From: Peter Zijlstra <peterz@infradead.org>
To: 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>,
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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>,
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Hyeonggon Yoo <42.hyeyoo@gmail.com>,
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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>,
Helge Deller <deller@gmx.de>,
linux-parisc@vger.kernel.org
Subject: [PATCH v2 07/12] parisc/percpu: Work around the lack of __SIZEOF_INT128__
Date: Thu, 1 Jun 2023 12:14:09 +0200 [thread overview]
Message-ID: <20230601101409.GS4253@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <70a69deb-7ad4-45b2-8e13-34955594a7ce@app.fastmail.com>
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.
Anyway, the below seems to work -- build tested with GCC-10.1
---
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 10:15 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 ` Peter Zijlstra [this message]
2023-06-01 10:32 ` [PATCH v2 07/12] parisc/percpu: Work around the lack of __SIZEOF_INT128__ Helge Deller
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
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