From patchwork Thu Oct 10 15:14:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Matthias_M=C3=A4nnich?= X-Patchwork-Id: 11183803 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 088811864 for ; Thu, 10 Oct 2019 15:16:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2AF02190F for ; Thu, 10 Oct 2019 15:16:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tyB4NIF4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726633AbfJJPQP (ORCPT ); Thu, 10 Oct 2019 11:16:15 -0400 Received: from mail-wm1-f74.google.com ([209.85.128.74]:39560 "EHLO mail-wm1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726597AbfJJPQO (ORCPT ); Thu, 10 Oct 2019 11:16:14 -0400 Received: by mail-wm1-f74.google.com with SMTP id 190so2761186wme.4 for ; Thu, 10 Oct 2019 08:16:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=i3Erxj68tMcwkIZ2NUT8ZG/xvUxR9gGY2fME2mvG5JY=; b=tyB4NIF4cyHaIp1deXiILh3c/NzNlyLfId7Y01hj7cBrdXiAD5xlGQJutMNAGCtNmG ZKUSPPCStZWLOV/zrn9ZVfQ0dgRnycAO478qTG/1k2UWvgsEZWhqRUE1IWFVAwnLdUMr N/5Y1aBXECx5kPn+1WmAsLLyI8fXweizVUDikwqGEMRkPfDLOpCUyQv5GgqrPQBUQi2s MAxDgN89vvewQZl4gT7NCY39rc4pVbYCKMGlL1U4iX9rbcA4FP8tw7l01GYvjrCqShoc /STRfyXIDPQXEuI1ky55ZGGvrHCrNZVlQ4bPrfRsNptOT/sHAQAxJA5mUdJGineCrdTT Pw+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=i3Erxj68tMcwkIZ2NUT8ZG/xvUxR9gGY2fME2mvG5JY=; b=jb6qusAOc4OpUMrqcB1UT0PB1VJVZEMImsE4it9jCCCtbedC5hg6r7l7JKdG97FU3L pePkWQSGtmFU1GdluKmzzjvY6DEx5vjz1V0QoiEqNM/MA6lWdW8IAlkuCTgb/R2bP+f3 fetU6blI10jomVODDJp1OAx3wK361W4u8RLppmWPQGfjREOVhvdKO9nyx6QXCN7lvfxe 67Lx/cT9giWqSLcEqBklmRVnHv2eqRUGIGwIYZEdCHBct1tzy+AvoWEYN5RODCNWHBOk xqBqOV1BctsJ3zr3zOBqLfmM06rFlF6aG7rTQeQgnosMcOb1NV91sls1u6OomsARSvXg lFrg== X-Gm-Message-State: APjAAAX5sWam3EKz/2F6jEe439CvasNePUDYtUsTHmH6XztFQ9CgX7S2 OLnVoHC9HnNJQlt9CSbTbWJpPCYlIDR/RA== X-Google-Smtp-Source: APXvYqzykiWp/pYZwS7FjqEfOT321sqVXUyjY6mctjsFEEZhtdsbXpRqa/2zu/NB+vr22KsSqa76pviTrglD3w== X-Received: by 2002:a5d:4691:: with SMTP id u17mr8903588wrq.41.1570720571422; Thu, 10 Oct 2019 08:16:11 -0700 (PDT) Date: Thu, 10 Oct 2019 16:14:43 +0100 In-Reply-To: <20191010151443.7399-1-maennich@google.com> Message-Id: <20191010151443.7399-5-maennich@google.com> Mime-Version: 1.0 References: <20191010151443.7399-1-maennich@google.com> X-Mailer: git-send-email 2.23.0.581.g78d2f28ef7-goog Subject: [PATCH 4/4] export: avoid code duplication in include/linux/export.h From: Matthias Maennich To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, maennich@google.com, Jessica Yu , Masahiro Yamada , Martijn Coenen , Lucas De Marchi , Shaun Ruffell , Greg Kroah-Hartman , Will Deacon , linux-kbuild@vger.kernel.org, linux-modules@vger.kernel.org Sender: owner-linux-modules@vger.kernel.org Precedence: bulk List-ID: Now that the namespace value is not part of the __ksymtab entry name anymore, we can simplify the implementation of EXPORT_SYMBOL*. By allowing the empty string "" to represent 'no namespace', we can unify the implementation and drop a lot redundant code. That increases readability and maintainability. As Masahiro pointed out earlier, "The drawback of this change is, it grows the code size. When the symbol has no namespace, sym->namespace was previously NULL, but it is now am empty string "". So, it increases 1 byte for every no namespace EXPORT_SYMBOL. A typical kernel configuration has 10K exported symbols, so it increases 10KB in rough estimation." Suggested-by: Masahiro Yamada Signed-off-by: Matthias Maennich Reviewed-by: Greg Kroah-Hartman Reviewed-by: Masahiro Yamada --- include/linux/export.h | 92 +++++++++++++----------------------------- kernel/module.c | 2 +- 2 files changed, 29 insertions(+), 65 deletions(-) diff --git a/include/linux/export.h b/include/linux/export.h index f24b86d7dd4d..201262793369 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -46,7 +46,7 @@ extern struct module __this_module; * absolute relocations that require runtime processing on relocatable * kernels. */ -#define __KSYMTAB_ENTRY_NS(sym, sec) \ +#define __KSYMTAB_ENTRY(sym, sec) \ __ADDRESSABLE(sym) \ asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ " .balign 4 \n" \ @@ -56,34 +56,17 @@ extern struct module __this_module; " .long __kstrtabns_" #sym "- . \n" \ " .previous \n") -#define __KSYMTAB_ENTRY(sym, sec) \ - __ADDRESSABLE(sym) \ - asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ - " .balign 4 \n" \ - "__ksymtab_" #sym ": \n" \ - " .long " #sym "- . \n" \ - " .long __kstrtab_" #sym "- . \n" \ - " .long 0 \n" \ - " .previous \n") - struct kernel_symbol { int value_offset; int name_offset; int namespace_offset; }; #else -#define __KSYMTAB_ENTRY_NS(sym, sec) \ - static const struct kernel_symbol __ksymtab_##sym \ - __attribute__((section("___ksymtab" sec "+" #sym), used)) \ - __aligned(sizeof(void *)) \ - = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } - #define __KSYMTAB_ENTRY(sym, sec) \ static const struct kernel_symbol __ksymtab_##sym \ - asm("__ksymtab_" #sym) \ __attribute__((section("___ksymtab" sec "+" #sym), used)) \ __aligned(sizeof(void *)) \ - = { (unsigned long)&sym, __kstrtab_##sym, NULL } + = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } struct kernel_symbol { unsigned long value; @@ -94,28 +77,20 @@ struct kernel_symbol { #ifdef __GENKSYMS__ -#define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym) -#define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym) +#define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) #else -#define ___export_symbol_common(sym, sec) \ +/* For every exported symbol, place a struct in the __ksymtab section */ +#define ___EXPORT_SYMBOL(sym, sec, ns) \ extern typeof(sym) sym; \ __CRC_SYMBOL(sym, sec); \ static const char __kstrtab_##sym[] \ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ - = #sym \ - -/* For every exported symbol, place a struct in the __ksymtab section */ -#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ - ___export_symbol_common(sym, sec); \ + = #sym; \ static const char __kstrtabns_##sym[] \ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ - = #ns; \ - __KSYMTAB_ENTRY_NS(sym, sec) - -#define ___EXPORT_SYMBOL(sym, sec) \ - ___export_symbol_common(sym, sec); \ + = ns; \ __KSYMTAB_ENTRY(sym, sec) #endif @@ -127,8 +102,7 @@ struct kernel_symbol { * be reused in other execution contexts such as the UEFI stub or the * decompressor. */ -#define __EXPORT_SYMBOL_NS(sym, sec, ns) -#define __EXPORT_SYMBOL(sym, sec) +#define __EXPORT_SYMBOL(sym, sec, ns) #elif defined(CONFIG_TRIM_UNUSED_KSYMS) @@ -144,48 +118,38 @@ struct kernel_symbol { #define __ksym_marker(sym) \ static int __ksym_marker_##sym[0] __section(".discard.ksym") __used -#define __EXPORT_SYMBOL(sym, sec) \ - __ksym_marker(sym); \ - __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) -#define __cond_export_sym(sym, sec, conf) \ - ___cond_export_sym(sym, sec, conf) -#define ___cond_export_sym(sym, sec, enabled) \ - __cond_export_sym_##enabled(sym, sec) -#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) -#define __cond_export_sym_0(sym, sec) /* nothing */ - -#define __EXPORT_SYMBOL_NS(sym, sec, ns) \ +#define __EXPORT_SYMBOL(sym, sec, ns) \ __ksym_marker(sym); \ - __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) -#define __cond_export_ns_sym(sym, sec, ns, conf) \ - ___cond_export_ns_sym(sym, sec, ns, conf) -#define ___cond_export_ns_sym(sym, sec, ns, enabled) \ - __cond_export_ns_sym_##enabled(sym, sec, ns) -#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) -#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ + __cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) +#define __cond_export_sym(sym, sec, ns, conf) \ + ___cond_export_sym(sym, sec, ns, conf) +#define ___cond_export_sym(sym, sec, ns, enabled) \ + __cond_export_sym_##enabled(sym, sec, ns) +#define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) +#define __cond_export_sym_0(sym, sec, ns) /* nothing */ #else -#define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns) -#define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec) +#define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) #endif /* CONFIG_MODULES */ #ifdef DEFAULT_SYMBOL_NAMESPACE -#undef __EXPORT_SYMBOL -#define __EXPORT_SYMBOL(sym, sec) \ - __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE) +#include +#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE)) +#else +#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "") #endif -#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") -#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") -#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") -#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) -#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) +#define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "") +#define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl") +#define EXPORT_SYMBOL_GPL_FUTURE(sym) _EXPORT_SYMBOL(sym, "_gpl_future") +#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", #ns) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", #ns) #ifdef CONFIG_UNUSED_SYMBOLS -#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") -#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") +#define EXPORT_UNUSED_SYMBOL(sym) _EXPORT_SYMBOL(sym, "_unused") +#define EXPORT_UNUSED_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_unused_gpl") #else #define EXPORT_UNUSED_SYMBOL(sym) #define EXPORT_UNUSED_SYMBOL_GPL(sym) diff --git a/kernel/module.c b/kernel/module.c index ff2d7359a418..26c13173da3d 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1400,7 +1400,7 @@ static int verify_namespace_is_imported(const struct load_info *info, char *imported_namespace; namespace = kernel_symbol_namespace(sym); - if (namespace) { + if (namespace && namespace[0]) { imported_namespace = get_modinfo(info, "import_ns"); while (imported_namespace) { if (strcmp(namespace, imported_namespace) == 0)