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Date: Thu, 02 Feb 2023 15:50:33 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: torvalds@...ux-foundation.org
Cc: corbet@....net, will@...nel.org, peterz@...radead.org,
boqun.feng@...il.com, mark.rutland@....com,
catalin.marinas@....com, dennis@...nel.org, tj@...nel.org,
cl@...ux.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
agordeev@...ux.ibm.com, borntraeger@...ux.ibm.com,
svens@...ux.ibm.com, tglx@...utronix.de, mingo@...hat.com,
bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
hpa@...or.com, joro@...tes.org, suravee.suthikulpanit@....com,
robin.murphy@....com, dwmw2@...radead.org,
baolu.lu@...ux.intel.com, Arnd Bergmann <arnd@...db.de>,
Herbert Xu <herbert@...dor.apana.org.au>, davem@...emloft.net,
penberg@...nel.org, rientjes@...gle.com, iamjoonsoo.kim@....com,
Andrew Morton <akpm@...ux-foundation.org>, vbabka@...e.cz,
roman.gushchin@...ux.dev, 42.hyeyoo@...il.com,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-s390@...r.kernel.org,
iommu@...ts.linux.dev, linux-arch@...r.kernel.org,
linux-crypto@...r.kernel.org
Subject: [PATCH v2 03/10] arch: Introduce arch_{,try_}_cmpxchg128{,_local}()
For all architectures that currently support cmpxchg_double()
implement the cmpxchg128() family of functions that is basically the
same but with a saner interface.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
arch/arm64/include/asm/atomic_ll_sc.h | 41 +++++++++++++++++++++++++
arch/arm64/include/asm/atomic_lse.h | 31 +++++++++++++++++++
arch/arm64/include/asm/cmpxchg.h | 26 ++++++++++++++++
arch/s390/include/asm/cmpxchg.h | 14 ++++++++
arch/x86/include/asm/cmpxchg_32.h | 3 +
arch/x86/include/asm/cmpxchg_64.h | 55 +++++++++++++++++++++++++++++++++-
6 files changed, 168 insertions(+), 2 deletions(-)
--- a/arch/arm64/include/asm/atomic_ll_sc.h
+++ b/arch/arm64/include/asm/atomic_ll_sc.h
@@ -326,6 +326,47 @@ __CMPXCHG_DBL( , , , )
__CMPXCHG_DBL(_mb, dmb ish, l, "memory")
#undef __CMPXCHG_DBL
+
+union __u128_halves {
+ u128 full;
+ struct {
+ u64 low, high;
+ };
+};
+
+#define __CMPXCHG128(name, mb, rel, cl...) \
+static __always_inline u128 \
+__ll_sc__cmpxchg128##name(volatile u128 *ptr, u128 old, u128 new) \
+{ \
+ union __u128_halves r, o = { .full = (old) }, \
+ n = { .full = (new) }; \
+ unsigned int tmp; \
+ \
+ asm volatile("// __cmpxchg128" #name "\n" \
+ " prfm pstl1strm, %[v]\n" \
+ "1: ldxp %[rl], %[rh], %[v]\n" \
+ " cmp %[rl], %[ol]\n" \
+ " ccmp %[rh], %[oh], 0, eq\n" \
+ " b.ne 2f\n" \
+ " st" #rel "xp %w[tmp], %[nl], %[nh], %[v]\n" \
+ " cbnz %w[tmp], 1b\n" \
+ " " #mb "\n" \
+ "2:" \
+ : [v] "+Q" (*(u128 *)ptr), \
+ [rl] "=&r" (r.low), [rh] "=&r" (r.high), \
+ [tmp] "=&r" (tmp) \
+ : [ol] "r" (o.low), [oh] "r" (o.high), \
+ [nl] "r" (n.low), [nh] "r" (n.high) \
+ : "cc", ##cl); \
+ \
+ return r.full; \
+}
+
+__CMPXCHG128( , , )
+__CMPXCHG128(_mb, dmb ish, l, "memory")
+
+#undef __CMPXCHG128
+
#undef K
#endif /* __ASM_ATOMIC_LL_SC_H */
--- a/arch/arm64/include/asm/atomic_lse.h
+++ b/arch/arm64/include/asm/atomic_lse.h
@@ -324,4 +324,35 @@ __CMPXCHG_DBL(_mb, al, "memory")
#undef __CMPXCHG_DBL
+#define __CMPXCHG128(name, mb, cl...) \
+static __always_inline u128 \
+__lse__cmpxchg128##name(volatile u128 *ptr, u128 old, u128 new) \
+{ \
+ union __u128_halves r, o = { .full = (old) }, \
+ n = { .full = (new) }; \
+ register unsigned long x0 asm ("x0") = o.low; \
+ register unsigned long x1 asm ("x1") = o.high; \
+ register unsigned long x2 asm ("x2") = n.low; \
+ register unsigned long x3 asm ("x3") = n.high; \
+ register unsigned long x4 asm ("x4") = (unsigned long)ptr; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " casp" #mb "\t%[old1], %[old2], %[new1], %[new2], %[v]\n"\
+ : [old1] "+&r" (x0), [old2] "+&r" (x1), \
+ [v] "+Q" (*(u128 *)ptr) \
+ : [new1] "r" (x2), [new2] "r" (x3), [ptr] "r" (x4), \
+ [oldval1] "r" (o.low), [oldval2] "r" (o.high) \
+ : cl); \
+ \
+ r.low = x0; r.high = x1; \
+ \
+ return r.full; \
+}
+
+__CMPXCHG128( , )
+__CMPXCHG128(_mb, al, "memory")
+
+#undef __CMPXCHG128
+
#endif /* __ASM_ATOMIC_LSE_H */
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -147,6 +147,19 @@ __CMPXCHG_DBL(_mb)
#undef __CMPXCHG_DBL
+#define __CMPXCHG128(name) \
+static inline u128 __cmpxchg128##name(volatile u128 *ptr, \
+ u128 old, u128 new) \
+{ \
+ return __lse_ll_sc_body(_cmpxchg128##name, \
+ ptr, old, new); \
+}
+
+__CMPXCHG128( )
+__CMPXCHG128(_mb)
+
+#undef __CMPXCHG128
+
#define __CMPXCHG_GEN(sfx) \
static __always_inline unsigned long __cmpxchg##sfx(volatile void *ptr, \
unsigned long old, \
@@ -229,6 +242,19 @@ __CMPXCHG_GEN(_mb)
__ret; \
})
+/* cmpxchg128 */
+#define system_has_cmpxchg128() 1
+
+#define arch_cmpxchg128(ptr, o, n) \
+({ \
+ __cmpxchg128_mb((ptr), (o), (n)); \
+})
+
+#define arch_cmpxchg128_local(ptr, o, n) \
+({ \
+ __cmpxchg128((ptr), (o), (n)); \
+})
+
#define __CMPWAIT_CASE(w, sfx, sz) \
static inline void __cmpwait_case_##sz(volatile void *ptr, \
unsigned long val) \
--- a/arch/s390/include/asm/cmpxchg.h
+++ b/arch/s390/include/asm/cmpxchg.h
@@ -201,4 +201,18 @@ static __always_inline int __cmpxchg_dou
(unsigned long)(n1), (unsigned long)(n2)); \
})
+#define system_has_cmpxchg128() 1
+
+static __always_inline u128 arch_cmpxchg128(volatile u128 *ptr, u128 old, u128 new)
+{
+ asm volatile(
+ " cdsg %[old],%[new],%[ptr]\n"
+ : [old] "+d" (old), [ptr] "+QS" (*ptr)
+ : [new] "d" (new)
+ : "memory", "cc");
+ return old;
+}
+
+#define arch_cmpxchg128 arch_cmpxchg128
+
#endif /* __ASM_CMPXCHG_H */
--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -103,6 +103,7 @@ static inline bool __try_cmpxchg64(volat
#endif
-#define system_has_cmpxchg_double() boot_cpu_has(X86_FEATURE_CX8)
+#define system_has_cmpxchg_double() boot_cpu_has(X86_FEATURE_CX8)
+#define system_has_cmpxchg64() boot_cpu_has(X86_FEATURE_CX8)
#endif /* _ASM_X86_CMPXCHG_32_H */
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -20,6 +20,59 @@
arch_try_cmpxchg((ptr), (po), (n)); \
})
-#define system_has_cmpxchg_double() boot_cpu_has(X86_FEATURE_CX16)
+union __u128_halves {
+ u128 full;
+ struct {
+ u64 low, high;
+ };
+};
+
+static __always_inline u128 arch_cmpxchg128(volatile u128 *ptr, u128 old, u128 new)
+{
+ union __u128_halves o = { .full = old, }, n = { .full = new, };
+
+ asm volatile(LOCK_PREFIX "cmpxchg16b %[ptr]"
+ : [ptr] "+m" (*ptr),
+ "+a" (o.low), "+d" (o.high)
+ : "b" (n.low), "c" (n.high)
+ : "memory");
+
+ return o.full;
+}
+
+static __always_inline u128 arch_cmpxchg128_local(volatile u128 *ptr, u128 old, u128 new)
+{
+ union __u128_halves o = { .full = old, }, n = { .full = new, };
+
+ asm volatile("cmpxchg16b %[ptr]"
+ : [ptr] "+m" (*ptr),
+ "+a" (o.low), "+d" (o.high)
+ : "b" (n.low), "c" (n.high)
+ : "memory");
+
+ return o.full;
+}
+
+static __always_inline bool arch_try_cmpxchg128(volatile u128 *ptr, u128 *old, u128 new)
+{
+ union __u128_halves o = { .full = *old, }, n = { .full = new, };
+ bool ret;
+
+ asm volatile(LOCK_PREFIX "cmpxchg16b %[ptr]"
+ CC_SET(e)
+ : CC_OUT(e) (ret),
+ [ptr] "+m" (*ptr),
+ "+a" (o.low), "+d" (o.high)
+ : "b" (n.low), "c" (n.high)
+ : "memory");
+
+ if (unlikely(!ret))
+ *old = o.full;
+
+ return likely(ret);
+}
+
+#define system_has_cmpxchg_double() boot_cpu_has(X86_FEATURE_CX16)
+#define system_has_cmpxchg128() boot_cpu_has(X86_FEATURE_CX16)
#endif /* _ASM_X86_CMPXCHG_64_H */
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