From: Dave Hansen <dave.hansen@intel.com>
To: "Yu, Yu-cheng" <yu-cheng.yu@intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@kernel.org>,
Balbir Singh <bsingharora@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>
Subject: Re: [PATCH v18 24/25] x86/cet/shstk: Add arch_prctl functions for shadow stack
Date: Wed, 3 Feb 2021 14:11:40 -0800 [thread overview]
Message-ID: <a7ef2df2-815f-9994-11b7-026afe45094f@intel.com> (raw)
In-Reply-To: <6720b1a9-f785-dbbd-1f0e-8c9090be2069@intel.com>
On 2/3/21 1:54 PM, Yu, Yu-cheng wrote:
> On 1/29/2021 10:56 AM, Yu, Yu-cheng wrote:
>> On 1/29/2021 9:07 AM, Dave Hansen wrote:
>>> On 1/27/21 1:25 PM, Yu-cheng Yu wrote:
>>>> + if (!IS_ENABLED(CONFIG_X86_CET))
>>>> + return -EOPNOTSUPP;
>>>
>>> Let's ignore glibc for a moment. What error code *should* the kernel be
>>> returning here? errno(3) says:
>>>
>>> EOPNOTSUPP Operation not supported on socket (POSIX.1)
>>> ...
>>> ENOTSUP Operation not supported (POSIX.1)
>>>
>>
>> Yeah, other places in kernel use ENOTSUPP. This seems to be out of
>> line. And since the issue is long-existing, applications already know
>> how to deal with it. I should have made that argument. Change it to
>> ENOTSUPP.
>
> When I make the change, checkpatch says...
>
> WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP
> #128: FILE: arch/x86/kernel/cet_prctl.c:33:
> + return -ENOTSUPP;
>
> Do we want to reconsider?
I'm not sure I trust checkpatch over manpages. I had to google "SUSV4".
I'm not sure it matters at *all* for a 100% Linux-specific interface.
ENOTSUPP does seem less popular lately:
> $ git diff v5.0.. kernel/ arch/ drivers/ | grep ^+.*return.*E.*NO.*SUP.*\; | grep -o -- -E.*\; | sort | uniq -c | sort -n
> ... noise
> 61 -EOPNOTSUPP);
> 260 -ENOTSUPP;
> 1577 -EOPNOTSUPP;
but far from unused. That might be due to checkpatch spew more than
anything.
next prev parent reply other threads:[~2021-02-03 22:11 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 21:24 [PATCH v18 00/25] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 01/25] Documentation/x86: Add CET description Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 02/25] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection Yu-cheng Yu
2021-01-29 19:42 ` Dave Hansen
2021-01-29 19:58 ` Andy Lutomirski
2021-01-29 20:33 ` Dave Hansen
2021-01-29 20:46 ` Borislav Petkov
2021-01-29 21:13 ` Yu, Yu-cheng
2021-01-29 20:00 ` Yu, Yu-cheng
2021-01-27 21:25 ` [PATCH v18 03/25] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 04/25] x86/cpufeatures: Introduce X86_FEATURE_CET and setup functions Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 05/25] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-01-29 21:00 ` [NEEDS-REVIEW] " Dave Hansen
2021-01-29 22:35 ` Yu, Yu-cheng
2021-01-29 22:53 ` Dave Hansen
2021-02-01 22:43 ` Yu, Yu-cheng
2021-02-01 22:59 ` Dave Hansen
2021-02-01 23:05 ` Yu, Yu-cheng
2021-02-01 23:12 ` Dave Hansen
2021-02-01 23:14 ` Yu, Yu-cheng
2021-01-27 21:25 ` [PATCH v18 06/25] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 07/25] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 08/25] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 09/25] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 10/25] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 11/25] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 12/25] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 13/25] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 14/25] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 15/25] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 16/25] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 17/25] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 18/25] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 19/25] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 20/25] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 21/25] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-02-01 22:53 ` Dave Hansen
2021-02-01 22:58 ` Yu, Yu-cheng
2021-01-27 21:25 ` [PATCH v18 22/25] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 23/25] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-01-27 21:25 ` [PATCH v18 24/25] x86/cet/shstk: Add arch_prctl functions for " Yu-cheng Yu
2021-01-29 17:07 ` Dave Hansen
2021-01-29 18:56 ` Yu, Yu-cheng
2021-01-29 19:15 ` Dave Hansen
2021-01-29 19:53 ` Yu, Yu-cheng
2021-02-03 21:54 ` Yu, Yu-cheng
2021-02-03 22:11 ` Dave Hansen [this message]
2021-02-03 22:28 ` Yu, Yu-cheng
2021-01-27 21:25 ` [PATCH v18 25/25] mm: Introduce PROT_SHSTK " Yu-cheng Yu
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