From: Florian Weimer <fweimer@redhat.com>
To: "Yu, Yu-cheng" <yu-cheng.yu@intel.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
Dave Martin <Dave.Martin@arm.com>,
Dave Hansen <dave.hansen@intel.com>,
Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
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>,
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>,
Weijiang Yang <weijiang.yang@intel.com>
Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack
Date: Tue, 01 Sep 2020 20:17:26 +0200 [thread overview]
Message-ID: <87k0xdqs3t.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <b84e6fae-5d51-b0a0-d917-76f86b3186b7@intel.com> (Yu-cheng Yu's message of "Tue, 1 Sep 2020 10:58:25 -0700")
* Yu-cheng Yu:
> On 9/1/2020 10:50 AM, Florian Weimer wrote:
>> * Yu-cheng Yu:
>>
>>> Like other arch_prctl()'s, this parameter was 'unsigned long'
>>> earlier. The idea was, since this arch_prctl is only implemented for
>>> the 64-bit kernel, we wanted it to look as 64-bit only. I will change
>>> it back to 'unsigned long'.
>> What about x32? In general, long is rather problematic for x32.
>
> The problem is the size of 'long', right?
> Because this parameter is passed in a register, and only the lower
> bits are used, x32 works as well.
The userspace calling convention leaves the upper 32-bit undefined.
Therefore, this only works by accident if the kernel does not check that
the upper 32-bit are zero, which is probably a kernel bug.
It's unclear to me what you are trying to accomplish. Why do you want
to use unsigned long here? The correct type appears to be unsigned int.
This correctly expresses that the upper 32 bits of the register do not
matter.
Thanks,
Florian
next prev parent reply other threads:[~2020-09-01 18:17 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 0:25 [PATCH v11 00/25] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 01/25] Documentation/x86: Add CET description Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 02/25] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 03/25] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 04/25] x86/cet: Add control-protection fault handler Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 05/25] x86/cet/shstk: Add Kconfig option for user-mode Shadow Stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 06/25] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 07/25] x86/mm: Remove _PAGE_DIRTY_HW from kernel RO pages Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 08/25] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 09/25] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 10/25] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 11/25] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY_HW to _PAGE_COW Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 12/25] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 13/25] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 14/25] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 15/25] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 16/25] mm: Add guard pages around a shadow stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 17/25] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 18/25] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 19/25] mm: Re-introduce do_mmap_pgoff() Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 20/25] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 21/25] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 22/25] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND properties Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 23/25] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 24/25] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2020-08-25 0:25 ` [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for " Yu-cheng Yu
2020-08-25 0:36 ` Andy Lutomirski
2020-08-25 18:43 ` Yu, Yu-cheng
2020-08-25 19:19 ` Dave Hansen
2020-08-25 21:04 ` Yu, Yu-cheng
2020-08-25 23:20 ` Dave Hansen
2020-08-25 23:34 ` Yu, Yu-cheng
2020-08-26 16:46 ` Dave Martin
2020-08-26 16:51 ` Florian Weimer
2020-08-26 17:04 ` Andy Lutomirski
2020-08-26 18:49 ` Yu, Yu-cheng
2020-08-26 19:43 ` H.J. Lu
2020-08-26 19:57 ` Dave Hansen
2020-08-27 13:26 ` H.J. Lu
2020-09-01 10:28 ` Dave Martin
2020-09-01 17:23 ` Yu, Yu-cheng
2020-09-01 17:45 ` Andy Lutomirski
2020-09-01 18:11 ` Dave Hansen
2020-09-02 13:58 ` Dave Martin
2020-09-08 17:50 ` Yu, Yu-cheng
2020-09-08 17:57 ` Dave Hansen
2020-09-08 18:25 ` Yu, Yu-cheng
2020-09-09 22:08 ` Yu, Yu-cheng
2020-09-09 22:59 ` Dave Hansen
2020-09-09 23:07 ` Yu, Yu-cheng
2020-09-09 23:11 ` Dave Hansen
2020-09-09 23:25 ` Yu, Yu-cheng
2020-09-09 23:29 ` Dave Hansen
2020-09-09 23:45 ` Yu, Yu-cheng
2020-09-11 22:59 ` Yu-cheng Yu
2020-09-14 14:50 ` [NEEDS-REVIEW] " Dave Hansen
2020-09-14 18:31 ` Andy Lutomirski
2020-09-14 20:44 ` Yu, Yu-cheng
2020-09-14 21:14 ` Dave Hansen
2020-09-16 13:52 ` Andy Lutomirski
2020-09-16 19:25 ` Yu, Yu-cheng
2021-09-14 1:33 ` [NEEDS-REVIEW] " Edgecombe, Rick P
2021-09-14 9:53 ` Borislav Petkov
2021-09-20 16:48 ` Andy Lutomirski
2021-09-23 23:32 ` Edgecombe, Rick P
2020-09-15 0:12 ` Yu, Yu-cheng
2020-09-15 19:08 ` Yu-cheng Yu
2020-09-15 19:24 ` Dave Hansen
2020-09-15 20:16 ` Yu, Yu-cheng
2020-08-26 17:08 ` Dave Martin
2020-08-27 13:18 ` Florian Weimer
2020-08-27 13:28 ` H.J. Lu
2020-08-27 13:36 ` Florian Weimer
2020-08-27 14:07 ` H.J. Lu
2020-08-27 14:08 ` H.J. Lu
2020-09-01 17:49 ` Yu, Yu-cheng
2020-09-01 17:50 ` Florian Weimer
2020-09-01 17:58 ` Yu, Yu-cheng
2020-09-01 18:17 ` Florian Weimer [this message]
2020-09-01 18:19 ` H.J. Lu
2020-09-01 18:24 ` Yu, Yu-cheng
2020-08-27 18:13 ` Yu, Yu-cheng
2020-08-27 18:56 ` Andy Lutomirski
2020-08-27 19:33 ` Yu, Yu-cheng
2020-08-27 19:37 ` H.J. Lu
2020-08-28 1:35 ` Andy Lutomirski
2020-08-28 1:44 ` H.J. Lu
2020-08-28 6:23 ` Florian Weimer
2020-08-28 11:37 ` H.J. Lu
2020-08-28 17:39 ` Andy Lutomirski
2020-08-28 17:45 ` H.J. Lu
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