From: Thomas Gleixner <tglx@linutronix.de>
To: Christophe Leroy <christophe.leroy@c-s.fr>, luto@kernel.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
arnd@arndb.de, vincenzo.frascino@arm.com, x86@kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org
Subject: Re: [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
Date: Thu, 16 Jan 2020 11:35:17 +0100 [thread overview]
Message-ID: <87k15rwuxm.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <b5fddcf8-99ff-fc0d-40c0-0eb81ad4e94a@c-s.fr>
Christophe Leroy <christophe.leroy@c-s.fr> writes:
> Le 15/01/2020 à 07:15, Christophe Leroy a écrit :
> From your point of view, what should I do:
> A/ __arch_get_vdso_data() handled entirely at arch level and arches
> handing over the vdso data pointer to generic C VDSO functions all the
> time (as in my v2 series) ?
No. That's again moving the same code to all architectures.
> B/ Data pointer being handed over all the way up for arches wanting to
> do so, no changes at all for others (as in my v3 series) ?
Too much ifdeffery
> C/ __arch_get_vdso_data() being called at the outermost generic level
> for arches not interested in handling data pointer from the caller (as
> suggested by Thomas) ?
>
> Andy, with A/ you were concerned about arches being able to do PC
> related accesses. Would it be an issue for C/ as well ? If not, I guess
> C/ would be cleaner than B/ allthought not as clean as A which doesn't
> add any #ifdefery at all.
You can avoid ifdeffery with C if you do:
static __maybe_unused int
__cvdso_data_clock_gettime(clockid_t clock, struct __kernel_timespec *ts,
const struct vdso_data *vd)
{
.....
}
static __maybe_unused int
__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
{
const struct vdso_data *vd = __arch_get_vdso_data();
return __cvdso_data_clock_gettime(clock, ts, vd);
}
and then use __cvdso_data_clock_gettime on PPC and let the other archs
unmodified.
Thanks,
tglx
next prev parent reply other threads:[~2020-01-16 10:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 02/12] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 03/12] lib: vdso: mark __cvdso_clock_getres() as static Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 04/12] lib: vdso: inline do_hres() and do_coarse() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time Christophe Leroy
2020-01-14 11:31 ` Thomas Gleixner
2020-01-13 17:08 ` [RFC PATCH v3 07/12] powerpc/vdso: simplify __get_datapage() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
2020-01-14 23:06 ` Thomas Gleixner
2020-01-15 6:15 ` Christophe Leroy
2020-01-16 9:16 ` Christophe Leroy
2020-01-16 10:35 ` Thomas Gleixner [this message]
2020-01-16 20:22 ` Andy Lutomirski
2020-01-13 17:08 ` [RFC PATCH v3 09/12] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 11/12] lib: vdso: split clock verification out of __arch_get_hw_counter() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid() Christophe Leroy
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