From: John David Anglin <dave.anglin@bell.net>
To: Helge Deller <deller@gmx.de>,
linux-parisc@vger.kernel.org,
James Bottomley <James.Bottomley@hansenpartnership.com>
Subject: Re: [PATCH][RFC] parisc: Use local tlb purges only on PA2.0 machines
Date: Sun, 25 Sep 2022 16:28:59 -0400 [thread overview]
Message-ID: <5f476a72-d2c0-8b0e-2446-13456a92e0bf@bell.net> (raw)
In-Reply-To: <1de28183-2252-04dc-9838-d695161a01ed@gmx.de>
On 2022-09-25 4:11 p.m., Helge Deller wrote:
> n 9/25/22 22:02, John David Anglin wrote:
>> On 2022-09-25 2:57 p.m., Helge Deller wrote:
>>> +#ifdef CONFIG_PA20
>>> +#define ALT_COND_PACACHE ALT_COND_ALWAYS
>>> +#else
>>> +#define ALT_COND_PACACHE ALT_COND_NO_SMP
>>> +#endif
>>> +
>>> ENTRY_CFI(flush_tlb_all_local)
>>> /*
>>> * The pitlbe and pdtlbe instructions should only be used to
>>> @@ -539,15 +545,10 @@ ENTRY_CFI(copy_user_page_asm)
>>>
>>> /* Purge any old translations */
>>>
>>> -#ifdef CONFIG_PA20
>>> - pdtlb,l %r0(%r28)
>>> - pdtlb,l %r0(%r29)
>>> -#else
>>> 0: pdtlb %r0(%r28)
>>> 1: pdtlb %r0(%r29)
>>> - ALTERNATIVE(0b, 0b+4, ALT_COND_NO_SMP, INSN_PxTLB)
>>> - ALTERNATIVE(1b, 1b+4, ALT_COND_NO_SMP, INSN_PxTLB)
>>> -#endif
>>> + ALTERNATIVE(0b, 0b+4, ALT_COND_PACACHE, INSN_PxTLB)
>>> + ALTERNATIVE(1b, 1b+4, ALT_COND_PACACHE, INSN_PxTLB)
>> This doesn't look correct. If ALT_COND_PACACHE is defined as ALT_COND_NO_SMP, the pdtlb
>> instructions will be converted to pdtlb,l instructions when running UP. These are not supported
>> on PA 1.1.
>
> Your concern is correct, but there is an additonal check in the alternative-coding,
> which prevents enabling the local flag if we're not running on a PA2.0 CPU.
> So, those ALTERNATIVE() macros will only apply on PA2.0 machines.
You are correct. Missed that.
That only leaves the bus serialization issue when pdtlb is used on an SMP machine.
Dave
--
John David Anglin dave.anglin@bell.net
next prev parent reply other threads:[~2022-09-25 20:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-25 18:57 [PATCH][RFC] parisc: Use local tlb purges only on PA2.0 machines Helge Deller
2022-09-25 20:02 ` John David Anglin
2022-09-25 20:11 ` Helge Deller
2022-09-25 20:28 ` John David Anglin [this message]
2022-09-27 20:06 ` Helge Deller
2022-09-27 22:06 ` John David Anglin
2022-09-28 9:25 ` Helge Deller
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