From: Thomas Gleixner <tglx@linutronix.de>
To: ira.weiny@intel.com, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Fenghua Yu <fenghua.yu@intel.com>,
linux-doc@vger.kernel.org, linux-nvdimm@lists.01.org,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH V3 06/10] x86/entry: Preserve PKRS MSR across exceptions
Date: Thu, 17 Dec 2020 16:28:51 +0100 [thread overview]
Message-ID: <87y2hwqwng.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201106232908.364581-7-ira.weiny@intel.com>
On Fri, Nov 06 2020 at 15:29, ira weiny wrote:
> +#ifdef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS
> +/*
> + * PKRS is a per-logical-processor MSR which overlays additional protection for
> + * pages which have been mapped with a protection key.
> + *
> + * The register is not maintained with XSAVE so we have to maintain the MSR
> + * value in software during context switch and exception handling.
> + *
> + * Context switches save the MSR in the task struct thus taking that value to
> + * other processors if necessary.
> + *
> + * To protect against exceptions having access to this memory we save the
> + * current running value and set the PKRS value for the duration of the
> + * exception. Thus preventing exception handlers from having the elevated
> + * access of the interrupted task.
> + */
> +noinstr void irq_save_set_pkrs(irqentry_state_t *irq_state, u32 val)
> +{
> + if (!cpu_feature_enabled(X86_FEATURE_PKS))
> + return;
> +
> + irq_state->thread_pkrs = current->thread.saved_pkrs;
> + write_pkrs(INIT_PKRS_VALUE);
Why is this noinstr? Just because it's called from a noinstr function?
Of course the function itself violates the noinstr constraints:
vmlinux.o: warning: objtool: write_pkrs()+0x36: call to do_trace_write_msr() leaves .noinstr.text section
There is absolutely no reason to have this marked noinstr.
Thanks,
tglx
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next prev parent reply other threads:[~2020-12-17 15:28 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 23:28 [PATCH V3 00/10] PKS: Add Protection Keys Supervisor (PKS) support V3 ira.weiny
2020-11-06 23:28 ` [PATCH V3 01/10] x86/pkeys: Create pkeys_common.h ira.weiny
2020-11-06 23:29 ` [PATCH V3 02/10] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2020-11-06 23:29 ` [PATCH V3 03/10] x86/pks: Add PKS defines and Kconfig options ira.weiny
2020-11-06 23:29 ` [PATCH V3 04/10] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2020-12-17 14:50 ` Thomas Gleixner
2020-12-17 22:43 ` Thomas Gleixner
2020-12-18 13:57 ` Thomas Gleixner
2020-12-18 19:20 ` Dan Williams
2020-12-18 21:06 ` Thomas Gleixner
2020-12-18 21:58 ` Dan Williams
2020-12-18 22:44 ` Thomas Gleixner
2020-12-18 19:42 ` Ira Weiny
2020-12-18 20:10 ` Dave Hansen
2020-12-18 21:30 ` Thomas Gleixner
2020-12-18 4:05 ` Ira Weiny
2020-12-17 20:41 ` [NEEDS-REVIEW] " Dave Hansen
2020-12-18 4:10 ` Ira Weiny
2020-12-18 15:33 ` Dave Hansen
2020-11-06 23:29 ` [PATCH V3 05/10] x86/entry: Pass irqentry_state_t by reference ira.weiny
2020-11-15 18:58 ` Thomas Gleixner
2020-11-16 18:49 ` Ira Weiny
2020-11-16 20:36 ` Thomas Gleixner
2020-11-24 6:09 ` [PATCH V3.1] entry: " ira.weiny
2020-12-11 22:14 ` Andy Lutomirski
2020-12-16 1:32 ` Ira Weiny
2020-12-16 2:09 ` Andy Lutomirski
2020-12-17 0:38 ` Ira Weiny
2020-12-17 13:07 ` Thomas Gleixner
2020-12-17 13:19 ` Peter Zijlstra
2020-12-17 15:35 ` Andy Lutomirski
2020-12-17 16:58 ` Thomas Gleixner
2020-11-06 23:29 ` [PATCH V3 06/10] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2020-12-17 15:28 ` Thomas Gleixner [this message]
2020-11-06 23:29 ` [PATCH V3 07/10] x86/fault: Report the PKRS state on fault ira.weiny
2020-11-06 23:29 ` [PATCH V3 08/10] x86/pks: Add PKS kernel API ira.weiny
2020-12-23 20:39 ` Randy Dunlap
2020-11-06 23:29 ` [PATCH V3 09/10] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny
2020-11-06 23:29 ` [PATCH V3 10/10] x86/pks: Add PKS test code ira.weiny
2020-12-17 20:55 ` Dave Hansen
2020-12-18 4:05 ` Ira Weiny
2020-12-18 16:59 ` Dan Williams
2020-12-07 22:14 ` [PATCH V3 00/10] PKS: Add Protection Keys Supervisor (PKS) support V3 Ira Weiny
2020-12-08 15:55 ` Thomas Gleixner
2020-12-08 17:22 ` Ira Weiny
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