From: Xu Kuohai <xukuohai@huawei.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: <bpf@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Zi Shen Lim <zlim.lnx@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>, <x86@kernel.org>,
<hpa@zytor.com>, Shuah Khan <shuah@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Ard Biesheuvel <ardb@kernel.org>,
Daniel Kiss <daniel.kiss@arm.com>,
Steven Price <steven.price@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Marc Zyngier <maz@kernel.org>,
Peter Collingbourne <pcc@google.com>,
Mark Brown <broonie@kernel.org>, Delyan Kratunov <delyank@fb.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>
Subject: Re: [PATCH bpf-next v4 3/6] bpf: Move is_valid_bpf_tramp_flags() to the public trampoline code
Date: Wed, 18 May 2022 11:35:43 +0800 [thread overview]
Message-ID: <c6dfe9bc-07ac-62a7-0a34-12fecf0dfdaa@huawei.com> (raw)
In-Reply-To: <20220517155349.4jk5oymnjvrasw2p@MacBook-Pro.local>
On 5/17/2022 11:53 PM, Alexei Starovoitov wrote:
> On Tue, May 17, 2022 at 03:18:35AM -0400, Xu Kuohai wrote:
>>
>> +static bool is_valid_bpf_tramp_flags(unsigned int flags)
>> +{
>> + if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
>> + (flags & BPF_TRAMP_F_SKIP_FRAME))
>> + return false;
>> +
>> + /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
>> + * and it must be used alone.
>> + */
>> + if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) &&
>> + (flags & ~BPF_TRAMP_F_RET_FENTRY_RET))
>> + return false;
>> +
>> + return true;
>> +}
>> +
>> +int bpf_prepare_trampoline(struct bpf_tramp_image *tr, void *image,
>> + void *image_end, const struct btf_func_model *m,
>> + u32 flags, struct bpf_tramp_links *tlinks,
>> + void *orig_call)
>> +{
>> + if (!is_valid_bpf_tramp_flags(flags))
>> + return -EINVAL;
>> +
>> + return arch_prepare_bpf_trampoline(tr, image, image_end, m, flags,
>> + tlinks, orig_call);
>> +}
>
> It's an overkill to introduce a new helper function just to validate
> flags that almost compile time constants.
> The flags are not user supplied.
> Please move /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops ... */
> comment to bpf_struct_ops.c right before it calls arch_prepare_bpf_trampoline()
> And add a comment to trampoline.c saying that BPF_TRAMP_F_RESTORE_REGS
> and BPF_TRAMP_F_SKIP_FRAME should not be set together.
> We could add a warn_on there or in arch code, but feels like overkill.
> .
OK, will fix in next version.
next prev parent reply other threads:[~2022-05-18 3:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-17 7:18 [PATCH bpf-next v4 0/6] bpf trampoline for arm64 Xu Kuohai
2022-05-17 7:18 ` [PATCH bpf-next v4 1/6] arm64: ftrace: Add ftrace direct call support Xu Kuohai
2022-05-17 7:18 ` [PATCH bpf-next v4 2/6] ftrace: Fix deadloop caused by direct call in ftrace selftest Xu Kuohai
2022-05-18 19:57 ` Steven Rostedt
2022-05-17 7:18 ` [PATCH bpf-next v4 3/6] bpf: Move is_valid_bpf_tramp_flags() to the public trampoline code Xu Kuohai
2022-05-17 15:53 ` Alexei Starovoitov
2022-05-18 3:35 ` Xu Kuohai [this message]
2022-05-17 7:18 ` [PATCH bpf-next v4 4/6] bpf, arm64: Impelment bpf_arch_text_poke() for arm64 Xu Kuohai
2022-05-17 7:18 ` [PATCH bpf-next v4 5/6] bpf, arm64: bpf trampoline " Xu Kuohai
2022-05-17 7:18 ` [PATCH bpf-next v4 6/6] selftests/bpf: Fix trivial typo in fentry_fexit.c Xu Kuohai
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