From patchwork Thu May 2 21:01:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13652070 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 799EA1E86E; Thu, 2 May 2024 21:01:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714683693; cv=none; b=MxE6ll2VwjRLsLCWMdR/idlT4yzK3FWNdiX9ohTl1bN7n6elEUqJlOSNgG7LIQhDOwhVu8iGNHtxdOtunH8rbhTrfFRQU+Q6nAlRg3+X0u99Av3KAwGGg7HXRRB0PNsb9fEJ17HUY9t3r3J0XmZXTrfmJD+njCBnHlFiF8YPEaY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714683693; c=relaxed/simple; bh=DR3v+TCvUQP4e/ehxPG1TPShLSicc1MnBYRHVivADlI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PJgV6ykfcRSpUbIDzE2/c7UMGFjMBg0Eth1I5wUHfdB/0GhsJEsrfUuUNRaz9PhYW5M5W6rgFS2RKdVInuro+CGjkZjzx0NRVHsgF7dygFIXeKEpeqrsICBfD1mEFwSsJBIMl9zos6/vbYNoQZx+lZBXpcV4haP1hXnwHrM9JR4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=jjZmo+ud; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="jjZmo+ud" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6Tj6ZIpwTpxFP5n0tD6RjyI7GGUAgGJQ848QLqTpZPQ=; b=jjZmo+udMjYSMMPEgqX5kknDfa 47sYQJmK8Soh7uEI7euzVF9SYAXxb0YHU4eiIKg9o0QjRYqPDRqHcr6ju1DM9moTUuhZCosfh6UHk MjYNEOLRqMTtJ4P5HqkduSuR8gesiBoFKROMPC3su97+l9zfOXrAwvxHWJYvEt4g6Wx02MoL8xtt5 003kDCAKxI7fPI9OThaWKodHDeEwtQXRT3WA5ILtariaDXvyQ4gViJ2azsIN2kQjtRZW588MEBdQs ev8B0m08KwgqUquaasV+V2ftL3guQwSxHHfPhQvH2Cl5Ny0UZK6vPhMYvp9wt8Cdpa2Gqa0aob67/ 8iXDfGaw==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1s2dYQ-009kWR-2y; Thu, 02 May 2024 21:01:23 +0000 Date: Thu, 2 May 2024 22:01:22 +0100 From: Al Viro To: "Paul E. McKenney" Cc: John Paul Adrian Glaubitz , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, elver@google.com, akpm@linux-foundation.org, tglx@linutronix.de, peterz@infradead.org, dianders@chromium.org, pmladek@suse.com, arnd@arndb.de, torvalds@linux-foundation.org, kernel-team@meta.com, Andi Shyti , Palmer Dabbelt , Masami Hiramatsu , linux-sh@vger.kernel.org, linux-alpha@vger.kernel.org Subject: alpha cmpxchg.h (was Re: [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg) Message-ID: <20240502210122.GA2322432@ZenIV> References: <20240501230130.1111603-12-paulmck@kernel.org> <1376850f47279e3a3f4f40e3de2784ae3ac30414.camel@physik.fu-berlin.de> <6f7743601fe7bd50c2855a8fd1ed8f766ef03cac.camel@physik.fu-berlin.de> <9a4e1928-961d-43af-9951-71786b97062a@paulmck-laptop> <20240502205345.GK2118490@ZenIV> Precedence: bulk X-Mailing-List: linux-sh@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240502205345.GK2118490@ZenIV> Sender: Al Viro On Thu, May 02, 2024 at 09:53:45PM +0100, Al Viro wrote: > What's more, load-locked/store-conditional doesn't have 16bit and 8bit > variants on any Alphas - it's always 32bit (ldl_l) or 64bit (ldq_l). > > What BWX adds is load/store byte/word, load/store byte/word unaligned > and sign-extend byte/word. IOW, it's absolutely irrelevant for > cmpxchg (or xchg) purposes. FWIW, I do have a cmpxchg-related patch for alpha - the mess with xchg.h (parametrized double include) is no longer needed, and hadn't been since 2018 (fbfcd0199170 "locking/xchg/alpha: Remove superfluous memory barriers from the _local() variants" was the point when the things settled down). Only tangentially related to your stuff, but it makes the damn thing easier to follow. commit e992b5436ccd504b07a390118cf2be686355b957 Author: Al Viro Date: Mon Apr 8 17:43:37 2024 -0400 alpha: no need to include asm/xchg.h twice We used to generate different helpers for local and full {cmp,}xchg(); these days the barriers are in arch_{cmp,}xchg() instead and generated helpers are identical for local and full cases. No need for those parametrized includes of asm/xchg.h - we might as well insert its contents directly in asm/cmpxchg.h and do it only once. Signed-off-by: Al Viro diff --git a/arch/alpha/include/asm/cmpxchg.h b/arch/alpha/include/asm/cmpxchg.h index 91d4a4d9258c..ae1b96479d0c 100644 --- a/arch/alpha/include/asm/cmpxchg.h +++ b/arch/alpha/include/asm/cmpxchg.h @@ -3,17 +3,232 @@ #define _ALPHA_CMPXCHG_H /* - * Atomic exchange routines. + * Atomic exchange. + * Since it can be used to implement critical sections + * it must clobber "memory" (also for interrupts in UP). */ -#define ____xchg(type, args...) __arch_xchg ## type ## _local(args) -#define ____cmpxchg(type, args...) __cmpxchg ## type ## _local(args) -#include +static inline unsigned long +____xchg_u8(volatile char *m, unsigned long val) +{ + unsigned long ret, tmp, addr64; + + __asm__ __volatile__( + " andnot %4,7,%3\n" + " insbl %1,%4,%1\n" + "1: ldq_l %2,0(%3)\n" + " extbl %2,%4,%0\n" + " mskbl %2,%4,%2\n" + " or %1,%2,%2\n" + " stq_c %2,0(%3)\n" + " beq %2,2f\n" + ".subsection 2\n" + "2: br 1b\n" + ".previous" + : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64) + : "r" ((long)m), "1" (val) : "memory"); + + return ret; +} + +static inline unsigned long +____xchg_u16(volatile short *m, unsigned long val) +{ + unsigned long ret, tmp, addr64; + + __asm__ __volatile__( + " andnot %4,7,%3\n" + " inswl %1,%4,%1\n" + "1: ldq_l %2,0(%3)\n" + " extwl %2,%4,%0\n" + " mskwl %2,%4,%2\n" + " or %1,%2,%2\n" + " stq_c %2,0(%3)\n" + " beq %2,2f\n" + ".subsection 2\n" + "2: br 1b\n" + ".previous" + : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64) + : "r" ((long)m), "1" (val) : "memory"); + + return ret; +} + +static inline unsigned long +____xchg_u32(volatile int *m, unsigned long val) +{ + unsigned long dummy; + + __asm__ __volatile__( + "1: ldl_l %0,%4\n" + " bis $31,%3,%1\n" + " stl_c %1,%2\n" + " beq %1,2f\n" + ".subsection 2\n" + "2: br 1b\n" + ".previous" + : "=&r" (val), "=&r" (dummy), "=m" (*m) + : "rI" (val), "m" (*m) : "memory"); + + return val; +} + +static inline unsigned long +____xchg_u64(volatile long *m, unsigned long val) +{ + unsigned long dummy; + + __asm__ __volatile__( + "1: ldq_l %0,%4\n" + " bis $31,%3,%1\n" + " stq_c %1,%2\n" + " beq %1,2f\n" + ".subsection 2\n" + "2: br 1b\n" + ".previous" + : "=&r" (val), "=&r" (dummy), "=m" (*m) + : "rI" (val), "m" (*m) : "memory"); + + return val; +} + +/* This function doesn't exist, so you'll get a linker error + if something tries to do an invalid xchg(). */ +extern void __xchg_called_with_bad_pointer(void); + +static __always_inline unsigned long +____xchg(volatile void *ptr, unsigned long x, int size) +{ + return + size == 1 ? ____xchg_u8(ptr, x) : + size == 2 ? ____xchg_u16(ptr, x) : + size == 4 ? ____xchg_u32(ptr, x) : + size == 8 ? ____xchg_u64(ptr, x) : + (__xchg_called_with_bad_pointer(), x); +} + +/* + * Atomic compare and exchange. Compare OLD with MEM, if identical, + * store NEW in MEM. Return the initial value in MEM. Success is + * indicated by comparing RETURN with OLD. + */ + +static inline unsigned long +____cmpxchg_u8(volatile char *m, unsigned char old, unsigned char new) +{ + unsigned long prev, tmp, cmp, addr64; + + __asm__ __volatile__( + " andnot %5,7,%4\n" + " insbl %1,%5,%1\n" + "1: ldq_l %2,0(%4)\n" + " extbl %2,%5,%0\n" + " cmpeq %0,%6,%3\n" + " beq %3,2f\n" + " mskbl %2,%5,%2\n" + " or %1,%2,%2\n" + " stq_c %2,0(%4)\n" + " beq %2,3f\n" + "2:\n" + ".subsection 2\n" + "3: br 1b\n" + ".previous" + : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64) + : "r" ((long)m), "Ir" (old), "1" (new) : "memory"); + + return prev; +} + +static inline unsigned long +____cmpxchg_u16(volatile short *m, unsigned short old, unsigned short new) +{ + unsigned long prev, tmp, cmp, addr64; + + __asm__ __volatile__( + " andnot %5,7,%4\n" + " inswl %1,%5,%1\n" + "1: ldq_l %2,0(%4)\n" + " extwl %2,%5,%0\n" + " cmpeq %0,%6,%3\n" + " beq %3,2f\n" + " mskwl %2,%5,%2\n" + " or %1,%2,%2\n" + " stq_c %2,0(%4)\n" + " beq %2,3f\n" + "2:\n" + ".subsection 2\n" + "3: br 1b\n" + ".previous" + : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64) + : "r" ((long)m), "Ir" (old), "1" (new) : "memory"); + + return prev; +} + +static inline unsigned long +____cmpxchg_u32(volatile int *m, int old, int new) +{ + unsigned long prev, cmp; + + __asm__ __volatile__( + "1: ldl_l %0,%5\n" + " cmpeq %0,%3,%1\n" + " beq %1,2f\n" + " mov %4,%1\n" + " stl_c %1,%2\n" + " beq %1,3f\n" + "2:\n" + ".subsection 2\n" + "3: br 1b\n" + ".previous" + : "=&r"(prev), "=&r"(cmp), "=m"(*m) + : "r"((long) old), "r"(new), "m"(*m) : "memory"); + + return prev; +} + +static inline unsigned long +____cmpxchg_u64(volatile long *m, unsigned long old, unsigned long new) +{ + unsigned long prev, cmp; + + __asm__ __volatile__( + "1: ldq_l %0,%5\n" + " cmpeq %0,%3,%1\n" + " beq %1,2f\n" + " mov %4,%1\n" + " stq_c %1,%2\n" + " beq %1,3f\n" + "2:\n" + ".subsection 2\n" + "3: br 1b\n" + ".previous" + : "=&r"(prev), "=&r"(cmp), "=m"(*m) + : "r"((long) old), "r"(new), "m"(*m) : "memory"); + + return prev; +} + +/* This function doesn't exist, so you'll get a linker error + if something tries to do an invalid cmpxchg(). */ +extern void __cmpxchg_called_with_bad_pointer(void); + +static __always_inline unsigned long +____cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, + int size) +{ + return + size == 1 ? ____cmpxchg_u8(ptr, old, new) : + size == 2 ? ____cmpxchg_u16(ptr, old, new) : + size == 4 ? ____cmpxchg_u32(ptr, old, new) : + size == 8 ? ____cmpxchg_u64(ptr, old, new) : + (__cmpxchg_called_with_bad_pointer(), old); +} #define xchg_local(ptr, x) \ ({ \ __typeof__(*(ptr)) _x_ = (x); \ - (__typeof__(*(ptr))) __arch_xchg_local((ptr), (unsigned long)_x_,\ + (__typeof__(*(ptr))) ____xchg((ptr), (unsigned long)_x_, \ sizeof(*(ptr))); \ }) @@ -21,7 +236,7 @@ ({ \ __typeof__(*(ptr)) _o_ = (o); \ __typeof__(*(ptr)) _n_ = (n); \ - (__typeof__(*(ptr))) __cmpxchg_local((ptr), (unsigned long)_o_, \ + (__typeof__(*(ptr))) ____cmpxchg((ptr), (unsigned long)_o_, \ (unsigned long)_n_, \ sizeof(*(ptr))); \ }) @@ -32,12 +247,6 @@ cmpxchg_local((ptr), (o), (n)); \ }) -#undef ____xchg -#undef ____cmpxchg -#define ____xchg(type, args...) __arch_xchg ##type(args) -#define ____cmpxchg(type, args...) __cmpxchg ##type(args) -#include - /* * The leading and the trailing memory barriers guarantee that these * operations are fully ordered. @@ -48,7 +257,7 @@ __typeof__(*(ptr)) _x_ = (x); \ smp_mb(); \ __ret = (__typeof__(*(ptr))) \ - __arch_xchg((ptr), (unsigned long)_x_, sizeof(*(ptr))); \ + ____xchg((ptr), (unsigned long)_x_, sizeof(*(ptr))); \ smp_mb(); \ __ret; \ }) @@ -59,7 +268,7 @@ __typeof__(*(ptr)) _o_ = (o); \ __typeof__(*(ptr)) _n_ = (n); \ smp_mb(); \ - __ret = (__typeof__(*(ptr))) __cmpxchg((ptr), \ + __ret = (__typeof__(*(ptr))) ____cmpxchg((ptr), \ (unsigned long)_o_, (unsigned long)_n_, sizeof(*(ptr)));\ smp_mb(); \ __ret; \ @@ -71,6 +280,4 @@ arch_cmpxchg((ptr), (o), (n)); \ }) -#undef ____cmpxchg - #endif /* _ALPHA_CMPXCHG_H */ diff --git a/arch/alpha/include/asm/xchg.h b/arch/alpha/include/asm/xchg.h deleted file mode 100644 index 7adb80c6746a..000000000000 --- a/arch/alpha/include/asm/xchg.h +++ /dev/null @@ -1,246 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _ALPHA_CMPXCHG_H -#error Do not include xchg.h directly! -#else -/* - * xchg/xchg_local and cmpxchg/cmpxchg_local share the same code - * except that local version do not have the expensive memory barrier. - * So this file is included twice from asm/cmpxchg.h. - */ - -/* - * Atomic exchange. - * Since it can be used to implement critical sections - * it must clobber "memory" (also for interrupts in UP). - */ - -static inline unsigned long -____xchg(_u8, volatile char *m, unsigned long val) -{ - unsigned long ret, tmp, addr64; - - __asm__ __volatile__( - " andnot %4,7,%3\n" - " insbl %1,%4,%1\n" - "1: ldq_l %2,0(%3)\n" - " extbl %2,%4,%0\n" - " mskbl %2,%4,%2\n" - " or %1,%2,%2\n" - " stq_c %2,0(%3)\n" - " beq %2,2f\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64) - : "r" ((long)m), "1" (val) : "memory"); - - return ret; -} - -static inline unsigned long -____xchg(_u16, volatile short *m, unsigned long val) -{ - unsigned long ret, tmp, addr64; - - __asm__ __volatile__( - " andnot %4,7,%3\n" - " inswl %1,%4,%1\n" - "1: ldq_l %2,0(%3)\n" - " extwl %2,%4,%0\n" - " mskwl %2,%4,%2\n" - " or %1,%2,%2\n" - " stq_c %2,0(%3)\n" - " beq %2,2f\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64) - : "r" ((long)m), "1" (val) : "memory"); - - return ret; -} - -static inline unsigned long -____xchg(_u32, volatile int *m, unsigned long val) -{ - unsigned long dummy; - - __asm__ __volatile__( - "1: ldl_l %0,%4\n" - " bis $31,%3,%1\n" - " stl_c %1,%2\n" - " beq %1,2f\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - : "=&r" (val), "=&r" (dummy), "=m" (*m) - : "rI" (val), "m" (*m) : "memory"); - - return val; -} - -static inline unsigned long -____xchg(_u64, volatile long *m, unsigned long val) -{ - unsigned long dummy; - - __asm__ __volatile__( - "1: ldq_l %0,%4\n" - " bis $31,%3,%1\n" - " stq_c %1,%2\n" - " beq %1,2f\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - : "=&r" (val), "=&r" (dummy), "=m" (*m) - : "rI" (val), "m" (*m) : "memory"); - - return val; -} - -/* This function doesn't exist, so you'll get a linker error - if something tries to do an invalid xchg(). */ -extern void __xchg_called_with_bad_pointer(void); - -static __always_inline unsigned long -____xchg(, volatile void *ptr, unsigned long x, int size) -{ - switch (size) { - case 1: - return ____xchg(_u8, ptr, x); - case 2: - return ____xchg(_u16, ptr, x); - case 4: - return ____xchg(_u32, ptr, x); - case 8: - return ____xchg(_u64, ptr, x); - } - __xchg_called_with_bad_pointer(); - return x; -} - -/* - * Atomic compare and exchange. Compare OLD with MEM, if identical, - * store NEW in MEM. Return the initial value in MEM. Success is - * indicated by comparing RETURN with OLD. - */ - -static inline unsigned long -____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new) -{ - unsigned long prev, tmp, cmp, addr64; - - __asm__ __volatile__( - " andnot %5,7,%4\n" - " insbl %1,%5,%1\n" - "1: ldq_l %2,0(%4)\n" - " extbl %2,%5,%0\n" - " cmpeq %0,%6,%3\n" - " beq %3,2f\n" - " mskbl %2,%5,%2\n" - " or %1,%2,%2\n" - " stq_c %2,0(%4)\n" - " beq %2,3f\n" - "2:\n" - ".subsection 2\n" - "3: br 1b\n" - ".previous" - : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64) - : "r" ((long)m), "Ir" (old), "1" (new) : "memory"); - - return prev; -} - -static inline unsigned long -____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new) -{ - unsigned long prev, tmp, cmp, addr64; - - __asm__ __volatile__( - " andnot %5,7,%4\n" - " inswl %1,%5,%1\n" - "1: ldq_l %2,0(%4)\n" - " extwl %2,%5,%0\n" - " cmpeq %0,%6,%3\n" - " beq %3,2f\n" - " mskwl %2,%5,%2\n" - " or %1,%2,%2\n" - " stq_c %2,0(%4)\n" - " beq %2,3f\n" - "2:\n" - ".subsection 2\n" - "3: br 1b\n" - ".previous" - : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64) - : "r" ((long)m), "Ir" (old), "1" (new) : "memory"); - - return prev; -} - -static inline unsigned long -____cmpxchg(_u32, volatile int *m, int old, int new) -{ - unsigned long prev, cmp; - - __asm__ __volatile__( - "1: ldl_l %0,%5\n" - " cmpeq %0,%3,%1\n" - " beq %1,2f\n" - " mov %4,%1\n" - " stl_c %1,%2\n" - " beq %1,3f\n" - "2:\n" - ".subsection 2\n" - "3: br 1b\n" - ".previous" - : "=&r"(prev), "=&r"(cmp), "=m"(*m) - : "r"((long) old), "r"(new), "m"(*m) : "memory"); - - return prev; -} - -static inline unsigned long -____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new) -{ - unsigned long prev, cmp; - - __asm__ __volatile__( - "1: ldq_l %0,%5\n" - " cmpeq %0,%3,%1\n" - " beq %1,2f\n" - " mov %4,%1\n" - " stq_c %1,%2\n" - " beq %1,3f\n" - "2:\n" - ".subsection 2\n" - "3: br 1b\n" - ".previous" - : "=&r"(prev), "=&r"(cmp), "=m"(*m) - : "r"((long) old), "r"(new), "m"(*m) : "memory"); - - return prev; -} - -/* This function doesn't exist, so you'll get a linker error - if something tries to do an invalid cmpxchg(). */ -extern void __cmpxchg_called_with_bad_pointer(void); - -static __always_inline unsigned long -____cmpxchg(, volatile void *ptr, unsigned long old, unsigned long new, - int size) -{ - switch (size) { - case 1: - return ____cmpxchg(_u8, ptr, old, new); - case 2: - return ____cmpxchg(_u16, ptr, old, new); - case 4: - return ____cmpxchg(_u32, ptr, old, new); - case 8: - return ____cmpxchg(_u64, ptr, old, new); - } - __cmpxchg_called_with_bad_pointer(); - return old; -} - -#endif