");
+ if (!ASSERT_OK_PTR(f, "proc_maps_fopen"))
+ goto cleanup;
+
+ seen = 0;
+ while (fscanf(f, "%lx-%lx %[^\n]\n", &start, &end, rest_of_line) == 3) {
+ /* [vsyscall] vma isn't _really_ part of task->mm vmas.
+ * /proc/PID/maps returns it when out of vmas - see get_gate_vma
+ * calls in fs/proc/task_mmu.c
+ */
+ if (strstr(rest_of_line, "[vsyscall]"))
+ continue;
+
+ bpf_iter_start = skel->bss->vm_ranges[seen].vm_start;
+ bpf_iter_end = skel->bss->vm_ranges[seen].vm_end;
+
+ ASSERT_EQ(bpf_iter_start, start, "vma->vm_start match");
+ ASSERT_EQ(bpf_iter_end, end, "vma->vm_end match");
+ seen++;
+ }
+
+ if (!ASSERT_EQ(skel->bss->vmas_seen, seen, "vmas_seen_eq"))
+ goto cleanup;
+
+cleanup:
+ if (f)
+ fclose(f);
+ iters_task_vma__destroy(skel);
+}
+
void test_iters(void)
{
RUN_TESTS(iters_state_safety);
@@ -103,4 +160,6 @@ void test_iters(void)
subtest_num_iters();
if (test__start_subtest("testmod_seq"))
subtest_testmod_seq_iters();
+ if (test__start_subtest("task_vma"))
+ subtest_task_vma_iters();
}
diff --git a/tools/testing/selftests/bpf/progs/iters_task_vma.c b/tools/testing/selftests/bpf/progs/iters_task_vma.c
new file mode 100644
index 000000000000..e3759e425420
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_task_vma.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <limits.h>
+#include <linux/errno.h>
+#include "vmlinux.h"
+#include "bpf_experimental.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+pid_t target_pid = 0;
+unsigned int vmas_seen = 0;
+
+struct {
+ __u64 vm_start;
+ __u64 vm_end;
+} vm_ranges[1000];
+
+SEC("raw_tp/sys_enter")
+int iter_task_vma_for_each(const void *ctx)
+{
+ struct task_struct *task = bpf_get_current_task_btf();
+ struct vm_area_struct *vma;
+ unsigned int seen = 0;
+
+ if (task->pid != target_pid)
+ return 0;
+
+ if (vmas_seen)
+ return 0;
+
+ bpf_for_each(task_vma, vma, task, 0) {
+ if (seen >= 1000)
+ break;
+
+ vm_ranges[seen].vm_start = vma->vm_start;
+ vm_ranges[seen].vm_end = vma->vm_end;
+ seen++;
+ }
+
+ if (!vmas_seen)
+ vmas_seen = seen;
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.34.1
