On Tue, Sep 08, 2020 at 05:41:57PM +0200, pet...@infradead.org wrote:
> On Tue, Sep 08, 2020 at 07:40:23AM -0700, Guenter Roeck wrote:
> > qemu-system-sparc64 -M sun4u -cpu "TI UltraSparc IIi" -m 512 \
> > -initrd rootfs.cpio \
> > -kernel arch/sparc/boot/image -no-reboot \
> > -append "panic=-1 slub_debug=FZPUA rdinit=/sbin/init console=ttyS0" \
> > -nographic -monitor none
>
> Thanks I got it. Also enabling DEBUG_LOCKDEP helps (-:
>
> ---
> Subject: sparc64: Fix irqtrace warnings on Ultra-S
>
> Recent changes in Lockdep's IRQTRACE broke Ultra-S.
>
> In order avoid redundant IRQ state changes, local_irq_restore() lost the
> ability to trace a disable. Change the code to use local_irq_save() to
> disable IRQs and then use arch_local_irq_restore() to further disable
> NMIs.
>
> This result in slightly suboptimal code, but given this code uses a
> global spinlock, performance cannot be its primary purpose.
>
> Fixes: 044d0d6de9f5 ("lockdep: Only trace IRQ edges")
> Reported-by: Guenter Roeck <li...@roeck-us.net>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Tested-by: Guenter Roeck <li...@roeck-us.net>
> ---
> A possible alternative would be:
>
> local_save_flags(flags);
> arch_local_irq_restore((unsigned long)PIL_NMI);
> if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS))
> trace_hardirqs_off();
>
> which generates optimal code, but is more verbose.
>
> arch/sparc/prom/p1275.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/arch/sparc/prom/p1275.c b/arch/sparc/prom/p1275.c
> index 889aa602f8d8..e22233fcf741 100644
> --- a/arch/sparc/prom/p1275.c
> +++ b/arch/sparc/prom/p1275.c
> @@ -37,16 +37,15 @@ void p1275_cmd_direct(unsigned long *args)
> {
> unsigned long flags;
>
> - local_save_flags(flags);
> - local_irq_restore((unsigned long)PIL_NMI);
> + local_irq_save(flags);
> + arch_local_irq_restore((unsigned long)PIL_NMI);
> raw_spin_lock(&prom_entry_lock);
>
> prom_world(1);
> prom_cif_direct(args);
> prom_world(0);
>
> - raw_spin_unlock(&prom_entry_lock);
> - local_irq_restore(flags);
> + raw_spin_unlock_irqrestore(&prom_entry_lock, flags);
> }
>
> void prom_cif_init(void *cif_handler, void *cif_stack)
