Commit cada0bdc authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test epilogue patching when the main prog has multiple BPF_EXIT 



This patch tests the epilogue patching when the main prog has
multiple BPF_EXIT. The verifier should have patched the 2nd (and
later) BPF_EXIT with a BPF_JA that goes back to the earlier
patched epilogue instructions.

Acked-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240829210833.388152-10-martin.lau@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 42fdbbde

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

+2 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include "pro_epilogue.skel.h"

#include "epilogue_tailcall.skel.h"

#include "pro_epilogue_goto_start.skel.h"

#include "epilogue_exit.skel.h"



struct st_ops_args {

	__u64 a;
@@ -53,6 +54,7 @@ void test_pro_epilogue(void) 
{

	RUN_TESTS(pro_epilogue);

	RUN_TESTS(pro_epilogue_goto_start);

	RUN_TESTS(epilogue_exit);

	if (test__start_subtest("tailcall"))

		test_tailcall();

}

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

0 → 100644
+82 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */



#include <vmlinux.h>

#include <bpf/bpf_tracing.h>

#include "bpf_misc.h"

#include "../bpf_testmod/bpf_testmod.h"

#include "../bpf_testmod/bpf_testmod_kfunc.h"



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



__success

/* save __u64 *ctx to stack */

__xlated("0: *(u64 *)(r10 -8) = r1")

/* main prog */

__xlated("1: r1 = *(u64 *)(r1 +0)")

__xlated("2: r2 = *(u64 *)(r1 +0)")

__xlated("3: r3 = 0")

__xlated("4: r4 = 1")

__xlated("5: if r2 == 0x0 goto pc+10")

__xlated("6: r0 = 0")

__xlated("7: *(u64 *)(r1 +0) = r3")

/* epilogue */

__xlated("8: r1 = *(u64 *)(r10 -8)")

__xlated("9: r1 = *(u64 *)(r1 +0)")

__xlated("10: r6 = *(u64 *)(r1 +0)")

__xlated("11: r6 += 10000")

__xlated("12: *(u64 *)(r1 +0) = r6")

__xlated("13: r0 = r6")

__xlated("14: r0 *= 2")

__xlated("15: exit")

/* 2nd part of the main prog after the first exit */

__xlated("16: *(u64 *)(r1 +0) = r4")

__xlated("17: r0 = 1")

/* Clear the r1 to ensure it does not have

 * off-by-1 error and ensure it jumps back to the

 * beginning of epilogue which initializes

 * the r1 with the ctx ptr.

 */

__xlated("18: r1 = 0")

__xlated("19: gotol pc-12")

SEC("struct_ops/test_epilogue_exit")

__naked int test_epilogue_exit(void)

{

	asm volatile (

	"r1 = *(u64 *)(r1 +0);"

	"r2 = *(u64 *)(r1 +0);"

	"r3 = 0;"

	"r4 = 1;"

	"if r2 == 0 goto +3;"

	"r0 = 0;"

	"*(u64 *)(r1 + 0) = r3;"

	"exit;"

	"*(u64 *)(r1 + 0) = r4;"

	"r0 = 1;"

	"r1 = 0;"

	"exit;"

	::: __clobber_all);

}



SEC(".struct_ops.link")

struct bpf_testmod_st_ops epilogue_exit = {

	.test_epilogue = (void *)test_epilogue_exit,

};



SEC("syscall")

__retval(20000)

int syscall_epilogue_exit0(void *ctx)

{

	struct st_ops_args args = { .a = 1 };



	return bpf_kfunc_st_ops_test_epilogue(&args);

}



SEC("syscall")

__retval(20002)

int syscall_epilogue_exit1(void *ctx)

{

	struct st_ops_args args = {};



	return bpf_kfunc_st_ops_test_epilogue(&args);

}