Re: [PATCH bpf-next 5/5] selftests/bpf: use BPF_KSYSCALL and SEC("ksyscall") in selftests

[sdf@xxxxxxxxxx]

On 07/12, Andrii Nakryiko wrote:
> Convert few selftest that used plain SEC("kprobe") with arch-specific
> syscall wrapper prefix to ksyscall/kretsyscall and corresponding
> BPF_KSYSCALL macro. test_probe_user.c is especially benefiting from this
> simplification.

That looks super nice! I'm assuming the goal is probably
to get rid of that SYS_PREFIX everywhere eventually? And have a simple
test that exercises fentry/etc parsing?

> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
>   .../selftests/bpf/progs/bpf_syscall_macro.c   |  6 ++---
>   .../selftests/bpf/progs/test_attach_probe.c   | 15 +++++------
>   .../selftests/bpf/progs/test_probe_user.c     | 27 +++++--------------
>   3 files changed, 16 insertions(+), 32 deletions(-)

> diff --git a/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c  
> b/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
> index 05838ed9b89c..e1e11897e99b 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
> +++ b/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
> @@ -64,9 +64,9 @@ int BPF_KPROBE(handle_sys_prctl)
>   	return 0;
>   }

> -SEC("kprobe/" SYS_PREFIX "sys_prctl")
> -int BPF_KPROBE_SYSCALL(prctl_enter, int option, unsigned long arg2,
> -		       unsigned long arg3, unsigned long arg4, unsigned long arg5)
> +SEC("ksyscall/prctl")
> +int BPF_KSYSCALL(prctl_enter, int option, unsigned long arg2,
> +		 unsigned long arg3, unsigned long arg4, unsigned long arg5)
>   {
>   	pid_t pid = bpf_get_current_pid_tgid() >> 32;

> diff --git a/tools/testing/selftests/bpf/progs/test_attach_probe.c  
> b/tools/testing/selftests/bpf/progs/test_attach_probe.c
> index f1c88ad368ef..a1e45fec8938 100644
> --- a/tools/testing/selftests/bpf/progs/test_attach_probe.c
> +++ b/tools/testing/selftests/bpf/progs/test_attach_probe.c
> @@ -1,11 +1,10 @@
>   // SPDX-License-Identifier: GPL-2.0
>   // Copyright (c) 2017 Facebook

> -#include <linux/ptrace.h>
> -#include <linux/bpf.h>
> +#include "vmlinux.h"
>   #include <bpf/bpf_helpers.h>
>   #include <bpf/bpf_tracing.h>
> -#include <stdbool.h>
> +#include <bpf/bpf_core_read.h>
>   #include "bpf_misc.h"

>   int kprobe_res = 0;
> @@ -31,8 +30,8 @@ int handle_kprobe(struct pt_regs *ctx)
>   	return 0;
>   }

> -SEC("kprobe/" SYS_PREFIX "sys_nanosleep")
> -int BPF_KPROBE(handle_kprobe_auto)
> +SEC("ksyscall/nanosleep")
> +int BPF_KSYSCALL(handle_kprobe_auto, struct __kernel_timespec *req,  
> struct __kernel_timespec *rem)
>   {
>   	kprobe2_res = 11;
>   	return 0;
> @@ -56,11 +55,11 @@ int handle_kretprobe(struct pt_regs *ctx)
>   	return 0;
>   }

> -SEC("kretprobe/" SYS_PREFIX "sys_nanosleep")
> -int BPF_KRETPROBE(handle_kretprobe_auto)
> +SEC("kretsyscall/nanosleep")
> +int BPF_KRETPROBE(handle_kretprobe_auto, int ret)
>   {
>   	kretprobe2_res = 22;
> -	return 0;
> +	return ret;
>   }

>   SEC("uprobe")
> diff --git a/tools/testing/selftests/bpf/progs/test_probe_user.c  
> b/tools/testing/selftests/bpf/progs/test_probe_user.c
> index 702578a5e496..8e1495008e4d 100644
> --- a/tools/testing/selftests/bpf/progs/test_probe_user.c
> +++ b/tools/testing/selftests/bpf/progs/test_probe_user.c
> @@ -1,35 +1,20 @@
>   // SPDX-License-Identifier: GPL-2.0
> -
> -#include <linux/ptrace.h>
> -#include <linux/bpf.h>
> -
> -#include <netinet/in.h>
> -
> +#include "vmlinux.h"
>   #include <bpf/bpf_helpers.h>
>   #include <bpf/bpf_tracing.h>
> +#include <bpf/bpf_core_read.h>
>   #include "bpf_misc.h"

>   static struct sockaddr_in old;

> -SEC("kprobe/" SYS_PREFIX "sys_connect")
> -int BPF_KPROBE(handle_sys_connect)
> +SEC("ksyscall/connect")
> +int BPF_KSYSCALL(handle_sys_connect, int fd, struct sockaddr_in  
> *uservaddr, int addrlen)
>   {
> -#if SYSCALL_WRAPPER == 1
> -	struct pt_regs *real_regs;
> -#endif
>   	struct sockaddr_in new;
> -	void *ptr;
> -
> -#if SYSCALL_WRAPPER == 0
> -	ptr = (void *)PT_REGS_PARM2(ctx);
> -#else
> -	real_regs = (struct pt_regs *)PT_REGS_PARM1(ctx);
> -	bpf_probe_read_kernel(&ptr, sizeof(ptr), &PT_REGS_PARM2(real_regs));
> -#endif

> -	bpf_probe_read_user(&old, sizeof(old), ptr);
> +	bpf_probe_read_user(&old, sizeof(old), uservaddr);
>   	__builtin_memset(&new, 0xab, sizeof(new));
> -	bpf_probe_write_user(ptr, &new, sizeof(new));
> +	bpf_probe_write_user(uservaddr, &new, sizeof(new));

>   	return 0;
>   }
> --
> 2.30.2