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 419E0C38A04 for ; Thu, 10 Mar 2022 14:33:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244348AbiCJOdT (ORCPT ); Thu, 10 Mar 2022 09:33:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244926AbiCJO3k (ORCPT ); Thu, 10 Mar 2022 09:29:40 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCADE156792; Thu, 10 Mar 2022 06:25:03 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 41C7CB82544; Thu, 10 Mar 2022 14:25:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE7F2C340E8; Thu, 10 Mar 2022 14:25:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646922302; bh=Zy7ESnXJ/lsVEyziSCsKdmIWNOqS6ARmQC6cp9E55Qw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rtPOTfwVeikkehEntsuVAGwtDBLfGCeyw30rIvGpvdwDgDrF/9mX2/WDo3z5n/eWj TKI2sV6uQM853KC+6ygEtvO0ZjSd5ce9Z6oNX9XrhFxTCQi3CSExmIE1x73aBgPsRK T9X+gIR1rcieX0PZdZGhWU09wzPKKA09gChzEti0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Catalin Marinas , James Morse Subject: [PATCH 5.10 34/58] arm64: entry: Add vectors that have the bhb mitigation sequences Date: Thu, 10 Mar 2022 15:18:54 +0100 Message-Id: <20220310140813.845491188@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220310140812.869208747@linuxfoundation.org> References: <20220310140812.869208747@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: James Morse commit ba2689234be92024e5635d30fe744f4853ad97db upstream. Some CPUs affected by Spectre-BHB need a sequence of branches, or a firmware call to be run before any indirect branch. This needs to go in the vectors. No CPU needs both. While this can be patched in, it would run on all CPUs as there is a single set of vectors. If only one part of a big/little combination is affected, the unaffected CPUs have to run the mitigation too. Create extra vectors that include the sequence. Subsequent patches will allow affected CPUs to select this set of vectors. Later patches will modify the loop count to match what the CPU requires. Reviewed-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/assembler.h | 24 ++++++++++++++++ arch/arm64/include/asm/vectors.h | 34 +++++++++++++++++++++++ arch/arm64/kernel/entry.S | 53 ++++++++++++++++++++++++++++++------- include/linux/arm-smccc.h | 5 +++ 4 files changed, 107 insertions(+), 9 deletions(-) create mode 100644 arch/arm64/include/asm/vectors.h --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -795,4 +795,28 @@ USER(\label, ic ivau, \tmp2) // invali #endif /* GNU_PROPERTY_AARCH64_FEATURE_1_DEFAULT */ + .macro __mitigate_spectre_bhb_loop tmp +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY + mov \tmp, #32 +.Lspectre_bhb_loop\@: + b . + 4 + subs \tmp, \tmp, #1 + b.ne .Lspectre_bhb_loop\@ + sb +#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ + .endm + + /* Save/restores x0-x3 to the stack */ + .macro __mitigate_spectre_bhb_fw +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY + stp x0, x1, [sp, #-16]! + stp x2, x3, [sp, #-16]! + mov w0, #ARM_SMCCC_ARCH_WORKAROUND_3 +alternative_cb smccc_patch_fw_mitigation_conduit + nop // Patched to SMC/HVC #0 +alternative_cb_end + ldp x2, x3, [sp], #16 + ldp x0, x1, [sp], #16 +#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ + .endm #endif /* __ASM_ASSEMBLER_H */ --- /dev/null +++ b/arch/arm64/include/asm/vectors.h @@ -0,0 +1,34 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2022 ARM Ltd. + */ +#ifndef __ASM_VECTORS_H +#define __ASM_VECTORS_H + +/* + * Note: the order of this enum corresponds to two arrays in entry.S: + * tramp_vecs and __bp_harden_el1_vectors. By default the canonical + * 'full fat' vectors are used directly. + */ +enum arm64_bp_harden_el1_vectors { +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY + /* + * Perform the BHB loop mitigation, before branching to the canonical + * vectors. + */ + EL1_VECTOR_BHB_LOOP, + + /* + * Make the SMC call for firmware mitigation, before branching to the + * canonical vectors. + */ + EL1_VECTOR_BHB_FW, +#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ + + /* + * Remap the kernel before branching to the canonical vectors. + */ + EL1_VECTOR_KPTI, ++}; + +#endif /* __ASM_VECTORS_H */ --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -816,13 +816,26 @@ alternative_else_nop_endif sub \dst, \dst, PAGE_SIZE .endm - .macro tramp_ventry, vector_start, regsize, kpti + +#define BHB_MITIGATION_NONE 0 +#define BHB_MITIGATION_LOOP 1 +#define BHB_MITIGATION_FW 2 + + .macro tramp_ventry, vector_start, regsize, kpti, bhb .align 7 1: .if \regsize == 64 msr tpidrro_el0, x30 // Restored in kernel_ventry .endif + .if \bhb == BHB_MITIGATION_LOOP + /* + * This sequence must appear before the first indirect branch. i.e. the + * ret out of tramp_ventry. It appears here because x30 is free. + */ + __mitigate_spectre_bhb_loop x30 + .endif // \bhb == BHB_MITIGATION_LOOP + .if \kpti == 1 /* * Defend against branch aliasing attacks by pushing a dummy @@ -850,6 +863,15 @@ alternative_else_nop_endif ldr x30, =vectors .endif // \kpti == 1 + .if \bhb == BHB_MITIGATION_FW + /* + * The firmware sequence must appear before the first indirect branch. + * i.e. the ret out of tramp_ventry. But it also needs the stack to be + * mapped to save/restore the registers the SMC clobbers. + */ + __mitigate_spectre_bhb_fw + .endif // \bhb == BHB_MITIGATION_FW + add x30, x30, #(1b - \vector_start + 4) ret .org 1b + 128 // Did we overflow the ventry slot? @@ -857,6 +879,9 @@ alternative_else_nop_endif .macro tramp_exit, regsize = 64 adr x30, tramp_vectors +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY + add x30, x30, SZ_4K +#endif msr vbar_el1, x30 ldr lr, [sp, #S_LR] tramp_unmap_kernel x29 @@ -868,26 +893,32 @@ alternative_else_nop_endif sb .endm - .macro generate_tramp_vector, kpti + .macro generate_tramp_vector, kpti, bhb .Lvector_start\@: .space 0x400 .rept 4 - tramp_ventry .Lvector_start\@, 64, \kpti + tramp_ventry .Lvector_start\@, 64, \kpti, \bhb .endr .rept 4 - tramp_ventry .Lvector_start\@, 32, \kpti + tramp_ventry .Lvector_start\@, 32, \kpti, \bhb .endr .endm #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 /* * Exception vectors trampoline. + * The order must match __bp_harden_el1_vectors and the + * arm64_bp_harden_el1_vectors enum. */ .pushsection ".entry.tramp.text", "ax" .align 11 SYM_CODE_START_NOALIGN(tramp_vectors) - generate_tramp_vector kpti=1 +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY + generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP + generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW +#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ + generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE SYM_CODE_END(tramp_vectors) SYM_CODE_START(tramp_exit_native) @@ -914,7 +945,7 @@ SYM_DATA_END(__entry_tramp_data_start) * Exception vectors for spectre mitigations on entry from EL1 when * kpti is not in use. */ - .macro generate_el1_vector + .macro generate_el1_vector, bhb .Lvector_start\@: kernel_ventry 1, sync_invalid // Synchronous EL1t kernel_ventry 1, irq_invalid // IRQ EL1t @@ -927,17 +958,21 @@ SYM_DATA_END(__entry_tramp_data_start) kernel_ventry 1, error // Error EL1h .rept 4 - tramp_ventry .Lvector_start\@, 64, kpti=0 + tramp_ventry .Lvector_start\@, 64, 0, \bhb .endr .rept 4 - tramp_ventry .Lvector_start\@, 32, kpti=0 + tramp_ventry .Lvector_start\@, 32, 0, \bhb .endr .endm +/* The order must match tramp_vecs and the arm64_bp_harden_el1_vectors enum. */ .pushsection ".entry.text", "ax" .align 11 SYM_CODE_START(__bp_harden_el1_vectors) - generate_el1_vector +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY + generate_el1_vector bhb=BHB_MITIGATION_LOOP + generate_el1_vector bhb=BHB_MITIGATION_FW +#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ SYM_CODE_END(__bp_harden_el1_vectors) .popsection --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -87,6 +87,11 @@ ARM_SMCCC_SMC_32, \ 0, 0x7fff) +#define ARM_SMCCC_ARCH_WORKAROUND_3 \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + 0, 0x3fff) + #define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED 1 /* Paravirtualised time calls (defined by ARM DEN0057A) */