linux-kernel - Re: [PATCH] lockdep: Noinstr annotate warn_bogus_irq

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Date:   Tue, 9 Feb 2021 17:03:46 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH] lockdep: Noinstr annotate warn_bogus_irq_restore()

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 <peterz@...radead.org>
> > 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 <rdunlap@...radead.org>
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> 
> Whoops; sorry for missing that!
> 
> Acked-by: Mark Rutland <mark.rutland@....com>

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 <peterz@...radead.org>
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 <rdunlap@...radead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Mark Rutland <mark.rutland@....com>
---
 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);