From patchwork Sun Jul 12 14:24:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 40042 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 92EFB385703E; Sun, 12 Jul 2020 14:24:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 92EFB385703E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1594563894; bh=ocj5txl8L83yrbRLe+3B6YBrHnUYnbbib3aPnUQbINM=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=m/K2VhuDmk2lMZOT/ADyg0b1KuAhXCqF6Wch4C7f56Xs/dpBtHlccha6au4I+0ldw 0u8Mr1AM17gxU65xX3Vifjv3PnGOftoM7NL59cMZWeBBmWT2HC2r3OBNzkUB7jXeET c1JU2F4eCp2x9ht3cfE7X+HtBD7jOpLEW/9u2APQ= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by sourceware.org (Postfix) with ESMTPS id 2A4373857C61 for ; Sun, 12 Jul 2020 14:24:50 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 2A4373857C61 Received: by mail-pg1-x52e.google.com with SMTP id d4so4857646pgk.4 for ; Sun, 12 Jul 2020 07:24:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ocj5txl8L83yrbRLe+3B6YBrHnUYnbbib3aPnUQbINM=; b=Yxpy8Qy1ZGDqE5H9txoATnZ3fGBy1FDrOjmlqmdR327MZ0NWMbbu2ijzbNKFMt1o8E xWWGRJ97bvnpAaS7n1A3Rl14w8Gj61C/UeP9mHjzZeYaAk8RSYfxpp11SiJSifyNwIOu f/YIe0DcGjNxKLXS9K5K4tfqwLcjR9CYr7OZmQb5h9XDod99gLHQ7secdTYGx+5EpV71 T6wP2iJy2IYYWoJlAKiSxTrfO5Vwn8jadpXkwNd2cxrbkmOdLpz3lujr00WOMuMf6pAu EQzesIWVXGymJRU+wt5lFU17HQypZZ/3Vp1v0xCGuhC2YbqFNfYae4+hv2Tbptci1pPI wrfg== X-Gm-Message-State: AOAM532kAwGeu8TJ324mP8ECJtoT84uOa70qMWxXtnUeTOqvaSODj6ZF rNh1M9injPt60NOTIBLAkyMoJi2D0T4= X-Google-Smtp-Source: ABdhPJzH5Vlb8qGCXy0cdcGHPEI1Pw37PMilm8oeQth4Ec7+Od+UzcoT/h12bBs3r4FqQsX551t/Ow== X-Received: by 2002:aa7:948c:: with SMTP id z12mr39877011pfk.47.1594563889039; Sun, 12 Jul 2020 07:24:49 -0700 (PDT) Received: from gnu-cfl-2.localdomain (c-69-181-90-243.hsd1.ca.comcast.net. [69.181.90.243]) by smtp.gmail.com with ESMTPSA id l17sm10910225pgn.48.2020.07.12.07.24.47 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Jul 2020 07:24:47 -0700 (PDT) Received: from gnu-cfl-2.localdomain (localhost [IPv6:::1]) by gnu-cfl-2.localdomain (Postfix) with ESMTP id 6B1961A0246 for ; Sun, 12 Jul 2020 07:24:46 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH 1/3] x86: Initialize CPU info via IFUNC relocation [BZ 26203] Date: Sun, 12 Jul 2020 07:24:44 -0700 Message-Id: <20200712142446.2184885-2-hjl.tools@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200712142446.2184885-1-hjl.tools@gmail.com> References: <20200712142446.2184885-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-12.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" X86 CPU features in ld.so are initialized by init_cpu_features, which is invoked by DL_PLATFORM_INIT from _dl_sysdep_start. But when ld.so is loaded by static executable, DL_PLATFORM_INIT is never called. Also x86 cache info in libc.o and libc.a is initialized by a constructor which may be called too late. Instead, we should initialize x86 CPU features and cache info by initializing dummy function pointers via IFUNC relocation. Note: _dl_x86_init_cpu_features can be called more than once from DL_PLATFORM_INIT and during relocation. --- sysdeps/i386/dl-machine.h | 3 +-- sysdeps/x86/cacheinfo.c | 10 +++++++++- sysdeps/x86/dl-get-cpu-features.c | 23 ++++++++++++++++++++++- sysdeps/x86/include/cpu-features.h | 1 + sysdeps/x86_64/dl-machine.h | 3 +-- 5 files changed, 34 insertions(+), 6 deletions(-) diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h index 0f08079e48..5e22e795cc 100644 --- a/sysdeps/i386/dl-machine.h +++ b/sysdeps/i386/dl-machine.h @@ -25,7 +25,6 @@ #include #include #include -#include /* Return nonzero iff ELF header is compatible with the running host. */ static inline int __attribute__ ((unused)) @@ -250,7 +249,7 @@ dl_platform_init (void) #if IS_IN (rtld) /* init_cpu_features has been called early from __libc_start_main in static executable. */ - init_cpu_features (&GLRO(dl_x86_cpu_features)); + _dl_x86_init_cpu_features (); #else if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0') /* Avoid an empty string which would disturb us. */ diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c index 217c21c34f..7a325ab70e 100644 --- a/sysdeps/x86/cacheinfo.c +++ b/sysdeps/x86/cacheinfo.c @@ -756,7 +756,6 @@ intel_bug_no_cache_info: static void -__attribute__((constructor)) init_cacheinfo (void) { /* Find out what brand of processor. */ @@ -770,6 +769,8 @@ init_cacheinfo (void) unsigned int threads = 0; const struct cpu_features *cpu_features = __get_cpu_features (); + assert (cpu_features->basic.kind != arch_kind_unknown); + if (cpu_features->basic.kind == arch_kind_intel) { data = handle_intel (_SC_LEVEL1_DCACHE_SIZE, cpu_features); @@ -894,4 +895,11 @@ init_cacheinfo (void) # endif } +/* NB: Call init_cacheinfo by initializing a dummy function pointer via + IFUNC relocation. */ +extern void __x86_cacheinfo (void) attribute_hidden; +const void (*__x86_cacheinfo_p) (void) attribute_hidden + = __x86_cacheinfo; + +__ifunc (__x86_cacheinfo, __x86_cacheinfo, NULL, void, init_cacheinfo); #endif diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c index 5f9e46b0c6..592a6d5f6b 100644 --- a/sysdeps/x86/dl-get-cpu-features.c +++ b/sysdeps/x86/dl-get-cpu-features.c @@ -1,4 +1,4 @@ -/* This file is part of the GNU C Library. +/* Initialize CPU feature data via IFUNC relocation. Copyright (C) 2015-2020 Free Software Foundation, Inc. The GNU C Library is free software; you can redistribute it and/or @@ -18,6 +18,27 @@ #include +#ifdef SHARED +# include + +/* NB: Call init_cpu_features by initializing a dummy function pointer + via IFUNC relocation. */ +extern void __x86_cpu_features (void) attribute_hidden; +const void (*__x86_cpu_features_p) (void) attribute_hidden + = __x86_cpu_features; + +void +_dl_x86_init_cpu_features (void) +{ + struct cpu_features *cpu_features = __get_cpu_features (); + if (cpu_features->basic.kind == arch_kind_unknown) + init_cpu_features (cpu_features); +} + +__ifunc (__x86_cpu_features, __x86_cpu_features, NULL, void, + _dl_x86_init_cpu_features); +#endif + #undef __x86_get_cpu_features const struct cpu_features * diff --git a/sysdeps/x86/include/cpu-features.h b/sysdeps/x86/include/cpu-features.h index dcf29b6fe8..f62be0b9b3 100644 --- a/sysdeps/x86/include/cpu-features.h +++ b/sysdeps/x86/include/cpu-features.h @@ -159,6 +159,7 @@ struct cpu_features /* Unused for x86. */ # define INIT_ARCH() # define __x86_get_cpu_features(max) (&GLRO(dl_x86_cpu_features)) +extern void _dl_x86_init_cpu_features (void) attribute_hidden; # endif # ifdef __x86_64__ diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index ca73d8fef9..773e94c8bb 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -26,7 +26,6 @@ #include #include #include -#include /* Return nonzero iff ELF header is compatible with the running host. */ static inline int __attribute__ ((unused)) @@ -225,7 +224,7 @@ dl_platform_init (void) #if IS_IN (rtld) /* init_cpu_features has been called early from __libc_start_main in static executable. */ - init_cpu_features (&GLRO(dl_x86_cpu_features)); + _dl_x86_init_cpu_features (); #else if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0') /* Avoid an empty string which would disturb us. */