From: Borislav Petkov <bp@alien8.de>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: 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@amacapital.net>,
Balbir Singh <bsingharora@gmail.com>,
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>
Subject: Re: [RFC PATCH v6 04/26] x86/fpu/xstate: Introduce XSAVES system states
Date: Tue, 4 Dec 2018 17:01:45 +0100 [thread overview]
Message-ID: <20181204160144.GG11803@zn.tnic> (raw)
In-Reply-To: <20181119214809.6086-5-yu-cheng.yu@intel.com>
On Mon, Nov 19, 2018 at 01:47:47PM -0800, Yu-cheng Yu wrote:
> Control-flow Enforcement (CET) MSR contents are XSAVES system states.
> To support CET, introduce XSAVES system states first.
>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> ---
> arch/x86/include/asm/fpu/internal.h | 3 +-
> arch/x86/include/asm/fpu/xstate.h | 4 +-
> arch/x86/kernel/fpu/core.c | 6 +-
> arch/x86/kernel/fpu/init.c | 10 ---
> arch/x86/kernel/fpu/xstate.c | 94 +++++++++++++++++++----------
> 5 files changed, 69 insertions(+), 48 deletions(-)
...
> @@ -704,6 +710,7 @@ static int init_xstate_size(void)
> */
> static void fpu__init_disable_system_xstate(void)
> {
> + xfeatures_mask_all = 0;
> xfeatures_mask_user = 0;
> cr4_clear_bits(X86_CR4_OSXSAVE);
> fpu__xstate_clear_all_cpu_caps();
> @@ -717,6 +724,8 @@ void __init fpu__init_system_xstate(void)
> {
> unsigned int eax, ebx, ecx, edx;
> static int on_boot_cpu __initdata = 1;
> + u64 cpu_system_xfeatures_mask;
> + u64 cpu_user_xfeatures_mask;
So what I had in mind is to not have those local vars but use
xfeatures_mask_user and xfeatures_mask_system here directly...
> int err;
> int i;
>
> @@ -739,10 +748,23 @@ void __init fpu__init_system_xstate(void)
> return;
> }
>
> + /*
> + * Find user states supported by the processor.
> + * Only these bits can be set in XCR0.
> + */
> cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
> - xfeatures_mask_user = eax + ((u64)edx << 32);
> + cpu_user_xfeatures_mask = eax + ((u64)edx << 32);
>
> - if ((xfeatures_mask_user & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
> + /*
> + * Find system states supported by the processor.
> + * Only these bits can be set in IA32_XSS MSR.
> + */
> + cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
> + cpu_system_xfeatures_mask = ecx + ((u64)edx << 32);
> +
> + xfeatures_mask_all = cpu_user_xfeatures_mask | cpu_system_xfeatures_mask;
... and not introduce xfeatures_mask_all at all but everywhere you need
all features, to do:
(xfeatures_mask_user | xfeatures_mask_system)
and work with that.
...
> @@ -1178,7 +1208,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
> * The state that came in from userspace was user-state only.
> * Mask all the user states out of 'xfeatures':
> */
> - xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
> + xsave->header.xfeatures &= (xfeatures_mask_all & ~xfeatures_mask_user);
... and this would be
xsave->header.xfeatures &= xfeatures_mask_system;
>
> /*
> * Add back in the features that came in from userspace:
> @@ -1234,7 +1264,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
> * The state that came in from userspace was user-state only.
> * Mask all the user states out of 'xfeatures':
> */
> - xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
> + xsave->header.xfeatures &= (xfeatures_mask_all & ~xfeatures_mask_user);
Ditto here.
This way you have *two* mask variables and code queries them only.
Hmmm?
Or am I missing something?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-12-04 16:01 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 21:47 [RFC PATCH v6 00/26] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 01/26] Documentation/x86: Add CET description Yu-cheng Yu
2018-11-20 9:52 ` Ingo Molnar
2018-11-20 20:36 ` Yu-cheng Yu
2018-11-21 7:24 ` Ingo Molnar
2018-11-19 21:47 ` [RFC PATCH v6 02/26] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 03/26] x86/fpu/xstate: Change names to separate XSAVES system and user states Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 04/26] x86/fpu/xstate: Introduce XSAVES system states Yu-cheng Yu
2018-12-04 16:01 ` Borislav Petkov [this message]
2018-12-04 17:08 ` Yu-cheng Yu
2018-12-04 18:16 ` Borislav Petkov
2018-11-19 21:47 ` [RFC PATCH v6 05/26] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 06/26] x86/cet: Add control protection exception handler Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 07/26] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 08/26] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 09/26] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 10/26] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 11/26] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 12/26] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 13/26] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 14/26] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 15/26] mm: Handle shadow stack page fault Yu-cheng Yu
2018-11-19 21:47 ` [RFC PATCH v6 16/26] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 17/26] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 18/26] mm: Introduce do_mmap_locked() Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 19/26] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 20/26] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 21/26] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 22/26] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2019-04-25 11:02 ` Dave Martin
2019-04-25 15:14 ` Yu-cheng Yu
2019-04-25 15:35 ` Dave Martin
2019-04-25 16:11 ` Dave Martin
2019-04-25 16:20 ` Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 23/26] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 24/26] mm/mmap: Add Shadow stack pages to memory accounting Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 25/26] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2018-11-19 21:48 ` [RFC PATCH v6 26/26] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2018-11-22 16:53 ` [RFC PATCH v6 00/26] Control-flow Enforcement: Shadow Stack Andy Lutomirski
2018-11-26 17:38 ` Yu-cheng Yu
2018-11-26 18:29 ` Andy Lutomirski
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