[PATCH 1/2] x86: initialize stack canary in secondary start

[PATCH 1/2] x86: initialize stack canary in secondary start

[Pan, Jacob jun]

>From 06503838368350268a46528e134c1dad9f4f8c93 Mon Sep 17 00:00:00 2001
From: Jacob Pan <jacob.jun.pan@intel.com>
Date: Thu, 17 Sep 2009 07:36:43 -0700
Subject: [PATCH 1/2] x86: initialize stack canary in secondary start

some secondary clockevent setup code needs to call request_irq, which will
cause fake stack check failure in schedule() if voluntary preemption
model is chosen, it is safe to have stack canary initialized here early,
since start_secondary() does not return.

Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
---
 arch/x86/kernel/smpboot.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 678d0b8..56ce974 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -48,6 +48,7 @@
 #include <linux/err.h>
 #include <linux/nmi.h>
 #include <linux/tboot.h>
+#include <linux/stackprotector.h>
 
 #include <asm/acpi.h>
 #include <asm/desc.h>
@@ -324,6 +325,9 @@ notrace static void __cpuinit start_secondary(void *unused)
 	/* enable local interrupts */
 	local_irq_enable();
 
+	/* to prevent fake stack check failure in clock setup */
+	boot_init_stack_canary();
+
 	x86_cpuinit.setup_percpu_clockev();
 
 	wmb();
-- 
1.6.5.3

Re: [PATCH 1/2] x86: initialize stack canary in secondary start

[Thomas Gleixner]

On Thu, 17 Dec 2009, Pan, Jacob jun wrote:
> >From 06503838368350268a46528e134c1dad9f4f8c93 Mon Sep 17 00:00:00 2001
> From: Jacob Pan <jacob.jun.pan@intel.com>
> Date: Thu, 17 Sep 2009 07:36:43 -0700
> Subject: [PATCH 1/2] x86: initialize stack canary in secondary start
> 
> some secondary clockevent setup code needs to call request_irq, which will
> cause fake stack check failure in schedule() if voluntary preemption
> model is chosen, it is safe to have stack canary initialized here early,
> since start_secondary() does not return.

Where is it initialized now ? Shouldnt the current init be removed ?

Thanks,

	tglx

> Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
> ---
>  arch/x86/kernel/smpboot.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 678d0b8..56ce974 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -48,6 +48,7 @@
>  #include <linux/err.h>
>  #include <linux/nmi.h>
>  #include <linux/tboot.h>
> +#include <linux/stackprotector.h>
>  
>  #include <asm/acpi.h>
>  #include <asm/desc.h>
> @@ -324,6 +325,9 @@ notrace static void __cpuinit start_secondary(void *unused)
>  	/* enable local interrupts */
>  	local_irq_enable();
>  
> +	/* to prevent fake stack check failure in clock setup */
> +	boot_init_stack_canary();
> +
>  	x86_cpuinit.setup_percpu_clockev();
>  
>  	wmb();
> -- 
> 1.6.5.3
> 
> 

RE: [PATCH 1/2] x86: initialize stack canary in secondary start

[Pan, Jacob jun]

>-----Original Message-----
>From: Thomas Gleixner [mailto:tglx@linutronix.de]
>Sent: Friday, December 18, 2009 8:03 AM
>To: Pan, Jacob jun
>Cc: H. Peter Anvin; x86@kernel.org; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH 1/2] x86: initialize stack canary in secondary start
>
>On Thu, 17 Dec 2009, Pan, Jacob jun wrote:
>> >From 06503838368350268a46528e134c1dad9f4f8c93 Mon Sep 17 00:00:00 2001
>> From: Jacob Pan <jacob.jun.pan@intel.com>
>> Date: Thu, 17 Sep 2009 07:36:43 -0700
>> Subject: [PATCH 1/2] x86: initialize stack canary in secondary start
>>
>> some secondary clockevent setup code needs to call request_irq, which will
>> cause fake stack check failure in schedule() if voluntary preemption
>> model is chosen, it is safe to have stack canary initialized here early,
>> since start_secondary() does not return.
>
>Where is it initialized now ? Shouldnt the current init be removed ?
>
[[JPAN]] it is currently in cpu_idle(), i don't think it can be removed since
there are other path calling it. calling boot_init_stack_canary() is redundant
in some case but harmless.

>Thanks,
>
>	tglx
>
>> Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
>> ---
>>  arch/x86/kernel/smpboot.c |    4 ++++
>>  1 files changed, 4 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
>> index 678d0b8..56ce974 100644
>> --- a/arch/x86/kernel/smpboot.c
>> +++ b/arch/x86/kernel/smpboot.c
>> @@ -48,6 +48,7 @@
>>  #include <linux/err.h>
>>  #include <linux/nmi.h>
>>  #include <linux/tboot.h>
>> +#include <linux/stackprotector.h>
>>
>>  #include <asm/acpi.h>
>>  #include <asm/desc.h>
>> @@ -324,6 +325,9 @@ notrace static void __cpuinit start_secondary(void
>*unused)
>>  	/* enable local interrupts */
>>  	local_irq_enable();
>>
>> +	/* to prevent fake stack check failure in clock setup */
>> +	boot_init_stack_canary();
>> +
>>  	x86_cpuinit.setup_percpu_clockev();
>>
>>  	wmb();
>> --
>> 1.6.5.3
>>
>>