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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=9TLfWaf58UYL7wICLMCVVnhaOCpYf+H5DpQSRdiy6Cc=; b=tk1kUxaELgrrlKxUh7xS/4vWiJhqUh6BVOthIjHDtOcBwa2irrPcJeSUv4IDeqAus4 YAgT9pg4rfFdmo6P+z7SW8JNLCXGUVUagMllSm49qWPTP4ekD/Jq8PMcLF+ukmFfS0Pv Tina8HkRiRXec23jSuxeowl6j7XdSXXjVKOVUtY/ZXQ/whnT0DQ1jB75lYRtR3vnuHYK LFkvlphcQO8Wjn+lJGlP7YxQzHsN7OflOfyVSsOiJ/Gt0RpnUAhU5FKeSpSMmXOs0rrO hOtWiEWXLE+k0qjbzTEMWrHKWf31MwM2AYm22nOm58a+Y10FS31OMKVicAd9a/iA7Mvo SY3A== X-Gm-Message-State: AOAM532jz2fj1HJnj2gC11+h9PCH4UF16Hi2vFEhWYucmA8CMTzB/1W8 aZx6HDhf3HpHlOJj3LADzJaqRRsPVavVa5CWhS4= X-Google-Smtp-Source: ABdhPJxOTg1pZ6kKhg4/TLTiKW5mUxnxwTfGU0xF4tIiotwCBx+K30YxUBmIUhBVi6sN8mztOiZkcgmhCe/rnpjaMvs= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:f693:9fff:fef4:1b6d]) (user=samitolvanen job=sendgmr) by 2002:a05:6214:302:: with SMTP id i2mr1391507qvu.14.1607712411329; Fri, 11 Dec 2020 10:46:51 -0800 (PST) Date: Fri, 11 Dec 2020 10:46:25 -0800 In-Reply-To: <20201211184633.3213045-1-samitolvanen@google.com> Message-Id: <20201211184633.3213045-9-samitolvanen@google.com> Mime-Version: 1.0 References: <20201211184633.3213045-1-samitolvanen@google.com> X-Mailer: git-send-email 2.29.2.576.ga3fc446d84-goog Subject: [PATCH v9 08/16] init: lto: fix PREL32 relocations From: Sami Tolvanen To: Masahiro Yamada , Steven Rostedt , Will Deacon X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201211_134654_937557_1615CD5E X-CRM114-Status: GOOD ( 13.83 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Kees Cook , "Paul E. McKenney" , kernel-hardening@lists.openwall.com, Peter Zijlstra , Greg Kroah-Hartman , linux-kbuild@vger.kernel.org, Nick Desaulniers , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, clang-built-linux@googlegroups.com, Sami Tolvanen , Josh Poimboeuf , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org With LTO, the compiler can rename static functions to avoid global naming collisions. As initcall functions are typically static, renaming can break references to them in inline assembly. This change adds a global stub with a stable name for each initcall to fix the issue when PREL32 relocations are used. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- include/linux/init.h | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/include/linux/init.h b/include/linux/init.h index d466bea7ecba..27b9478dcdef 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -209,26 +209,49 @@ extern bool initcall_debug; */ #define __initcall_section(__sec, __iid) \ #__sec ".init.." #__iid + +/* + * With LTO, the compiler can rename static functions to avoid + * global naming collisions. We use a global stub function for + * initcalls to create a stable symbol name whose address can be + * taken in inline assembly when PREL32 relocations are used. + */ +#define __initcall_stub(fn, __iid, id) \ + __initcall_name(initstub, __iid, id) + +#define __define_initcall_stub(__stub, fn) \ + int __init __stub(void); \ + int __init __stub(void) \ + { \ + return fn(); \ + } \ + __ADDRESSABLE(__stub) #else #define __initcall_section(__sec, __iid) \ #__sec ".init" + +#define __initcall_stub(fn, __iid, id) fn + +#define __define_initcall_stub(__stub, fn) \ + __ADDRESSABLE(fn) #endif #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS -#define ____define_initcall(fn, __name, __sec) \ - __ADDRESSABLE(fn) \ +#define ____define_initcall(fn, __stub, __name, __sec) \ + __define_initcall_stub(__stub, fn) \ asm(".section \"" __sec "\", \"a\" \n" \ __stringify(__name) ": \n" \ - ".long " #fn " - . \n" \ + ".long " __stringify(__stub) " - . \n" \ ".previous \n"); #else -#define ____define_initcall(fn, __name, __sec) \ +#define ____define_initcall(fn, __unused, __name, __sec) \ static initcall_t __name __used \ __attribute__((__section__(__sec))) = fn; #endif #define __unique_initcall(fn, id, __sec, __iid) \ ____define_initcall(fn, \ + __initcall_stub(fn, __iid, id), \ __initcall_name(initcall, __iid, id), \ __initcall_section(__sec, __iid))