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 221FEC433EF for ; Fri, 18 Mar 2022 12:12:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236052AbiCRMNZ (ORCPT ); Fri, 18 Mar 2022 08:13:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229499AbiCRMNX (ORCPT ); Fri, 18 Mar 2022 08:13:23 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 170521FAA18; Fri, 18 Mar 2022 05:12:05 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C34171424; Fri, 18 Mar 2022 05:12:04 -0700 (PDT) Received: from [10.57.88.118] (unknown [10.57.88.118]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B1CC63F7F5; Fri, 18 Mar 2022 05:12:03 -0700 (PDT) Subject: Re: [PATCH 5.4 18/43] arm64: entry: Add macro for reading symbol addresses from the trampoline To: Florian Fainelli , Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Catalin Marinas , Sasha Levin References: <20220317124527.672236844@linuxfoundation.org> <20220317124528.180267687@linuxfoundation.org> <113e7675-4263-2a20-81d0-9634f03511d2@gmail.com> From: James Morse Message-ID: Date: Fri, 18 Mar 2022 12:11:32 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <113e7675-4263-2a20-81d0-9634f03511d2@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Florian, On 3/17/22 8:48 PM, Florian Fainelli wrote: > On 3/17/22 5:45 AM, Greg Kroah-Hartman wrote: >> From: James Morse >> >> commit b28a8eebe81c186fdb1a0078263b30576c8e1f42 upstream. >> >> The trampoline code needs to use the address of symbols in the wider >> kernel, e.g. vectors. PC-relative addressing wouldn't work as the >> trampoline code doesn't run at the address the linker expected. >> >> tramp_ventry uses a literal pool, unless CONFIG_RANDOMIZE_BASE is >> set, in which case it uses the data page as a literal pool because >> the data page can be unmapped when running in user-space, which is >> required for CPUs vulnerable to meltdown. >> >> Pull this logic out as a macro, instead of adding a third copy >> of it. >> >> Reviewed-by: Catalin Marinas >> Signed-off-by: James Morse >> Signed-off-by: Sasha Levin > > This commit causes a linking failure with CONFIG_ARM_SDE_INTERFACE=y > enabled in the kernel: > > LD .tmp_vmlinux.kallsyms1 > /local/users/fainelli/buildroot/output/arm64/host/bin/aarch64-linux-ld: > arch/arm64/kernel/entry.o: in function `__sdei_asm_exit_trampoline': > /local/users/fainelli/buildroot/output/arm64/build/linux-custom/arch/arm64/kernel/entry.S:1352: > undefined reference to `__sdei_asm_trampoline_next_handler' > make[2]: *** [Makefile:1100: vmlinux] Error 1 > make[1]: *** [package/pkg-generic.mk:295: > /local/users/fainelli/buildroot/output/arm64/build/linux-custom/.stamp_built] > Error 2 > make: *** [Makefile:27: _all] Error 2 ... and with CONFIG_RANDOMIZE_BASE turned off, which is why allyesconfig didn't catch it. This is because I kept the next_handler bit of the label when it conflicted, which isn't needed because the __entry_tramp bit added by the macro serves the same purpose. The below diff fixes it: ----------%<---------- diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index e4b5a15c2e2e..cfc0bb6c49f7 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -1190,7 +1190,7 @@ __entry_tramp_data_start: __entry_tramp_data_vectors: .quad vectors #ifdef CONFIG_ARM_SDE_INTERFACE -__entry_tramp_data___sdei_asm_trampoline_next_handler: +__entry_tramp_data___sdei_asm_handler: .quad __sdei_asm_handler #endif /* CONFIG_ARM_SDE_INTERFACE */ .popsection // .rodata @@ -1319,7 +1319,7 @@ ENTRY(__sdei_asm_entry_trampoline) */ 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] - tramp_data_read_var x4, __sdei_asm_trampoline_next_handler + tramp_data_read_var x4, __sdei_asm_handler br x4 ENDPROC(__sdei_asm_entry_trampoline) NOKPROBE(__sdei_asm_entry_trampoline) ----------%<---------- Good news - this didn't happen with v5.10. I don't see this in v5.4.185 yet. Greg/Sasha, what is least work for you?: A new version of this patch, A fixup on top of the series, Reposting the series with this fixed. Thanks for catching this! James