From: Helge Deller <deller@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>, Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
dennis@kernel.org, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux.com>,
Heiko Carstens <hca@linux.ibm.com>,
gor@linux.ibm.com, Alexander Gordeev <agordeev@linux.ibm.com>,
borntraeger@linux.ibm.com, Sven Schnelle <svens@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Joerg Roedel <joro@8bytes.org>,
suravee.suthikulpanit@amd.com,
Robin Murphy <robin.murphy@arm.com>,
David Woodhouse <dwmw2@infradead.org>,
Baolu Lu <baolu.lu@linux.intel.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S . Miller" <davem@davemloft.net>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Roman Gushchin <roman.gushchin@linux.dev>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-s390@vger.kernel.org,
iommu@lists.linux.dev, Linux-Arch <linux-arch@vger.kernel.org>,
linux-crypto@vger.kernel.org,
Stephen Rothwell <sfr@canb.auug.org.au>,
Michael Ellerman <mpe@ellerman.id.au>,
"James E . J . Bottomley" <James.Bottomley@hansenpartnership.com>,
linux-parisc@vger.kernel.org,
John David Anglin <dave.anglin@bell.net>,
Sam James <sam@gentoo.org>
Subject: Re: [PATCH v2 07/12] parisc/percpu: Work around the lack of __SIZEOF_INT128__
Date: Thu, 1 Jun 2023 12:32:38 +0200 [thread overview]
Message-ID: <14c50e58-fecc-e96a-ee73-39ef4e4617c7@gmx.de> (raw)
In-Reply-To: <20230601101409.GS4253@hirez.programming.kicks-ass.net>
On 6/1/23 12:14, Peter Zijlstra wrote:
> On Wed, May 31, 2023 at 04:21:22PM +0200, Arnd Bergmann wrote:
>
>> It would be nice to have the hack more localized to parisc
>> and guarded with a CONFIG_GCC_VERSION check so we can kill
>> it off in the future, once we drop either gcc-10 or parisc
>> support.
>
> I vote for dropping parisc -- it's the only 64bit arch that doesn't have
> sane atomics.
Of course I'm against dropping parisc.
> Anyway, the below seems to work -- build tested with GCC-10.1
I don't think we need to care about gcc-10 on parisc.
Debian and Gentoo are the only supported distributions, while Debian
requires gcc-12 to build > 6.x kernels, and I assume Gentoo uses at least
gcc-12 as well.
So raising the gcc limit for parisc only (at least temporarily for now)
should be fine and your workaround below wouldn't be necessary, right?
Helge
> ---
> Subject: parisc/percpu: Work around the lack of __SIZEOF_INT128__
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Tue May 30 22:27:40 CEST 2023
>
> HPPA64 is unique in not providing __SIZEOF_INT128__ across all
> supported compilers, specifically it only started doing this with
> GCC-11.
>
> Since the per-cpu ops are universally availably, and
> this_cpu_{,try_}cmpxchg128() is expected to be available on all 64bit
> architectures a wee bodge is in order.
>
> Sadly, while C reverts to memcpy() for assignment of POD types, it does
> not revert to memcmp() for for equality. Therefore frob that manually.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/parisc/include/asm/percpu.h | 77 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 77 insertions(+)
>
> --- /dev/null
> +++ b/arch/parisc/include/asm/percpu.h
> @@ -0,0 +1,77 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_PARISC_PERCPU_H
> +#define _ASM_PARISC_PERCPU_H
> +
> +#include <linux/types.h>
> +
> +#if defined(CONFIG_64BIT) && CONFIG_GCC_VERSION < 1100000
> +
> +/*
> + * GCC prior to 11 does not provide __SIZEOF_INT128__ on HPPA64
> + * as such we need to provide an alternative implementation of
> + * {raw,this}_cpu_{,try_}cmpxchg128().
> + *
> + * This obviously doesn't function as u128 should, but for the purpose
> + * of per-cpu cmpxchg128 it might just do.
> + */
> +typedef struct {
> + u64 a, b;
> +} u128 __attribute__((aligned(16)));
> +
> +#define raw_cpu_generic_try_cmpxchg_memcmp(pcp, ovalp, nval) \
> +({ \
> + typeof(pcp) *__p = raw_cpu_ptr(&(pcp)); \
> + typeof(pcp) __val = *__p, __old = *(ovalp); \
> + bool __ret; \
> + if (!__builtin_memcmp(&__val, &__old, sizeof(pcp))) { \
> + *__p = nval; \
> + __ret = true; \
> + } else { \
> + *(ovalp) = __val; \
> + __ret = false; \
> + } \
> + __ret; \
> +})
> +
> +#define raw_cpu_generic_cmpxchg_memcmp(pcp, oval, nval) \
> +({ \
> + typeof(pcp) __old = (oval); \
> + raw_cpu_generic_try_cmpxchg_memcpy(pcp, &__old, nval); \
> + __old; \
> +})
> +
> +#define raw_cpu_cmpxchg128(pcp, oval, nval) \
> + raw_cpu_generic_cmpxchg_memcmp(pcp, oval, nval)
> +#define raw_cpu_try_cmpxchg128(pcp, ovalp, nval) \
> + raw_cpu_generic_try_cmpxchg_memcmp(pcp, ovalp, nval)
> +
> +#define this_cpu_generic_try_cmpxchg_memcmp(pcp, ovalp, nval) \
> +({ \
> + bool __ret; \
> + unsigned long __flags; \
> + raw_local_irq_save(__flags); \
> + __ret = raw_cpu_generic_try_cmpxchg_memcmp(pcp, ovalp, nval); \
> + raw_local_irq_restore(__flags); \
> + __ret; \
> +})
> +
> +#define this_cpu_generic_cmpxchg_memcmp(pcp, oval, nval) \
> +({ \
> + typeof(pcp) __ret; \
> + unsigned long __flags; \
> + raw_local_irq_save(__flags); \
> + __ret = raw_cpu_generic_cmpxchg_memcmp(pcp, oval, nval); \
> + raw_local_irq_restore(__flags); \
> + __ret; \
> +})
> +
> +#define this_cpu_cmpxchg128(pcp, oval, nval) \
> + this_cpu_generic_cmpxchg_memcmp(pcp, oval, nval)
> +#define this_cpu_try_cmpxchg128(pcp, ovalp, nval) \
> + this_cpu_generic_try_cmpxchg_memcmp(pcp, ovalp, nval)
> +
> +#endif /* !__SIZEOF_INT128__ */
> +
> +#include <asm-generic/percpu.h>
> +
> +#endif /* _ASM_PARISC_PERCPU_H */
next prev parent reply other threads:[~2023-06-01 10:35 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-31 13:08 [PATCH 00/12] Introduce cmpxchg128() -- aka. the demise of cmpxchg_double() Peter Zijlstra
2023-05-31 13:08 ` [PATCH 01/12] cyrpto/b128ops: Remove struct u128 Peter Zijlstra
2023-05-31 13:08 ` [PATCH 02/12] types: Introduce [us]128 Peter Zijlstra
2023-05-31 13:08 ` [PATCH 03/12] arch: Introduce arch_{,try_}_cmpxchg128{,_local}() Peter Zijlstra
2023-05-31 13:08 ` [PATCH 04/12] instrumentation: Wire up cmpxchg128() Peter Zijlstra
2023-05-31 13:08 ` [PATCH 05/12] percpu: Add {raw,this}_cpu_try_cmpxchg() Peter Zijlstra
2023-06-09 16:10 ` [PATCH v2 5/12] " Konrad Dybcio
2023-06-09 16:13 ` Nathan Chancellor
2023-06-09 16:20 ` Konrad Dybcio
2023-05-31 13:08 ` [PATCH 06/12] percpu: Wire up cmpxchg128 Peter Zijlstra
2023-05-31 13:08 ` [PATCH 07/12] percpu: #ifndef __SIZEOF_INT128__ Peter Zijlstra
2023-05-31 14:21 ` Arnd Bergmann
2023-05-31 15:50 ` Peter Zijlstra
2023-06-01 10:14 ` [PATCH v2 07/12] parisc/percpu: Work around the lack of __SIZEOF_INT128__ Peter Zijlstra
2023-06-01 10:32 ` Helge Deller [this message]
2023-06-01 10:50 ` Peter Zijlstra
2023-06-01 21:08 ` Sam James
2023-06-01 13:29 ` Linus Torvalds
2023-06-01 17:38 ` Masahiro Yamada
2023-06-02 14:39 ` Peter Zijlstra
2023-06-02 14:50 ` Mark Rutland
2023-06-02 16:09 ` Linus Torvalds
2023-06-02 17:00 ` H. Peter Anvin
2023-06-02 19:10 ` Peter Zijlstra
2023-06-02 19:20 ` H. Peter Anvin
2023-06-02 19:40 ` Peter Zijlstra
2023-06-02 19:57 ` Linus Torvalds
2023-06-02 20:42 ` Helge Deller
2023-05-31 13:08 ` [PATCH 08/12] x86,amd_iommu: Replace cmpxchg_double() Peter Zijlstra
2023-05-31 13:08 ` [PATCH 09/12] x86,intel_iommu: " Peter Zijlstra
2023-05-31 13:08 ` [PATCH 10/12] slub: " Peter Zijlstra
2023-05-31 13:08 ` [PATCH 11/12] arch: Remove cmpxchg_double Peter Zijlstra
2023-05-31 13:08 ` [PATCH 12/12] s390/cpum_sf: Convert to cmpxchg128() Peter Zijlstra
2023-05-31 14:47 ` [PATCH 00/12] Introduce cmpxchg128() -- aka. the demise of cmpxchg_double() Mark Rutland
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=14c50e58-fecc-e96a-ee73-39ef4e4617c7@gmx.de \
--to=deller@gmx.de \
--cc=42.hyeyoo@gmail.com \
--cc=James.Bottomley@hansenpartnership.com \
--cc=agordeev@linux.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=baolu.lu@linux.intel.com \
--cc=boqun.feng@gmail.com \
--cc=borntraeger@linux.ibm.com \
--cc=bp@alien8.de \
--cc=catalin.marinas@arm.com \
--cc=cl@linux.com \
--cc=corbet@lwn.net \
--cc=dave.anglin@bell.net \
--cc=dave.hansen@linux.intel.com \
--cc=davem@davemloft.net \
--cc=dennis@kernel.org \
--cc=dwmw2@infradead.org \
--cc=gor@linux.ibm.com \
--cc=hca@linux.ibm.com \
--cc=herbert@gondor.apana.org.au \
--cc=hpa@zytor.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=iommu@lists.linux.dev \
--cc=joro@8bytes.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-parisc@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=mpe@ellerman.id.au \
--cc=penberg@kernel.org \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=robin.murphy@arm.com \
--cc=roman.gushchin@linux.dev \
--cc=sam@gentoo.org \
--cc=sfr@canb.auug.org.au \
--cc=suravee.suthikulpanit@amd.com \
--cc=svens@linux.ibm.com \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=vbabka@suse.cz \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).