Commit c48e51c8 authored by Kumar Kartikeya Dwivedi's avatar Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov
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bpf: selftests: Add selftests for module kfunc support 



This adds selftests that tests the success and failure path for modules
kfuncs (in presence of invalid kfunc calls) for both libbpf and
gen_loader. It also adds a prog_test kfunc_btf_id_list so that we can
add module BTF ID set from bpf_testmod.

This also introduces  a couple of test cases to verifier selftests for
validating whether we get an error or not depending on if invalid kfunc
call remains after elimination of unreachable instructions.

Signed-off-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-10-memxor@gmail.com
parent 18f4fccb

include/linux/btf.h

+1 −0
Original line number Diff line number Diff line
@@ -275,5 +275,6 @@ static inline bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, 
					 THIS_MODULE }



extern struct kfunc_btf_id_list bpf_tcp_ca_kfunc_list;

extern struct kfunc_btf_id_list prog_test_kfunc_list;



#endif

kernel/bpf/btf.c

+1 −0
Original line number Diff line number Diff line
@@ -6397,3 +6397,4 @@ bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, u32 kfunc_id, 
	EXPORT_SYMBOL_GPL(name)



DEFINE_KFUNC_BTF_ID_LIST(bpf_tcp_ca_kfunc_list);

DEFINE_KFUNC_BTF_ID_LIST(prog_test_kfunc_list);

net/bpf/test_run.c

+4 −1
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
/* Copyright (c) 2017 Facebook

 */

#include <linux/bpf.h>

#include <linux/btf.h>

#include <linux/btf_ids.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>
@@ -243,7 +244,9 @@ BTF_SET_END(test_sk_kfunc_ids) 


bool bpf_prog_test_check_kfunc_call(u32 kfunc_id, struct module *owner)

{

	return btf_id_set_contains(&test_sk_kfunc_ids, kfunc_id);

	if (btf_id_set_contains(&test_sk_kfunc_ids, kfunc_id))

		return true;

	return bpf_check_mod_kfunc_call(&prog_test_kfunc_list, kfunc_id, owner);

}



static void *bpf_test_init(const union bpf_attr *kattr, u32 size,

tools/testing/selftests/bpf/Makefile

+4 −3
Original line number Diff line number Diff line
@@ -315,8 +315,9 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ 
		linked_vars.skel.h linked_maps.skel.h



LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \

	test_ksyms_module.c test_ringbuf.c atomics.c trace_printk.c \

	trace_vprintk.c

	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c

# Generate both light skeleton and libbpf skeleton for these

LSKELS_EXTRA := test_ksyms_module.c

SKEL_BLACKLIST += $$(LSKELS)



test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o
@@ -346,7 +347,7 @@ TRUNNER_BPF_OBJS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.o, $$(TRUNNER_BPF_SRCS) 
TRUNNER_BPF_SKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.skel.h,	\

				 $$(filter-out $(SKEL_BLACKLIST) $(LINKED_BPF_SRCS),\

					       $$(TRUNNER_BPF_SRCS)))

TRUNNER_BPF_LSKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.lskel.h, $$(LSKELS))

TRUNNER_BPF_LSKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.lskel.h, $$(LSKELS) $$(LSKELS_EXTRA))

TRUNNER_BPF_SKELS_LINKED := $$(addprefix $$(TRUNNER_OUTPUT)/,$(LINKED_SKELS))

TEST_GEN_FILES += $$(TRUNNER_BPF_OBJS)

tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c

+22 −1
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2020 Facebook */

#include <linux/btf.h>

#include <linux/btf_ids.h>

#include <linux/error-injection.h>

#include <linux/init.h>

#include <linux/module.h>
@@ -13,6 +15,12 @@ 


DEFINE_PER_CPU(int, bpf_testmod_ksym_percpu) = 123;



noinline void

bpf_testmod_test_mod_kfunc(int i)

{

	*(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;

}



noinline int bpf_testmod_loop_test(int n)

{

	int i, sum = 0;
@@ -71,13 +79,26 @@ static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = { 
	.write = bpf_testmod_test_write,

};



BTF_SET_START(bpf_testmod_kfunc_ids)

BTF_ID(func, bpf_testmod_test_mod_kfunc)

BTF_SET_END(bpf_testmod_kfunc_ids)



static DEFINE_KFUNC_BTF_ID_SET(&bpf_testmod_kfunc_ids, bpf_testmod_kfunc_btf_set);



static int bpf_testmod_init(void)

{

	return sysfs_create_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);

	int ret;



	ret = sysfs_create_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);

	if (ret)

		return ret;

	register_kfunc_btf_id_set(&prog_test_kfunc_list, &bpf_testmod_kfunc_btf_set);

	return 0;

}



static void bpf_testmod_exit(void)

{

	unregister_kfunc_btf_id_set(&prog_test_kfunc_list, &bpf_testmod_kfunc_btf_set);

	return sysfs_remove_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);

}