linux-kernel - Re: [PATCH RFC 1/2] m68k: Add tracirqs

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Message-ID: <4ab85330-5a50-bde1-f014-99a8e7cb28cc@gmail.com>
Date: Wed, 23 Oct 2024 16:53:58 +1300
From: Michael Schmitz <schmitzmic@...il.com>
To: Jean-Michel Hautbois <jeanmichel.hautbois@...eli.org>,
 Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, rostedt@...dmis.org
Subject: Re: [PATCH RFC 1/2] m68k: Add tracirqs

Jean-Michel,

thanks for your patches!

Am 21.10.2024 um 22:44 schrieb Jean-Michel Hautbois:
> The TRACE_IRQFLAGS_SUPPORT requires the architecture to call
> trace_hardirqs_off() when interrupts are disabled and
> trace_hardirqs_on() when they are enabled.
> Add those calls to do_IRQ function.

You will also have to add these calls to the three sites in 
arch/m68k/coldfire/head.S where interrupts are enabled or disabled.

Here:
> ENTRY(system_call)
>         SAVE_ALL_SYS
>         move    #0x2000,%sr             /* enable intrs again */
>         GET_CURRENT(%d2)

and here:
> ret_from_exception:
>         move    #0x2700,%sr             /* disable intrs */
>         btst    #5,%sp@(PT_OFF_SR)      /* check if returning to kernel */
>         jeq     Luser_return            /* if so, skip resched, signals */

and here:
> Lwork_to_do:
>         movel   %a0@(TINFO_FLAGS),%d1   /* get thread_info->flags */
>         move    #0x2000,%sr             /* enable intrs again */
>         btst    #TIF_NEED_RESCHED,%d1
>         jne     reschedule

There's one similar site in arch/m68k/kernel/head.S (ret_from_exception) 
where interrupts are enabled that would need a similar change, if you 
want to enable this for all m68k.

Registers %d0-%d5 and %a0-%a2 are saved on the stack at this point and 
can be clobbered if need be.

Cheers,

	Michael


>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@...eli.org>
> ---
>  arch/m68k/Kconfig      | 1 +
>  arch/m68k/kernel/irq.c | 2 ++
>  2 files changed, 3 insertions(+)
>
> diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
> index cc26df907bfe3c8143a931d259eceabb16af7411..ab3375475721fa63418c40d4ba6ac76679ebc77d 100644
> --- a/arch/m68k/Kconfig
> +++ b/arch/m68k/Kconfig
> @@ -39,6 +39,7 @@ config M68K
>  	select OLD_SIGSUSPEND3
>  	select UACCESS_MEMCPY if !MMU
>  	select ZONE_DMA
> +	select TRACE_IRQFLAGS_SUPPORT
>
>  config CPU_BIG_ENDIAN
>  	def_bool y
> diff --git a/arch/m68k/kernel/irq.c b/arch/m68k/kernel/irq.c
> index 9ab4f550342e5de11c528f55781432675ffd66bf..74cf60ebbc4bca51f3caa4046dbd2bdb02355711 100644
> --- a/arch/m68k/kernel/irq.c
> +++ b/arch/m68k/kernel/irq.c
> @@ -21,9 +21,11 @@ asmlinkage void do_IRQ(int irq, struct pt_regs *regs)
>  {
>  	struct pt_regs *oldregs = set_irq_regs(regs);
>
> +	trace_hardirqs_off();
>  	irq_enter();
>  	generic_handle_irq(irq);
>  	irq_exit();
> +	trace_hardirqs_on();
>
>  	set_irq_regs(oldregs);
>  }
>