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selftests/bpf: check if bpf_fastcall is recognized for kfuncs

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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: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240822084112.3257995-7-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman 2024-08-22 01:41:12 -07:00 committed by Alexei Starovoitov
parent f406026fef
commit 8c2e043daa
1 changed files with 55 additions and 0 deletions
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55
tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
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@ -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";