bpf: selftests: Add bpf_task_pt_regs() selftest

This test retrieves the uprobe's pt_regs in two different ways and
compares the contents in an arch-agnostic way.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/5581eb8800f6625ec8813fe21e9dce1fbdef4937.1629772842.git.dxu@dxuuu.xyz

diff --git a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
new file mode 100644 (file)
index 0000000..53f0e0f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <test_progs.h>
+#include <linux/ptrace.h>
+#include "test_task_pt_regs.skel.h"
+
+void test_task_pt_regs(void)
+{
+       struct test_task_pt_regs *skel;
+       struct bpf_link *uprobe_link;
+       size_t uprobe_offset;
+       ssize_t base_addr;
+       bool match;
+
+       base_addr = get_base_addr();
+       if (!ASSERT_GT(base_addr, 0, "get_base_addr"))
+               return;
+       uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
+
+       skel = test_task_pt_regs__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "skel_open"))
+               return;
+       if (!ASSERT_OK_PTR(skel->bss, "check_bss"))
+               goto cleanup;
+
+       uprobe_link = bpf_program__attach_uprobe(skel->progs.handle_uprobe,
+                                                false /* retprobe */,
+                                                0 /* self pid */,
+                                                "/proc/self/exe",
+                                                uprobe_offset);
+       if (!ASSERT_OK_PTR(uprobe_link, "attach_uprobe"))
+               goto cleanup;
+       skel->links.handle_uprobe = uprobe_link;
+
+       /* trigger & validate uprobe */
+       get_base_addr();
+
+       if (!ASSERT_EQ(skel->bss->uprobe_res, 1, "check_uprobe_res"))
+               goto cleanup;
+
+       match = !memcmp(&skel->bss->current_regs, &skel->bss->ctx_regs,
+                       sizeof(skel->bss->current_regs));
+       ASSERT_TRUE(match, "check_regs_match");
+
+cleanup:
+       test_task_pt_regs__destroy(skel);
+}

diff --git a/tools/testing/selftests/bpf/progs/test_task_pt_regs.c b/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
new file mode 100644 (file)
index 0000000..6c059f1
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/ptrace.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct pt_regs current_regs = {};
+struct pt_regs ctx_regs = {};
+int uprobe_res = 0;
+
+SEC("uprobe/trigger_func")
+int handle_uprobe(struct pt_regs *ctx)
+{
+       struct task_struct *current;
+       struct pt_regs *regs;
+
+       current = bpf_get_current_task_btf();
+       regs = (struct pt_regs *) bpf_task_pt_regs(current);
+       __builtin_memcpy(&current_regs, regs, sizeof(*regs));
+       __builtin_memcpy(&ctx_regs, ctx, sizeof(*ctx));
+
+       /* Prove that uprobe was run */
+       uprobe_res = 1;
+
+       return 0;
+}
+
+char _license[] SEC("license") = "GPL";