From: Ira Weiny <ira.weiny@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Fenghua Yu <fenghua.yu@intel.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH RFC V3 6/9] x86/entry: Pass irqentry_state_t by reference
Date: Sun, 18 Oct 2020 22:37:36 -0700 [thread overview]
Message-ID: <20201019053639.GA3713473@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <87lfg6tjnq.fsf@nanos.tec.linutronix.de>
On Fri, Oct 16, 2020 at 02:55:21PM +0200, Thomas Gleixner wrote:
> On Fri, Oct 16 2020 at 13:45, Peter Zijlstra wrote:
> > On Fri, Oct 09, 2020 at 12:42:55PM -0700, ira.weiny@intel.com wrote:
> >> @@ -238,7 +236,7 @@ noinstr void idtentry_exit_nmi(struct pt_regs *regs, bool restore)
> >>
> >> rcu_nmi_exit();
> >> lockdep_hardirq_exit();
> >> - if (restore)
> >> + if (irq_state->exit_rcu)
> >> lockdep_hardirqs_on(CALLER_ADDR0);
> >> __nmi_exit();
> >> }
> >
> > That's not nice.. The NMI path is different from the IRQ path and has a
> > different variable. Yes, this works, but *groan*.
> >
> > Maybe union them if you want to avoid bloating the structure, but the
> > above makes it really hard to read.
>
> Right, and also that nmi entry thing should not be in x86. Something
> like the untested below as first cleanup.
Ok, I see what Peter was talking about. I've added this patch to the series.
>
> Thanks,
>
> tglx
> ----
> Subject: x86/entry: Move nmi entry/exit into common code
> From: Thomas Gleixner <tglx@linutronix.de>
> Date: Fri, 11 Sep 2020 10:09:56 +0200
>
> Add blurb here.
How about:
To prepare for saving PKRS values across NMI's we lift the
idtentry_[enter|exit]_nmi() to the common code. Rename them to
irqentry_nmi_[enter|exit]() to reflect the new generic nature and store the
state in the same irqentry_state_t structure as the other irqentry_*()
functions. Finally, differentiate the state being stored between the NMI and
IRQ path by adding 'lockdep' to irqentry_state_t.
?
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/entry/common.c | 34 ----------------------------------
> arch/x86/include/asm/idtentry.h | 3 ---
> arch/x86/kernel/cpu/mce/core.c | 6 +++---
> arch/x86/kernel/nmi.c | 6 +++---
> arch/x86/kernel/traps.c | 13 +++++++------
> include/linux/entry-common.h | 20 ++++++++++++++++++++
> kernel/entry/common.c | 36 ++++++++++++++++++++++++++++++++++++
> 7 files changed, 69 insertions(+), 49 deletions(-)
>
[snip]
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -343,6 +343,7 @@ void irqentry_exit_to_user_mode(struct p
> #ifndef irqentry_state
> typedef struct irqentry_state {
> bool exit_rcu;
> + bool lockdep;
> } irqentry_state_t;
Building on what Peter said do you agree this should be made into a union?
It may not be strictly necessary in this patch but I think it would reflect the
mutual exclusivity better and could be changed easy enough in the follow on
patch which adds the pkrs state.
Ira
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next prev parent reply other threads:[~2020-10-19 5:37 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-09 19:42 [PATCH RFC V3 0/9] PKS: Add Protection Keys Supervisor (PKS) support RFC v3 ira.weiny
2020-10-09 19:42 ` [PATCH RFC V3 1/9] x86/pkeys: Create pkeys_common.h ira.weiny
2020-10-13 17:46 ` Dave Hansen
2020-10-13 19:44 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 2/9] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2020-10-13 17:50 ` Dave Hansen
2020-10-13 23:56 ` Ira Weiny
2020-10-16 10:57 ` Peter Zijlstra
2020-10-17 3:32 ` Ira Weiny
2020-10-19 9:35 ` Peter Zijlstra
2020-10-09 19:42 ` [PATCH RFC V3 3/9] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny
2020-10-13 18:23 ` Dave Hansen
2020-10-14 2:08 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 4/9] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2020-10-13 18:31 ` Dave Hansen
2020-10-14 22:36 ` Ira Weiny
2020-10-16 11:12 ` Peter Zijlstra
2020-10-17 5:14 ` Ira Weiny
2020-10-19 9:37 ` Peter Zijlstra
2020-10-19 18:48 ` Ira Weiny
2020-10-16 11:06 ` Peter Zijlstra
2020-10-17 5:37 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 5/9] x86/pks: Add PKS kernel API ira.weiny
2020-10-13 18:43 ` Dave Hansen
2020-10-15 1:08 ` Ira Weiny
2020-10-16 11:07 ` Peter Zijlstra
2020-10-17 5:42 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 6/9] x86/entry: Pass irqentry_state_t by reference ira.weiny
2020-10-16 11:45 ` Peter Zijlstra
2020-10-16 12:55 ` Thomas Gleixner
2020-10-19 5:37 ` Ira Weiny [this message]
2020-10-19 9:32 ` Thomas Gleixner
2020-10-19 20:26 ` Ira Weiny
2020-10-19 21:12 ` Thomas Gleixner
2020-10-20 14:10 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 7/9] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2020-10-13 18:52 ` Dave Hansen
2020-10-15 3:46 ` Ira Weiny
2020-10-15 4:06 ` Dave Hansen
2020-10-15 4:18 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 8/9] x86/fault: Report the PKRS state on fault ira.weiny
2020-10-13 18:56 ` Dave Hansen
2020-10-15 4:13 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 9/9] x86/pks: Add PKS test code ira.weiny
2020-10-13 19:02 ` Dave Hansen
2020-10-15 4:46 ` Ira Weiny
2020-10-09 20:18 ` [PATCH RFC V3 0/9] PKS: Add Protection Keys Supervisor (PKS) support RFC v3 Ira Weiny
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