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[23.128.96.18]) by mx.google.com with ESMTP id t9si7854646plg.155.2021.10.26.06.04.44; Tue, 26 Oct 2021 06:05:01 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=sVr8uHtf; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235150AbhJZKJQ (ORCPT + 99 others); Tue, 26 Oct 2021 06:09:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:37026 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235127AbhJZKJP (ORCPT ); Tue, 26 Oct 2021 06:09:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B044F60551; Tue, 26 Oct 2021 10:06:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635242811; bh=/UUpq5yAb9SBJHAGQCwpJ++n+NDCz5SrvkBmQT9f4AM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sVr8uHtfZkNoSIOweaf+O71sFcTtweajZ2yUFEf0k7tTjrr/XnVapzQyhBdTESzpg dPlvZc6JfwlKPbQXRd+uOCce6LL9gAIs8QxdoqD4Dn+io4ZGXXvdBFqV6zDh8+zBIR ILQRg1UQm/8LEOGrruqpzcP8OFu3/sGB8yYXUE34H+v4wT9+UAQ/17/wMB7D7WFIEy RRZDoLcuf5Iw81u3vEqrdA4oStOQLyhAkBAc/esruUB/Buq2VZopf6Yt35koDGwauh LiS/nwKElHYcRW9EzmEyRizGSIShUFMtef8WWGoMXTurXqgHUmo0Y2oI5cTPtLY1+/ xQy68IqXxEPlA== From: Arnd Bergmann To: Peter Zijlstra , Thomas Gleixner , Ingo Molnar Cc: Arnd Bergmann , Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Guo Ren , Geert Uytterhoeven , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Alexander Gordeev , Yoshinori Sato , Rich Felker , Jeff Dike , Richard Weinberger , Anton Ivanov , Chris Zankel , Max Filippov , Darren Hart , Davidlohr Bueso , =?UTF-8?q?Andr=C3=A9=20Almeida?= , Andrew Morton , Mike Rapoport , Mark Rutland , Anshuman Khandual , linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org Subject: [PATCH 2/2] futex: remove futex_cmpxchg detection Date: Tue, 26 Oct 2021 12:03:48 +0200 Message-Id: <20211026100432.1730393-2-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20211026100432.1730393-1-arnd@kernel.org> References: <20211026100432.1730393-1-arnd@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann Now that all architectures have a working futex implementation in any configuration, remove the runtime detection code. Signed-off-by: Arnd Bergmann --- arch/arc/Kconfig | 1 - arch/arm/Kconfig | 1 - arch/arm64/Kconfig | 1 - arch/csky/Kconfig | 1 - arch/m68k/Kconfig | 1 - arch/riscv/Kconfig | 1 - arch/s390/Kconfig | 1 - arch/sh/Kconfig | 1 - arch/um/Kconfig | 1 - arch/um/kernel/skas/uaccess.c | 1 - arch/xtensa/Kconfig | 1 - init/Kconfig | 8 -------- kernel/futex/core.c | 35 ----------------------------------- kernel/futex/futex.h | 6 ------ kernel/futex/syscalls.c | 22 ---------------------- 15 files changed, 82 deletions(-) diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index 248389278e8f..f9413041686f 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -31,7 +31,6 @@ config ARC select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARC_MMU_V4 select HAVE_DEBUG_STACKOVERFLOW select HAVE_DEBUG_KMEMLEAK - select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_IOREMAP_PROT select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZMA diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index bb5d2c45477b..6448d311635d 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -93,7 +93,6 @@ config ARM select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !(THUMB2_KERNEL && CC_IS_CLANG) - select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7) select HAVE_IRQ_TIME_ACCOUNTING diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 0efc501f77aa..6c3c2ff5cef8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -193,7 +193,6 @@ config ARM64 select HAVE_PERF_USER_STACK_DUMP select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_FUNCTION_ARG_ACCESS_API - select HAVE_FUTEX_CMPXCHG if FUTEX select MMU_GATHER_RCU_TABLE_FREE select HAVE_RSEQ select HAVE_STACKPROTECTOR diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig index 823d3d5a9e11..efd7c5feac8b 100644 --- a/arch/csky/Kconfig +++ b/arch/csky/Kconfig @@ -53,7 +53,6 @@ config CSKY select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_ERROR_INJECTION - select HAVE_FUTEX_CMPXCHG if FUTEX && SMP select HAVE_FTRACE_MCOUNT_RECORD select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZO diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index 0b50da08a9c5..15a793c5b2dc 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -20,7 +20,6 @@ config M68K select HAVE_ASM_MODVERSIONS select HAVE_DEBUG_BUGVERBOSE select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED - select HAVE_FUTEX_CMPXCHG if MMU && FUTEX select HAVE_MOD_ARCH_SPECIFIC select HAVE_UID16 select MMU_GATHER_NO_RANGE if MMU diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 77a088d0a7e9..037fea9fac14 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -84,7 +84,6 @@ config RISCV select HAVE_DMA_CONTIGUOUS if MMU select HAVE_EBPF_JIT if MMU select HAVE_FUNCTION_ERROR_INJECTION - select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS select HAVE_GENERIC_VDSO if MMU && 64BIT select HAVE_IRQ_TIME_ACCOUNTING diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index f615c3f65f5a..1c9ecf619e04 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -164,7 +164,6 @@ config S390 select HAVE_FUNCTION_ERROR_INJECTION select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER - select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS select HAVE_GENERIC_VDSO select HAVE_IOREMAP_PROT if PCI diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index 6904f4bdbf00..93195d3368c0 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -34,7 +34,6 @@ config SUPERH select HAVE_FAST_GUP if MMU select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER - select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_FTRACE_MCOUNT_RECORD select HAVE_HW_BREAKPOINT select HAVE_IOREMAP_PROT if MMU && !X2TLB diff --git a/arch/um/Kconfig b/arch/um/Kconfig index c18b45f75d41..c906250d4970 100644 --- a/arch/um/Kconfig +++ b/arch/um/Kconfig @@ -14,7 +14,6 @@ config UML select HAVE_ARCH_SECCOMP_FILTER select HAVE_ASM_MODVERSIONS select HAVE_UID16 - select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_BUGVERBOSE select NO_DMA if !UML_DMA_EMULATION diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c index a509be911026..9e37a7c05990 100644 --- a/arch/um/kernel/skas/uaccess.c +++ b/arch/um/kernel/skas/uaccess.c @@ -348,7 +348,6 @@ EXPORT_SYMBOL(arch_futex_atomic_op_inuser); * 0 - On success * -EFAULT - User access resulted in a page fault * -EAGAIN - Atomic operation was unable to complete due to contention - * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG) */ int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index 0e56bad058fa..8ac599aa6d99 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -31,7 +31,6 @@ config XTENSA select HAVE_DMA_CONTIGUOUS select HAVE_EXIT_THREAD select HAVE_FUNCTION_TRACER - select HAVE_FUTEX_CMPXCHG if !MMU && FUTEX select HAVE_HW_BREAKPOINT if PERF_EVENTS select HAVE_IRQ_TIME_ACCOUNTING select HAVE_PCI diff --git a/init/Kconfig b/init/Kconfig index c0f55ea5a71f..538688598f2f 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1597,14 +1597,6 @@ config FUTEX_PI depends on FUTEX && RT_MUTEXES default y -config HAVE_FUTEX_CMPXCHG - bool - depends on FUTEX - help - Architectures should select this if futex_atomic_cmpxchg_inatomic() - is implemented and always working. This removes a couple of runtime - checks. - config EPOLL bool "Enable eventpoll support" if EXPERT default y diff --git a/kernel/futex/core.c b/kernel/futex/core.c index 25d8a88b32e5..926c2bb752bc 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -41,11 +41,6 @@ #include "futex.h" #include "../locking/rtmutex_common.h" -#ifndef CONFIG_HAVE_FUTEX_CMPXCHG -int __read_mostly futex_cmpxchg_enabled; -#endif - - /* * The base of the bucket array and its size are always used together * (after initialization only in futex_hash()), so ensure that they @@ -776,9 +771,6 @@ static void exit_robust_list(struct task_struct *curr) unsigned long futex_offset; int rc; - if (!futex_cmpxchg_enabled) - return; - /* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): @@ -874,9 +866,6 @@ static void compat_exit_robust_list(struct task_struct *curr) compat_long_t futex_offset; int rc; - if (!futex_cmpxchg_enabled) - return; - /* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): @@ -950,8 +939,6 @@ static void exit_pi_state_list(struct task_struct *curr) struct futex_hash_bucket *hb; union futex_key key = FUTEX_KEY_INIT; - if (!futex_cmpxchg_enabled) - return; /* * We are a ZOMBIE and nobody can enqueue itself on * pi_state_list anymore, but we have to be careful @@ -1125,26 +1112,6 @@ void futex_exit_release(struct task_struct *tsk) futex_cleanup_end(tsk, FUTEX_STATE_DEAD); } -static void __init futex_detect_cmpxchg(void) -{ -#ifndef CONFIG_HAVE_FUTEX_CMPXCHG - u32 curval; - - /* - * This will fail and we want it. Some arch implementations do - * runtime detection of the futex_atomic_cmpxchg_inatomic() - * functionality. We want to know that before we call in any - * of the complex code paths. Also we want to prevent - * registration of robust lists in that case. NULL is - * guaranteed to fault and we get -EFAULT on functional - * implementation, the non-functional ones will return - * -ENOSYS. - */ - if (futex_cmpxchg_value_locked(&curval, NULL, 0, 0) == -EFAULT) - futex_cmpxchg_enabled = 1; -#endif -} - static int __init futex_init(void) { unsigned int futex_shift; @@ -1163,8 +1130,6 @@ static int __init futex_init(void) futex_hashsize, futex_hashsize); futex_hashsize = 1UL << futex_shift; - futex_detect_cmpxchg(); - for (i = 0; i < futex_hashsize; i++) { atomic_set(&futex_queues[i].waiters, 0); plist_head_init(&futex_queues[i].chain); diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index 040ae4277cb0..c264cbeab71c 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -27,12 +27,6 @@ #define FLAGS_CLOCKRT 0x02 #define FLAGS_HAS_TIMEOUT 0x04 -#ifdef CONFIG_HAVE_FUTEX_CMPXCHG -#define futex_cmpxchg_enabled 1 -#else -extern int __read_mostly futex_cmpxchg_enabled; -#endif - #ifdef CONFIG_FAIL_FUTEX extern bool should_fail_futex(bool fshared); #else diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 6f91a07a6a83..086a22d1adb7 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -29,8 +29,6 @@ SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, size_t, len) { - if (!futex_cmpxchg_enabled) - return -ENOSYS; /* * The kernel knows only one size for now: */ @@ -56,9 +54,6 @@ SYSCALL_DEFINE3(get_robust_list, int, pid, unsigned long ret; struct task_struct *p; - if (!futex_cmpxchg_enabled) - return -ENOSYS; - rcu_read_lock(); ret = -ESRCH; @@ -103,17 +98,6 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, return -ENOSYS; } - switch (cmd) { - case FUTEX_LOCK_PI: - case FUTEX_LOCK_PI2: - case FUTEX_UNLOCK_PI: - case FUTEX_TRYLOCK_PI: - case FUTEX_WAIT_REQUEUE_PI: - case FUTEX_CMP_REQUEUE_PI: - if (!futex_cmpxchg_enabled) - return -ENOSYS; - } - switch (cmd) { case FUTEX_WAIT: val3 = FUTEX_BITSET_MATCH_ANY; @@ -323,9 +307,6 @@ COMPAT_SYSCALL_DEFINE2(set_robust_list, struct compat_robust_list_head __user *, head, compat_size_t, len) { - if (!futex_cmpxchg_enabled) - return -ENOSYS; - if (unlikely(len != sizeof(*head))) return -EINVAL; @@ -342,9 +323,6 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, unsigned long ret; struct task_struct *p; - if (!futex_cmpxchg_enabled) - return -ENOSYS; - rcu_read_lock(); ret = -ESRCH; -- 2.29.2