From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C78A2C433EF for ; Mon, 20 Dec 2021 14:01:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233319AbhLTOB4 (ORCPT ); Mon, 20 Dec 2021 09:01:56 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:49186 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233300AbhLTOBz (ORCPT ); Mon, 20 Dec 2021 09:01:55 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B850C6115C for ; Mon, 20 Dec 2021 14:01:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFACBC36AED; Mon, 20 Dec 2021 14:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1640008914; bh=kvnFKOvaR5qhoO+h5aA/rjGoloa3TsguK9JnuCFJCC0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DOJ9diqyEGAFgjaUpAHDmOVJHnc6gPhQ2BfhZAbVAJmqycm5CWRvbzq+Tk9i80X+5 iA4aqJ1KxO8a4Kfxdd7rVUqfBTT9iz7L01uRxqaJrkYbzRRwMXmBLYPMeqIqPhjpZN kOFq4PgijAqW7lGxHuXIGQCCF8qSrxM+CYcujiIu3yRid5RwONMAxZldbdnTd7Q364 ue9ifNbf3NRKnflZNaX4hoK6lyumipvyDyesAW9mraWJjiWHSVNdkXag/dahPIpbJ4 j+SOIeY/gnCZ/CHbiB6ABdvJbXYxlXtH6unUtlzZ8VGRj9nXqfQIbwihW/VWeLZuRY 6dxKeoKdb5avg== From: Frederic Weisbecker To: LKML Cc: Ard Biesheuvel , Steven Rostedt , Peter Zijlstra , Kees Cook , James Morse , David Laight , Sami Tolvanen , Frederic Weisbecker , Josh Poimboeuf , Andy Lutomirski , Quentin Perret , Catalin Marinas , Will Deacon , Mark Rutland Subject: [PATCH 1/5] static_call: Use non-function types to refer to the trampolines Date: Mon, 20 Dec 2021 15:01:38 +0100 Message-Id: <20211220140142.922323-2-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211220140142.922323-1-frederic@kernel.org> References: <20211220140142.922323-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel In order to prevent CFI enabled code from grabbing a jump table entry that jumps to the trampoline, rather than the trampoline itself, use an incomplete non-function type for the trampoline, and cast it to the right type only when invoking it. Acked-by: Peter Zijlstra (Intel) Signed-off-by: Ard Biesheuvel Cc: Mark Rutland Cc: Quentin Perret Cc: Catalin Marinas Cc: James Morse Cc: Will Deacon Cc: Kees Cook Cc: Sami Tolvanen Cc: Andy Lutomirski Cc: Josh Poimboeuf Cc: Steven Rostedt Signed-off-by: Frederic Weisbecker --- include/linux/static_call.h | 4 ++-- include/linux/static_call_types.h | 11 ++++++++--- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/include/linux/static_call.h b/include/linux/static_call.h index 3e56a9751c06..616607393273 100644 --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -151,7 +151,7 @@ extern void arch_static_call_transform(void *site, void *tramp, void *func, bool #define static_call_update(name, func) \ ({ \ - typeof(&STATIC_CALL_TRAMP(name)) __F = (func); \ + typeof(&STATIC_CALL_TYPE(name)) __F = (func); \ __static_call_update(&STATIC_CALL_KEY(name), \ STATIC_CALL_TRAMP_ADDR(name), __F); \ }) @@ -306,7 +306,7 @@ static inline void __static_call_nop(void) { } void *func = READ_ONCE(STATIC_CALL_KEY(name).func); \ if (!func) \ func = &__static_call_nop; \ - (typeof(STATIC_CALL_TRAMP(name))*)func; \ + (typeof(&STATIC_CALL_TYPE(name)))func; \ }) #define static_call_cond(name) (void)__static_call_cond(name) diff --git a/include/linux/static_call_types.h b/include/linux/static_call_types.h index 5a00b8b2cf9f..5e658ef537e4 100644 --- a/include/linux/static_call_types.h +++ b/include/linux/static_call_types.h @@ -18,6 +18,9 @@ #define STATIC_CALL_TRAMP(name) __PASTE(STATIC_CALL_TRAMP_PREFIX, name) #define STATIC_CALL_TRAMP_STR(name) __stringify(STATIC_CALL_TRAMP(name)) +#define STATIC_CALL_TYPE_PREFIX __SCtype__ +#define STATIC_CALL_TYPE(name) __PASTE(STATIC_CALL_TYPE_PREFIX, name) + /* * Flags in the low bits of static_call_site::key. */ @@ -36,11 +39,13 @@ struct static_call_site { #define DECLARE_STATIC_CALL(name, func) \ extern struct static_call_key STATIC_CALL_KEY(name); \ - extern typeof(func) STATIC_CALL_TRAMP(name); + extern struct static_call_tramp STATIC_CALL_TRAMP(name); \ + extern typeof(func) STATIC_CALL_TYPE(name) #ifdef CONFIG_HAVE_STATIC_CALL -#define __raw_static_call(name) (&STATIC_CALL_TRAMP(name)) +#define __raw_static_call(name) \ + ((typeof(&STATIC_CALL_TYPE(name)))&STATIC_CALL_TRAMP(name)) #ifdef CONFIG_HAVE_STATIC_CALL_INLINE @@ -96,7 +101,7 @@ struct static_call_key { }; #define static_call(name) \ - ((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func)) + ((typeof(&STATIC_CALL_TYPE(name)))(STATIC_CALL_KEY(name).func)) #endif /* CONFIG_HAVE_STATIC_CALL */ -- 2.25.1