From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CA99C9446 for ; Sun, 13 Aug 2023 21:35:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F253C433C8; Sun, 13 Aug 2023 21:35:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691962532; bh=XjgvC2k3FC8AtJi18NyLW0cqKXTOhvGuPdfygv/2zk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IMhjVb7Mb2jzefJ3ylnyxaACuwZUt7k7IqENHE6Iq+iXuh4YD2eOjKASFZIDpUp15 q7vZdhhIDgD+HwqlT8tvtSPl5UEh1YOn83p3VJg+tjRocURjcK710zk7KpMC9LwARY cZpaCN5xaAaKo4sbNom4ZHSh6N2+WtFHkrnSg/Ps= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nathan Chancellor , Daniel Kolesa , Naresh Kamboju , Sven Volkinsfeld , Nick Desaulniers , "Borislav Petkov (AMD)" Subject: [PATCH 6.1 064/149] x86/srso: Fix build breakage with the LLVM linker Date: Sun, 13 Aug 2023 23:18:29 +0200 Message-ID: <20230813211720.720506977@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230813211718.757428827@linuxfoundation.org> References: <20230813211718.757428827@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Nick Desaulniers commit cbe8ded48b939b9d55d2c5589ab56caa7b530709 upstream. The assertion added to verify the difference in bits set of the addresses of srso_untrain_ret_alias() and srso_safe_ret_alias() would fail to link in LLVM's ld.lld linker with the following error: ld.lld: error: ./arch/x86/kernel/vmlinux.lds:210: at least one side of the expression must be absolute ld.lld: error: ./arch/x86/kernel/vmlinux.lds:211: at least one side of the expression must be absolute Use ABSOLUTE to evaluate the expression referring to at least one of the symbols so that LLD can evaluate the linker script. Also, add linker version info to the comment about XOR being unsupported in either ld.bfd or ld.lld until somewhat recently. Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Closes: https://lore.kernel.org/llvm/CA+G9fYsdUeNu-gwbs0+T6XHi4hYYk=Y9725-wFhZ7gJMspLDRA@mail.gmail.com/ Reported-by: Nathan Chancellor Reported-by: Daniel Kolesa Reported-by: Naresh Kamboju Suggested-by: Sven Volkinsfeld Signed-off-by: Nick Desaulniers Signed-off-by: Borislav Petkov (AMD) Link: https://github.com/ClangBuiltLinux/linux/issues/1907 Link: https://lore.kernel.org/r/20230809-gds-v1-1-eaac90b0cbcc@google.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/vmlinux.lds.S | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -514,11 +514,17 @@ INIT_PER_CPU(irq_stack_backing_store); #ifdef CONFIG_CPU_SRSO /* - * GNU ld cannot do XOR so do: (A | B) - (A & B) in order to compute the XOR + * GNU ld cannot do XOR until 2.41. + * https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=f6f78318fca803c4907fb8d7f6ded8295f1947b1 + * + * LLVM lld cannot do XOR until lld-17. + * https://github.com/llvm/llvm-project/commit/fae96104d4378166cbe5c875ef8ed808a356f3fb + * + * Instead do: (A | B) - (A & B) in order to compute the XOR * of the two function addresses: */ -. = ASSERT(((srso_untrain_ret_alias | srso_safe_ret_alias) - - (srso_untrain_ret_alias & srso_safe_ret_alias)) == ((1 << 2) | (1 << 8) | (1 << 14) | (1 << 20)), +. = ASSERT(((ABSOLUTE(srso_untrain_ret_alias) | srso_safe_ret_alias) - + (ABSOLUTE(srso_untrain_ret_alias) & srso_safe_ret_alias)) == ((1 << 2) | (1 << 8) | (1 << 14) | (1 << 20)), "SRSO function pair won't alias"); #endif