From patchwork Wed Feb 15 12:43:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 65042 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 118753858430 for ; Wed, 15 Feb 2023 12:44:28 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 118753858430 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1676465068; bh=WvJG2HVpbhr/KNDI78Z0rrcnHPB29H90UADXXenZFK0=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=fexHl2l+fLNKaaKrH6GMJ4nctuqUczWVN9ttDcMEEk51VU85jQ3RrHZVC52DXv8Hy UKD4fUSELEesfkDn5+O8MY/dsKQmq469Pvij2+Hn6TjzLlmBTQszty/l4DG9GkyGyx kFGF5Bonruu+SEtZod22ize0wwqZbJMMz6p69nXc= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-oa1-x2a.google.com (mail-oa1-x2a.google.com [IPv6:2001:4860:4864:20::2a]) by sourceware.org (Postfix) with ESMTPS id 18E8938582B7 for ; Wed, 15 Feb 2023 12:44:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 18E8938582B7 Received: by mail-oa1-x2a.google.com with SMTP id 586e51a60fabf-16dcb07b805so16188571fac.0 for ; Wed, 15 Feb 2023 04:44:02 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=WvJG2HVpbhr/KNDI78Z0rrcnHPB29H90UADXXenZFK0=; b=N74JpvdOmr1YrkL+9n7lb1uP8qRgfo5Qj4ENK1U4wSbPbJizp0871W3l7kAtNJngkO lWmrHAq/GritrtL0Yg+14up6aZDloEFfsj/F16wrWG/Da2/gdAsc/6gD6CEZYqpJxEkz 3KZTbSm1caoJc9FiSJAiAhYfX0uwaezt6P+3IgVEdlKWSiDtFSLqkjdAhJiVfSUe2s8E ERiXlIm1JDLfOGdCnRSvvaS7xmPG5bzvgB3P5V3fLSL6ywG2XObSiVd6B8I/9M2qwMp3 2xRFZ1nBEHn3ce+EtItTVbaTm15DiyddpY/bcCx+WBf/9c8XopTemLvVPe6RE/FHkKUm W5jQ== X-Gm-Message-State: AO0yUKV2EOr9go4pNIeUhELIJCrx8CWzYg8C2e5I+HVaki6jMV5PFEkk 2Ygz/Uil7QAero3dbkKRnI5tIP6FQmKmBjeq2rQ= X-Google-Smtp-Source: AK7set9+hUs/FhOxyRmR8TYEjv7vTQvJIdmimcjMSt711+Qpb+raNOetuYYyy5FiJbDe9s7QNAwTAA== X-Received: by 2002:a05:6870:f14b:b0:16a:be46:cc30 with SMTP id l11-20020a056870f14b00b0016abe46cc30mr1029054oac.50.1676465039142; Wed, 15 Feb 2023 04:43:59 -0800 (PST) Received: from mandiga.. ([2804:1b3:a7c3:3a5:152:b181:8086:4b67]) by smtp.gmail.com with ESMTPSA id e187-20020a4a55c4000000b0051a72e69e24sm6600107oob.37.2023.02.15.04.43.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Feb 2023 04:43:58 -0800 (PST) To: libc-alpha@sourceware.org, Florian Weimer Subject: [PATCH] i386: Use pthread_barrier for synchronization on tst-bz21269 Date: Wed, 15 Feb 2023 09:43:54 -0300 Message-Id: <20230215124354.2069895-1-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-12.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_NUMSUBJECT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Netto Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" To improve the false negative in patchwork buildbot. Checked on i686-linux-gnu. --- sysdeps/unix/sysv/linux/i386/tst-bz21269.c | 58 +++++++--------------- 1 file changed, 17 insertions(+), 41 deletions(-) diff --git a/sysdeps/unix/sysv/linux/i386/tst-bz21269.c b/sysdeps/unix/sysv/linux/i386/tst-bz21269.c index 1850240c34..07880650c6 100644 --- a/sysdeps/unix/sysv/linux/i386/tst-bz21269.c +++ b/sysdeps/unix/sysv/linux/i386/tst-bz21269.c @@ -20,16 +20,13 @@ more specifically in do_multicpu_tests function. The main changes are: - - C11 atomics instead of plain access. + - Use pthread_barrier instead of atomic and futexes. - Remove x86_64 support which simplifies the syscall handling and fallbacks. - Replicate only the test required to trigger the issue for the BZ#21269. */ -#include - #include -#include #include #include @@ -40,6 +37,7 @@ #include #include #include +#include static int xset_thread_area (struct user_desc *u_info) @@ -55,13 +53,6 @@ xmodify_ldt (int func, const void *ptr, unsigned long bytecount) TEST_VERIFY_EXIT (syscall (SYS_modify_ldt, 1, ptr, bytecount) == 0); } -static int -futex (int *uaddr, int futex_op, int val, void *timeout, int *uaddr2, - int val3) -{ - return syscall (SYS_futex, uaddr, futex_op, val, timeout, uaddr2, val3); -} - static void xsethandler (int sig, void (*handler)(int, siginfo_t *, void *), int flags) { @@ -69,7 +60,7 @@ xsethandler (int sig, void (*handler)(int, siginfo_t *, void *), int flags) sa.sa_sigaction = handler; sa.sa_flags = SA_SIGINFO | flags; TEST_VERIFY_EXIT (sigemptyset (&sa.sa_mask) == 0); - TEST_VERIFY_EXIT (sigaction (sig, &sa, 0) == 0); + xsigaction (sig, &sa, 0); } static jmp_buf jmpbuf; @@ -123,33 +114,24 @@ setup_low_user_desc (void) low_user_desc_clear->seg_not_present = 1; } -/* Possible values of futex: - 0: thread is idle. - 1: thread armed. - 2: thread should clear LDT entry 0. - 3: thread should exit. */ -static atomic_uint ftx; +static pthread_barrier_t barrier; static void * threadproc (void *ctx) { - while (1) + for (int i = 0; i < 5; i++) { - futex ((int *) &ftx, FUTEX_WAIT, 1, NULL, NULL, 0); - while (atomic_load (&ftx) != 2) - { - if (atomic_load (&ftx) >= 3) - return NULL; - } + xpthread_barrier_wait (&barrier); /* clear LDT entry 0. */ const struct user_desc desc = { 0 }; xmodify_ldt (1, &desc, sizeof (desc)); - /* If ftx == 2, set it to zero, If ftx == 100, quit. */ - if (atomic_fetch_add (&ftx, -2) != 2) - return NULL; + /* Wait for 'ss' set in main thread. */ + xpthread_barrier_wait (&barrier); } + + return NULL; } @@ -180,6 +162,8 @@ do_test (void) /* Some kernels send SIGBUS instead. */ xsethandler (SIGBUS, sigsegv_handler, 0); + xpthread_barrier_init (&barrier, NULL, 2); + thread = xpthread_create (0, threadproc, 0); asm volatile ("mov %%ss, %0" : "=rm" (orig_ss)); @@ -190,8 +174,7 @@ do_test (void) continue; /* Make sure the thread is ready after the last test. */ - while (atomic_load (&ftx) != 0) - ; + xpthread_barrier_wait (&barrier); struct user_desc desc = { .entry_number = 0, @@ -207,28 +190,21 @@ do_test (void) xmodify_ldt (0x11, &desc, sizeof (desc)); - /* Arm the thread. */ - ftx = 1; - futex ((int*) &ftx, FUTEX_WAKE, 0, NULL, NULL, 0); + xpthread_barrier_wait (&barrier); asm volatile ("mov %0, %%ss" : : "r" (0x7)); - /* Fire up thread modify_ldt call. */ - atomic_store (&ftx, 2); - - while (atomic_load (&ftx) != 0) - ; + xpthread_barrier_wait (&barrier); /* On success, modify_ldt will segfault us synchronously and we will escape via siglongjmp. */ support_record_failure (); } - atomic_store (&ftx, 100); - futex ((int*) &ftx, FUTEX_WAKE, 0, NULL, NULL, 0); - xpthread_join (thread); + xpthread_barrier_destroy (&barrier); + return 0; }