linux-kernel - Re: [patch 1/6] hardirq: Make hardirq bits generic

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Date:	Thu, 19 Sep 2013 20:19:47 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Andreas Schwab <schwab@...ux-m68k.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linux-Arch <linux-arch@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <ak@...ux.intel.com>, Peter Anvin <hpa@...or.com>,
	Mike Galbraith <bitbucket@...ine.de>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"Linux/m68k" <linux-m68k@...r.kernel.org>
Subject: Re: [patch 1/6] hardirq: Make hardirq bits generic

On Thu, Sep 19, 2013 at 7:02 PM, Andreas Schwab <schwab@...ux-m68k.org> wrote:
> Thomas Gleixner <tglx@...utronix.de> writes:
>> +     /*
>> +      * Only the last interrupt leaving the kernel goes through the
>> +      * various exception return checks.
>> +      */
>> +     cmpl    #0, %d0
>         tstl    %d0

arch/m68k/kernel/built-in.o: In function `bad_inthandler':
(.text+0x2a6): undefined reference to `ret_from_last_interrupt'

I came up with the quick (whitespace-damaged-gmail) fix below.
Or should we handle the nesting in handle_badint(), too?

--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -313,17 +313,11 @@ user_irqvec_fixup = . + 2

 ENTRY(bad_inthandler)
        SAVE_ALL_INT
-       GET_CURRENT(%d0)
-       movel   %d0,%a1
-       addqb   #1,%a1@(TINFO_PREEMPT+1)

        movel   %sp,%sp@-
        jsr     handle_badint
        addql   #4,%sp

-       movel   %curptr@(TASK_STACK),%a1
-       subqb   #1,%a1@(TINFO_PREEMPT+1)
-       jeq     ret_from_last_interrupt
        RESTORE_ALL

However, the resulting kernel hangs (on ARAnyM) after starting userspace:

| INIT: version 2.86 booting

I'll have a deeper look when I have some more time...

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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