From: Andreas Schwab <schwab@linux-m68k.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linuxppc-dev@lists.ozlabs.org, Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH] powerpc/64s: power4 nap fixup in C
Date: Mon, 29 Mar 2021 13:56:28 +0200 [thread overview]
Message-ID: <87czvikwb7.fsf@igel.home> (raw)
In-Reply-To: <236a67a4-1609-5fec-3c68-41db02cd1a4c__18973.8760514714$1617008745$gmane$org@csgroup.eu> (Christophe Leroy's message of "Mon, 29 Mar 2021 11:04:52 +0200")
On Mär 29 2021, Christophe Leroy wrote:
> Le 29/03/2021 à 10:33, Benjamin Herrenschmidt a écrit :
>> On Fri, 2021-03-12 at 11:20 +1000, Nicholas Piggin wrote:
>>>
>>> +static inline void nap_adjust_return(struct pt_regs *regs)
>>>
>>> +{
>>>
>>> +#ifdef CONFIG_PPC_970_NAP
>>>
>>> + if (unlikely(test_thread_local_flags(_TLF_NAPPING))) {
>>> + /* Can avoid a test-and-clear because NMIs do not call this */
>>> + clear_thread_local_flags(_TLF_NAPPING);
>>> + regs->nip = (unsigned long)power4_idle_nap_return;
>>> + }
>> Is this a pointer to a function descriptor or the actual code ?
>>
>
> --- a/arch/powerpc/kernel/idle_book3s.S
> +++ b/arch/powerpc/kernel/idle_book3s.S
> @@ -209,4 +209,8 @@ _GLOBAL(power4_idle_nap)
> mtmsrd r7
> isync
> b 1b
> +
> + .globl power4_idle_nap_return
> +power4_idle_nap_return:
> + blr
> #endif
The problem is not the definition, it is the reference. In C, a
function symbol always resolves to the address of the descriptor.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
next prev parent reply other threads:[~2021-03-29 11:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 1:20 [PATCH] powerpc/64s: power4 nap fixup in C Nicholas Piggin
2021-03-16 7:16 ` Christophe Leroy
2021-03-16 8:11 ` Nicholas Piggin
2021-03-29 4:40 ` Michael Ellerman
2021-03-29 8:33 ` Benjamin Herrenschmidt
2021-03-29 9:04 ` Christophe Leroy
[not found] ` <236a67a4-1609-5fec-3c68-41db02cd1a4c__18973.8760514714$1617008745$gmane$org@csgroup.eu>
2021-03-29 11:56 ` Andreas Schwab [this message]
[not found] ` <87czvikwb7.fsf__13924.9042653077$1617019017$gmane$org@igel.home>
2021-03-29 16:51 ` Andreas Schwab
[not found] ` <87y2e6fu7v.fsf__9754.75274478725$1616992871$gmane$org@mpe.ellerman.id.au>
2021-03-29 15:30 ` Andreas Schwab
[not found] ` <87v99aj7tr.fsf__47134.2879392736$1617031867$gmane$org@igel.home>
2021-03-29 16:23 ` Andreas Schwab
2021-04-01 7:36 ` Nicholas Piggin
2021-04-05 12:56 ` Nicholas Piggin
2021-04-05 16:40 ` Andreas Schwab
2021-04-06 2:45 ` Nicholas Piggin
2021-04-10 14:28 ` Michael Ellerman
2021-04-19 5:16 ` Michael Ellerman
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