Subject: Re: [PATCH] lockdep: Noinstr annotate warn_bogus_irq_restore()

From: Randy Dunlap <[email-masked]>
Date: Tue, 9 Feb 2021 10:28:33 -0800

On 2/9/21 8:03 AM, Peter Zijlstra wrote:
> On Tue, Feb 09, 2021 at 01:24:30PM +0000, Mark Rutland wrote:
>> On Tue, Feb 09, 2021 at 09:34:10AM +0100, Peter Zijlstra wrote:
>>>
>>> Subject: lockdep: Noinstr annotate warn_bogus_irq_restore()
>>> From: Peter Zijlstra <[email-masked]>
>>> Date: Tue Feb 9 09:30:03 CET 2021
>>>
>>>   vmlinux.o: warning: objtool: lock_is_held_type()+0x107: call to warn_bogus_irq_restore() leaves .noinstr.text section
>>>
>>> As per the general rule that WARNs are allowed to violate noinstr to
>>> get out, annotate it away.
>>>
>>> Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration")
>>> Reported-by: Randy Dunlap <[email-masked]>
>>> Signed-off-by: Peter Zijlstra (Intel) <[email-masked]>
>>
>> Whoops; sorry for missing that!
>>
>> Acked-by: Mark Rutland <[email-masked]>
> 
> This runs into sodding header hell on mips (and possibly others)
> 
> How's this then?
> 
> ---
> Subject: lockdep: Noinstr annotate warn_bogus_irq_restore()
> From: Peter Zijlstra <[email-masked]>
> Date: Tue Feb 9 09:30:03 CET 2021
> 
>   vmlinux.o: warning: objtool: lock_is_held_type()+0x107: call to warn_bogus_irq_restore() leaves .noinstr.text section
> 
> As per the general rule that WARNs are allowed to violate noinstr to
> get out, annotate it away.
> 
> Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration")
> Reported-by: Randy Dunlap <[email-masked]>
> Signed-off-by: Peter Zijlstra (Intel) <[email-masked]>
> Acked-by: Mark Rutland <[email-masked]>

Acked-by: Randy Dunlap <[email-masked]> # build-tested

Thanks.

> ---
>  include/linux/irqflags.h       |    5 ++++-
>  kernel/locking/irqflag-debug.c |    4 +++-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> --- a/kernel/locking/irqflag-debug.c
> +++ b/kernel/locking/irqflag-debug.c
> @@ -4,8 +4,10 @@
>  #include <linux/export.h>
>  #include <linux/irqflags.h>
>  
> -void warn_bogus_irq_restore(void)
> +noinstr void warn_bogus_irq_restore(void)
>  {
> +	instrumentation_begin();
>  	WARN_ONCE(1, "raw_local_irq_restore() called with IRQs enabled\n");
> +	instrumentation_end();
>  }
>  EXPORT_SYMBOL(warn_bogus_irq_restore);
> 

-- 
~Randy