Re: [PATCH v3 4/4] parisc: add support for TOC (transfer of control)

[Helge Deller <deller@gmx.de>]

On 10/16/21 18:49, Rolf Eike Beer wrote:
> Sven Schnelle wrote:
>
>> diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
>> index 27a8b49af11f..97a889eaffe1 100644
>> --- a/arch/parisc/Kconfig
>> +++ b/arch/parisc/Kconfig
>> @@ -288,6 +288,20 @@ config SMP
>>
>>  	  If you don't know what to do here, say N.
>>
>> +config TOC
>> +	bool "Support TOC switch"
>> +	default y if 64BIT || !SMP
>> +	help
>> +	  Most PA-RISC machines have either a switch at the back of the
> machine
>> +	  or a command in BMC to trigger a TOC interrupt. If you say Y here
> a
>> +	  handler will be installed which will either show a backtrace on
> all
>> +	  CPUs, or enter a possible configured debugger like kgdb/kdb.
>> +
>> +	  Note that with this option enabled, the kernel will use an
> additional
>> 16KB +	  per possible CPU as a special stack for the TOC handler.
>> +
>> +	  If you don't want to debug the Kernel, so N.
>
> so -> say?

Yes, I fixed that before I applied to my tree.

>> +void notrace __noreturn __cold toc_intr(struct pt_regs *regs)
>> +{
>> +	struct pdc_toc_pim_20 pim_data20;
>> +	struct pdc_toc_pim_11 pim_data11;
>> +
>> +	nmi_enter();
>> +
>> +	if (boot_cpu_data.cpu_type >= pcxu) {
>> +		if (pdc_pim_toc20(&pim_data20))
>> +			panic("Failed to get PIM data");
>> +		toc20_to_pt_regs(regs, &pim_data20);
>> +	} else {
>> +		if (pdc_pim_toc11(&pim_data11))
>> +			panic("Failed to get PIM data");
>> +		toc11_to_pt_regs(regs, &pim_data11);
>> +	}
>
> As I said elsewhere because I had missed v3: move the variables in the if
> branches.

It won't change anything, the compiler is clever enough to optimize it.
Another option would be to completely move the pdc_pim_toc* functions
into the toc*_to_pt_regs functions, maybe then renaming them to
get_tocXX_pt_regs(regs);

Helge