From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24BC8E95A91 for ; Mon, 9 Oct 2023 13:27:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376769AbjJIN12 (ORCPT ); Mon, 9 Oct 2023 09:27:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376776AbjJIN11 (ORCPT ); Mon, 9 Oct 2023 09:27:27 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05F8D99 for ; Mon, 9 Oct 2023 06:27:26 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47572C433C8; Mon, 9 Oct 2023 13:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696858045; bh=tjJS2ZfdDm/fB4IKb+zcBU4XpxeoQ1HWKqnV5iqrr8Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QfNZeOHD5B8VNknGqqwCa4OwibWhbsxlU3aD8+OmykkH1pQNgp0hk0eMlqPWEA0Hh PAAnBi7c7M0TouN/V4FtRqiH2neqCRMc+ZM2DSoj7kL39EbhlVWQcC8N799iDioAh4 6eqsOLyRy/jpZKFZFvIgvcJzCGl9ThaVuHPGogHU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, John David Anglin , Helge Deller Subject: [PATCH 5.15 75/75] parisc: Restore __ldcw_align for PA-RISC 2.0 processors Date: Mon, 9 Oct 2023 15:02:37 +0200 Message-ID: <20231009130113.917593405@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231009130111.200710898@linuxfoundation.org> References: <20231009130111.200710898@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: John David Anglin commit 914988e099fc658436fbd7b8f240160c352b6552 upstream. Back in 2005, Kyle McMartin removed the 16-byte alignment for ldcw semaphores on PA 2.0 machines (CONFIG_PA20). This broke spinlocks on pre PA8800 processors. The main symptom was random faults in mmap'd memory (e.g., gcc compilations, etc). Unfortunately, the errata for this ldcw change is lost. The issue is the 16-byte alignment required for ldcw semaphore instructions can only be reduced to natural alignment when the ldcw operation can be handled coherently in cache. Only PA8800 and PA8900 processors actually support doing the operation in cache. Aligning the spinlock dynamically adds two integer instructions to each spinlock. Tested on rp3440, c8000 and a500. Signed-off-by: John David Anglin Link: https://lore.kernel.org/linux-parisc/6b332788-2227-127f-ba6d-55e99ecf4ed8@bell.net/T/#t Link: https://lore.kernel.org/linux-parisc/20050609050702.GB4641@roadwarrior.mcmartin.ca/ Cc: stable@vger.kernel.org Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- arch/parisc/include/asm/ldcw.h | 36 +++++++++++++++++-------------- arch/parisc/include/asm/spinlock_types.h | 5 ---- 2 files changed, 20 insertions(+), 21 deletions(-) --- a/arch/parisc/include/asm/ldcw.h +++ b/arch/parisc/include/asm/ldcw.h @@ -2,14 +2,28 @@ #ifndef __PARISC_LDCW_H #define __PARISC_LDCW_H -#ifndef CONFIG_PA20 /* Because kmalloc only guarantees 8-byte alignment for kmalloc'd data, and GCC only guarantees 8-byte alignment for stack locals, we can't be assured of 16-byte alignment for atomic lock data even if we specify "__attribute ((aligned(16)))" in the type declaration. So, we use a struct containing an array of four ints for the atomic lock type and dynamically select the 16-byte aligned int from the array - for the semaphore. */ + for the semaphore. */ + +/* From: "Jim Hull" + I've attached a summary of the change, but basically, for PA 2.0, as + long as the ",CO" (coherent operation) completer is implemented, then the + 16-byte alignment requirement for ldcw and ldcd is relaxed, and instead + they only require "natural" alignment (4-byte for ldcw, 8-byte for + ldcd). + + Although the cache control hint is accepted by all PA 2.0 processors, + it is only implemented on PA8800/PA8900 CPUs. Prior PA8X00 CPUs still + require 16-byte alignment. If the address is unaligned, the operation + of the instruction is undefined. The ldcw instruction does not generate + unaligned data reference traps so misaligned accesses are not detected. + This hid the problem for years. So, restore the 16-byte alignment dropped + by Kyle McMartin in "Remove __ldcw_align for PA-RISC 2.0 processors". */ #define __PA_LDCW_ALIGNMENT 16 #define __PA_LDCW_ALIGN_ORDER 4 @@ -19,22 +33,12 @@ & ~(__PA_LDCW_ALIGNMENT - 1); \ (volatile unsigned int *) __ret; \ }) -#define __LDCW "ldcw" -#else /*CONFIG_PA20*/ -/* From: "Jim Hull" - I've attached a summary of the change, but basically, for PA 2.0, as - long as the ",CO" (coherent operation) completer is specified, then the - 16-byte alignment requirement for ldcw and ldcd is relaxed, and instead - they only require "natural" alignment (4-byte for ldcw, 8-byte for - ldcd). */ - -#define __PA_LDCW_ALIGNMENT 4 -#define __PA_LDCW_ALIGN_ORDER 2 -#define __ldcw_align(a) (&(a)->slock) +#ifdef CONFIG_PA20 #define __LDCW "ldcw,co" - -#endif /*!CONFIG_PA20*/ +#else +#define __LDCW "ldcw" +#endif /* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. We don't explicitly expose that "*a" may be written as reload --- a/arch/parisc/include/asm/spinlock_types.h +++ b/arch/parisc/include/asm/spinlock_types.h @@ -3,13 +3,8 @@ #define __ASM_SPINLOCK_TYPES_H typedef struct { -#ifdef CONFIG_PA20 - volatile unsigned int slock; -# define __ARCH_SPIN_LOCK_UNLOCKED { 1 } -#else volatile unsigned int lock[4]; # define __ARCH_SPIN_LOCK_UNLOCKED { { 1, 1, 1, 1 } } -#endif } arch_spinlock_t;