Commit 77fc0330 authored by Kenta Tada's avatar Kenta Tada Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add a test to confirm PT_REGS_PARM4_SYSCALL 



Add a selftest to verify the behavior of PT_REGS_xxx
and the CORE variant.

Signed-off-by: default avatarKenta Tada <Kenta.Tada@sony.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220124141622.4378-4-Kenta.Tada@sony.com
parent d084df3b

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright 2022 Sony Group Corporation */

#include <sys/prctl.h>

#include <test_progs.h>

#include "bpf_syscall_macro.skel.h"



void test_bpf_syscall_macro(void)

{

	struct bpf_syscall_macro *skel = NULL;

	int err;

	int exp_arg1 = 1001;

	unsigned long exp_arg2 = 12;

	unsigned long exp_arg3 = 13;

	unsigned long exp_arg4 = 14;

	unsigned long exp_arg5 = 15;



	/* check whether it can open program */

	skel = bpf_syscall_macro__open();

	if (!ASSERT_OK_PTR(skel, "bpf_syscall_macro__open"))

		return;



	skel->rodata->filter_pid = getpid();



	/* check whether it can load program */

	err = bpf_syscall_macro__load(skel);

	if (!ASSERT_OK(err, "bpf_syscall_macro__load"))

		goto cleanup;



	/* check whether it can attach kprobe */

	err = bpf_syscall_macro__attach(skel);

	if (!ASSERT_OK(err, "bpf_syscall_macro__attach"))

		goto cleanup;



	/* check whether args of syscall are copied correctly */

	prctl(exp_arg1, exp_arg2, exp_arg3, exp_arg4, exp_arg5);

	ASSERT_EQ(skel->bss->arg1, exp_arg1, "syscall_arg1");

	ASSERT_EQ(skel->bss->arg2, exp_arg2, "syscall_arg2");

	ASSERT_EQ(skel->bss->arg3, exp_arg3, "syscall_arg3");

	/* it cannot copy arg4 when uses PT_REGS_PARM4 on x86_64 */

#ifdef __x86_64__

	ASSERT_NEQ(skel->bss->arg4_cx, exp_arg4, "syscall_arg4_from_cx");

#else

	ASSERT_EQ(skel->bss->arg4_cx, exp_arg4, "syscall_arg4_from_cx");

#endif

	ASSERT_EQ(skel->bss->arg4, exp_arg4, "syscall_arg4");

	ASSERT_EQ(skel->bss->arg5, exp_arg5, "syscall_arg5");



	/* check whether args of syscall are copied correctly for CORE variants */

	ASSERT_EQ(skel->bss->arg1_core, exp_arg1, "syscall_arg1_core_variant");

	ASSERT_EQ(skel->bss->arg2_core, exp_arg2, "syscall_arg2_core_variant");

	ASSERT_EQ(skel->bss->arg3_core, exp_arg3, "syscall_arg3_core_variant");

	/* it cannot copy arg4 when uses PT_REGS_PARM4_CORE on x86_64 */

#ifdef __x86_64__

	ASSERT_NEQ(skel->bss->arg4_core_cx, exp_arg4, "syscall_arg4_from_cx_core_variant");

#else

	ASSERT_EQ(skel->bss->arg4_core_cx, exp_arg4, "syscall_arg4_from_cx_core_variant");

#endif

	ASSERT_EQ(skel->bss->arg4_core, exp_arg4, "syscall_arg4_core_variant");

	ASSERT_EQ(skel->bss->arg5_core, exp_arg5, "syscall_arg5_core_variant");



cleanup:

	bpf_syscall_macro__destroy(skel);

}

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright 2022 Sony Group Corporation */

#include <vmlinux.h>



#include <bpf/bpf_core_read.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include "bpf_misc.h"



int arg1 = 0;

unsigned long arg2 = 0;

unsigned long arg3 = 0;

unsigned long arg4_cx = 0;

unsigned long arg4 = 0;

unsigned long arg5 = 0;



int arg1_core = 0;

unsigned long arg2_core = 0;

unsigned long arg3_core = 0;

unsigned long arg4_core_cx = 0;

unsigned long arg4_core = 0;

unsigned long arg5_core = 0;



const volatile pid_t filter_pid = 0;



SEC("kprobe/" SYS_PREFIX "sys_prctl")

int BPF_KPROBE(handle_sys_prctl)

{

	struct pt_regs *real_regs;

	pid_t pid = bpf_get_current_pid_tgid() >> 32;



	if (pid != filter_pid)

		return 0;



	real_regs = (struct pt_regs *)PT_REGS_PARM1(ctx);



	/* test for PT_REGS_PARM */

	bpf_probe_read_kernel(&arg1, sizeof(arg1), &PT_REGS_PARM1_SYSCALL(real_regs));

	bpf_probe_read_kernel(&arg2, sizeof(arg2), &PT_REGS_PARM2_SYSCALL(real_regs));

	bpf_probe_read_kernel(&arg3, sizeof(arg3), &PT_REGS_PARM3_SYSCALL(real_regs));

	bpf_probe_read_kernel(&arg4_cx, sizeof(arg4_cx), &PT_REGS_PARM4(real_regs));

	bpf_probe_read_kernel(&arg4, sizeof(arg4), &PT_REGS_PARM4_SYSCALL(real_regs));

	bpf_probe_read_kernel(&arg5, sizeof(arg5), &PT_REGS_PARM5_SYSCALL(real_regs));



	/* test for the CORE variant of PT_REGS_PARM */

	arg1_core = PT_REGS_PARM1_CORE_SYSCALL(real_regs);

	arg2_core = PT_REGS_PARM2_CORE_SYSCALL(real_regs);

	arg3_core = PT_REGS_PARM3_CORE_SYSCALL(real_regs);

	arg4_core_cx = PT_REGS_PARM4_CORE(real_regs);

	arg4_core = PT_REGS_PARM4_CORE_SYSCALL(real_regs);

	arg5_core = PT_REGS_PARM5_CORE_SYSCALL(real_regs);



	return 0;

}



char _license[] SEC("license") = "GPL";