From patchwork Sun Mar 19 15:10:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergey Bugaev X-Patchwork-Id: 66610 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 0A8C33947C3D for ; Sun, 19 Mar 2023 15:16:42 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0A8C33947C3D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1679239002; bh=lulHsK2vpaxjIqOHpBApkSHcTfiMkO/3EFWLP2d77ME=; h=To:Cc:Subject:Date:In-Reply-To:References:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=qyILWLlbHWMu8f+6SHeQKrwX3xFOlzdVmpmmdH5LRmLlx585i4QvG+A7KeoOdR0j/ dRaCM7WuppVuWPIVHQmDTby1G+8ghX/9KPmaHJObma96KDg+tw7Sxyr5GZSEncFJNb XCyAtOAaKmAZ9o+IyoRQ+A1BS617f0MmvJ/ty3iA= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-lf1-x12c.google.com (mail-lf1-x12c.google.com [IPv6:2a00:1450:4864:20::12c]) by sourceware.org (Postfix) with ESMTPS id 260AE3858032 for ; Sun, 19 Mar 2023 15:11:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 260AE3858032 Received: by mail-lf1-x12c.google.com with SMTP id b10so10841933lfb.9 for ; Sun, 19 Mar 2023 08:11:20 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679238679; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=lulHsK2vpaxjIqOHpBApkSHcTfiMkO/3EFWLP2d77ME=; b=A2VXykoXN+MDG0NFm8WAZEGY2/I/zbIv4y1s7nxWW7m5Y7++RQ6M7YvAiYuNQEmTrP DzKVYlicInFKFVHLzEW3aQz9obxbZf2xcQqi1rHUxWNt+FXo6xQd4Vy8BuB2OPAbMRMJ Tfa7MKd3ku7Tx65XdyjNknHs/XOLFpymIhPuaRHvzepQS/Q92jkBDC08NqySjV/3Fbwz rvDYMBYCY07bop0QV9q8M8pnfye5109pUliMI9sICwWxs96FwlYp3QzzwCUkh0zRc7oD l7URVn8NFyNYHzzPTk4avb06v+9qqaGgNurDFH9e1ioDBBMjZqWS3qdZ1MTpQEBbBxxQ DS2g== X-Gm-Message-State: AO0yUKUJx80kVE7SWSav4Cb55v19a6Hww3Vx56BROTwIioyLi1ujnlxk V4IJSdttyRKnw81AV+dQi7ibQ2veweanZQ== X-Google-Smtp-Source: AK7set91UV6YrgXVMTx6HgCb3kiU/AdWBQ3Uq4qvFBu6StbYXpvAWa3HtIwceC115Ta0dCLLFgvjcA== X-Received: by 2002:a19:7003:0:b0:4e8:a0a3:e242 with SMTP id h3-20020a197003000000b004e8a0a3e242mr3316325lfc.7.1679238679320; Sun, 19 Mar 2023 08:11:19 -0700 (PDT) Received: from surface-pro-6.. ([2a00:1370:818c:4a57:577a:76f4:df43:5e66]) by smtp.gmail.com with ESMTPSA id m19-20020ac24253000000b004e90dee5469sm1274089lfl.157.2023.03.19.08.11.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Mar 2023 08:11:19 -0700 (PDT) To: libc-alpha@sourceware.org, bug-hurd@gnu.org Cc: Samuel Thibault , Sergey Bugaev Subject: [RFC PATCH glibc 24/34] hurd: Only check for TLS initialization inside rtld or in static builds Date: Sun, 19 Mar 2023 18:10:07 +0300 Message-Id: <20230319151017.531737-25-bugaevc@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230319151017.531737-1-bugaevc@gmail.com> References: <20230319151017.531737-1-bugaevc@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-10.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, URIBL_BLACK 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: Sergey Bugaev via Libc-alpha From: Sergey Bugaev Reply-To: Sergey Bugaev Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" When glibc is built as a shared library, TLS is always initialized by the call of TLS_INIT_TP () macro made inside the dynamic loader, prior to running the main program (see dl-call_tls_init_tp.h). We can take advantage of this: we know for sure that __LIBC_NO_TLS () will evaluate to 0 in all other cases, so let the compiler know that explicitly too. Also, only define _hurd_tls_init () and TLS_INIT_TP () under the same conditions (either !SHARED or inside rtld), to statically assert that this is the case. Other than a microoptimization, this also helps with avoiding awkward sharing of the __libc_tls_initialized variable between ld.so and libc.so that we would have to do otherwise -- we know for sure that no sharing is required, simply because __libc_tls_initialized would always be set to true inside libc.so. Signed-off-by: Sergey Bugaev --- sysdeps/mach/hurd/Makefile | 4 ++ sysdeps/mach/hurd/i386/dl-tls-initialized.c | 21 +++++++++ sysdeps/mach/hurd/i386/tls.h | 43 +++++++++++-------- sysdeps/mach/hurd/x86/init-first.c | 11 +---- sysdeps/mach/hurd/x86_64/dl-tls-initialized.c | 21 +++++++++ sysdeps/mach/hurd/x86_64/tls.h | 19 +++++--- 6 files changed, 85 insertions(+), 34 deletions(-) create mode 100644 sysdeps/mach/hurd/i386/dl-tls-initialized.c create mode 100644 sysdeps/mach/hurd/x86_64/dl-tls-initialized.c diff --git a/sysdeps/mach/hurd/Makefile b/sysdeps/mach/hurd/Makefile index d5584930..f43e92ba 100644 --- a/sysdeps/mach/hurd/Makefile +++ b/sysdeps/mach/hurd/Makefile @@ -197,6 +197,10 @@ ifeq (hurd, $(subdir)) sysdep_routines += cthreads endif +ifeq (elf, $(subdir)) +sysdep-dl-routines += dl-tls-initialized +endif + ifeq (io, $(subdir)) sysdep_routines += f_setlk close_nocancel close_nocancel_nostatus \ fcntl_nocancel open_nocancel openat_nocancel read_nocancel \ diff --git a/sysdeps/mach/hurd/i386/dl-tls-initialized.c b/sysdeps/mach/hurd/i386/dl-tls-initialized.c new file mode 100644 index 00000000..493ec239 --- /dev/null +++ b/sysdeps/mach/hurd/i386/dl-tls-initialized.c @@ -0,0 +1,21 @@ +/* Determine whether TLS is initialized, for i386/Hurd. + Copyright (C) 1995-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef SHARED +unsigned short __init1_desc; +#endif diff --git a/sysdeps/mach/hurd/i386/tls.h b/sysdeps/mach/hurd/i386/tls.h index 0f8dd241..ee7b8004 100644 --- a/sysdeps/mach/hurd/i386/tls.h +++ b/sysdeps/mach/hurd/i386/tls.h @@ -69,18 +69,6 @@ _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30, | (desc->high_word & 0xff000000)); \ }) -/* Return 1 if TLS is not initialized yet. */ -#ifndef SHARED -extern unsigned short __init1_desc; -#define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds) || (gs) == __init1_desc) -#else -#define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds)) -#endif - -#define __LIBC_NO_TLS() \ - ({ unsigned short ds, gs; \ - asm ("movw %%ds,%w0; movw %%gs,%w1" : "=q" (ds), "=q" (gs)); \ - __builtin_expect(__HURD_DESC_INITIAL(gs, ds), 0); }) #endif /* The TCB can have any size and the memory following the address the @@ -125,6 +113,28 @@ extern unsigned short __init1_desc; # define HURD_SEL_LDT(sel) (__builtin_expect ((sel) & 4, 0)) +#ifndef SHARED +extern unsigned short __init1_desc; +# define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds) || (gs) == __init1_desc) +#else +# define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds)) +#endif + +#if !defined (SHARED) || IS_IN (rtld) +/* Return 1 if TLS is not initialized yet. */ +extern inline bool __attribute__ ((unused)) +__LIBC_NO_TLS (void) +{ + unsigned short ds, gs; + asm ("movw %%ds, %w0\n" + "movw %%gs, %w1" + : "=q" (ds), "=q" (gs)); + return __glibc_unlikely (__HURD_DESC_INITIAL (gs, ds)); +} + +/* Code to initially initialize the thread pointer. This might need + special attention since 'errno' is not yet available and if the + operation can cause a failure 'errno' must not be touched. */ static inline bool __attribute__ ((unused)) _hurd_tls_init (tcbhead_t *tcb) { @@ -168,11 +178,10 @@ out: return success; } -/* Code to initially initialize the thread pointer. This might need - special attention since 'errno' is not yet available and if the - operation can cause a failure 'errno' must not be touched. */ -# define TLS_INIT_TP(descr) \ - _hurd_tls_init ((tcbhead_t *) (descr)) +# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr)) +#else /* defined (SHARED) && !IS_IN (rtld) */ +# define __LIBC_NO_TLS() 0 +#endif # if __GNUC_PREREQ (6, 0) diff --git a/sysdeps/mach/hurd/x86/init-first.c b/sysdeps/mach/hurd/x86/init-first.c index 48c330ec..89a5f44c 100644 --- a/sysdeps/mach/hurd/x86/init-first.c +++ b/sysdeps/mach/hurd/x86/init-first.c @@ -40,13 +40,6 @@ extern char **_dl_argv; #ifndef SHARED static tcbhead_t __init1_tcbhead; -# ifndef __x86_64__ -unsigned short __init1_desc; -# endif -#endif - -#ifdef __x86_64__ -unsigned char __libc_tls_initialized; #endif /* Things that want to be run before _hurd_init or much anything else. @@ -166,9 +159,7 @@ first_init (void) _hurd_tls_init (&__init1_tcbhead); /* Make sure __LIBC_NO_TLS () keeps evaluating to 1. */ -# ifdef __x86_64__ - __libc_tls_initialized = 0; -# else +# ifndef __x86_64__ asm ("movw %%gs,%w0" : "=m" (__init1_desc)); # endif #endif diff --git a/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c b/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c new file mode 100644 index 00000000..d0766f95 --- /dev/null +++ b/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c @@ -0,0 +1,21 @@ +/* Determine whether TLS is initialized, for x86_64/Hurd. + Copyright (C) 1995-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#if !defined (SHARED) || IS_IN (rtld) +unsigned short __libc_tls_initialized; +#endif diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h index cf74e1f4..da504d9c 100644 --- a/sysdeps/mach/hurd/x86_64/tls.h +++ b/sysdeps/mach/hurd/x86_64/tls.h @@ -68,10 +68,6 @@ _Static_assert (offsetof (tcbhead_t, stack_guard) == 0x28, _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70, "split stack pointer offset"); -extern unsigned char __libc_tls_initialized; - -# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0) - /* The TCB can have any size and the memory following the address the thread pointer points to is unspecified. Allocate the TCB there. */ # define TLS_TCB_AT_TP 1 @@ -87,8 +83,6 @@ extern unsigned char __libc_tls_initialized; # define TCB_ALIGNMENT 64 -# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr)) - # define THREAD_SELF \ (*(tcbhead_t * __seg_fs *) offsetof (tcbhead_t, tcb)) /* Read member of the thread descriptor directly. */ @@ -174,6 +168,10 @@ _hurd_tls_new (thread_t child, tcbhead_t *tcb) i386_FSGS_BASE_STATE_COUNT); } +# if !defined (SHARED) || IS_IN (rtld) +extern unsigned char __libc_tls_initialized; +# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0) + static inline bool __attribute__ ((unused)) _hurd_tls_init (tcbhead_t *tcb) { @@ -184,11 +182,18 @@ _hurd_tls_init (tcbhead_t *tcb) tcb->multiple_threads = 1; err = _hurd_tls_new (self, tcb); + if (err == 0) + __libc_tls_initialized = 1; __mach_port_deallocate (__mach_task_self (), self); - __libc_tls_initialized = 1; return err == 0; } +# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr)) +# else /* defined (SHARED) && !IS_IN (rtld) */ +# define __LIBC_NO_TLS() 0 +# endif + + /* Global scope switch support. */ # define THREAD_GSCOPE_FLAG_UNUSED 0