Commit 576d47bb authored by Daniel Xu's avatar Daniel Xu Committed by Alexei Starovoitov
Browse files

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: default avatarDaniel Xu <dxu@dxuuu.xyz>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/5581eb8800f6625ec8813fe21e9dce1fbdef4937.1629772842.git.dxu@dxuuu.xyz
parent dd6e10fb

tools/testing/selftests/bpf/prog_tests/task_pt_regs.c

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// 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);

}

tools/testing/selftests/bpf/progs/test_task_pt_regs.c

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// 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";