Commit 8c2e043d authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

selftests/bpf: check if bpf_fastcall is recognized for kfuncs 



Use kfunc_bpf_cast_to_kern_ctx() and kfunc_bpf_rdonly_cast() to verify
that bpf_fastcall pattern is recognized for kfunc calls.

Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240822084112.3257995-7-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent f406026f

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

+55 −0
Original line number Diff line number Diff line
@@ -2,8 +2,11 @@ 


#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_core_read.h>

#include "../../../include/linux/filter.h"

#include "bpf_misc.h"

#include <stdbool.h>

#include "bpf_kfuncs.h"



SEC("raw_tp")

__arch_x86_64
@@ -842,4 +845,56 @@ __naked int bpf_fastcall_max_stack_fail(void) 
	);

}



SEC("cgroup/getsockname_unix")

__xlated("0: r2 = 1")

/* bpf_cast_to_kern_ctx is replaced by a single assignment */

__xlated("1: r0 = r1")

__xlated("2: r0 = r2")

__xlated("3: exit")

__success

__naked void kfunc_bpf_cast_to_kern_ctx(void)

{

	asm volatile (

	"r2 = 1;"

	"*(u64 *)(r10 - 32) = r2;"

	"call %[bpf_cast_to_kern_ctx];"

	"r2 = *(u64 *)(r10 - 32);"

	"r0 = r2;"

	"exit;"

	:

	: __imm(bpf_cast_to_kern_ctx)

	: __clobber_all);

}



SEC("raw_tp")

__xlated("3: r3 = 1")

/* bpf_rdonly_cast is replaced by a single assignment */

__xlated("4: r0 = r1")

__xlated("5: r0 = r3")

void kfunc_bpf_rdonly_cast(void)

{

	asm volatile (

	"r2 = %[btf_id];"

	"r3 = 1;"

	"*(u64 *)(r10 - 32) = r3;"

	"call %[bpf_rdonly_cast];"

	"r3 = *(u64 *)(r10 - 32);"

	"r0 = r3;"

	:

	: __imm(bpf_rdonly_cast),

	 [btf_id]"r"(bpf_core_type_id_kernel(union bpf_attr))

	: __clobber_common);

}



/* BTF FUNC records are not generated for kfuncs referenced

 * from inline assembly. These records are necessary for

 * libbpf to link the program. The function below is a hack

 * to ensure that BTF FUNC records are generated.

 */

void kfunc_root(void)

{

	bpf_cast_to_kern_ctx(0);

	bpf_rdonly_cast(0, 0);

}



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